liu.seSök publikationer i DiVA
Ändra sökning
Avgränsa sökresultatet
1234567 1 - 50 av 587
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    A study on fatigue damage and crack initiation in austenitic steel matrix during very high cycle fatigue2024Ingår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 179, artikel-id 108033Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fatigue damage and crack initiation behavior has been studied in an austenitic stainless steel using a novel progressive stepwise load increasing method with a cycle step greater than 108 cycles and investigated with a FIB-SEM. Subsurface crack origin with a fine granular area in the matrix was formed. Heterogeneous plastic deformation causes strain localization and grain fragmentation. Localized plasticity exhaustion induces crack initiation. A crack origin is completed once a short crack reaches the stress intensity factor threshold for stage II crack propagation. This study provides a fundamental discussion how damage and crack initiation in matrix occur during very high cycle fatigue.

  • 2.
    Zhu, Zhenyu
    et al.
    Chengdu Univ, Peoples R China.
    Chen, Maolin
    Chengdu Univ, Peoples R China.
    He, Mingge
    CNPC Chuanqing Drilling Engn Co Ltd, Peoples R China.
    Zhang, Junliang
    PetroChina, Peoples R China.
    Huang, Yanyan
    Chengdu Univ, Peoples R China.
    Chen, Siqi
    PetroChina, Peoples R China.
    Du, Xuanyu
    PetroChina, Peoples R China.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Chengdu Univ, Peoples R China.
    Wang, Qingyuan
    Chengdu Univ, Peoples R China.
    Coupling life prediction of bending very high cycle fatigue of completion strings made of different materials using deep wise separable convolution2024Ingår i: Fatigue & Fracture of Engineering Materials & Structures, ISSN 8756-758X, E-ISSN 1460-2695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article predicts bending very high cycle fatigue (VHCF) life of three typical nickel-based alloys SM2550, BG2532, and G3 used for completion strings. Fatigue tests were conducted on the three alloys using an ultrasonic fatigue system at a frequency of 20 kHz. The results showed that the fatigue strength ranges of the three alloys were markedly different, reflecting their different sensitivities to fatigue loading. Scanning electron microscope observations revealed numerous fatigue crack origins with internal decohesion in the fatigue source region. To achieve unified prediction of the fatigue life for the three alloys, a prediction model based on deep learning was built with inputs including fatigue initiation quantity, cleavage facet size, and other fatigue fracture characteristics. It was found that single source feature was insufficient to obtain satisfactory prediction accuracy for all alloys, while multifeature coupling integration could significantly improve the prediction precision, enabling reliable prediction of alloy fatigue life. This study provides new insights into bending VHCF life prediction. This article predicts bending VHCF life for three completion strings. Bending VHCF life model utilizing deep wise separable convolution was established. Deep learning can effectively integrate with bending VHCF analyses.

  • 3.
    Chalapathi, Darshan
    et al.
    Laboratory for Mechanics of Microstructures, Department of Metallurgical and Materials Engineering, IIT Madras, Chennai, India.
    Nordström, Joakim
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima, Sandviken, Sweden.
    Siriki, Raveendra
    Alleima, Sandviken, Sweden.
    Lautrup, Lisa
    Alleima, Sandviken, Sweden.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima, Sandviken, Sweden.
    Kanjarla, Anand K.
    Laboratory for Mechanics of Microstructures, Department of Metallurgical and Materials Engineering, IIT Madras, Chennai, India.
    Deformation twinning and the role of stacking fault energy during cryogenic testing of Ni-based superalloy 6252024Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 898, artikel-id 146404Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ni-based superalloys play a crucial role in various high-temperature applications, where their exceptional mechanical properties and resistance to corrosion are highly desirable. However, their response to low temperatures, especially concerning strain hardening, microstructural evolution, and deformation mechanisms, requires further scrutiny. In this study, we investigate the influence of temperature on the stacking fault energy (SFE) and its implications on deformation twinning in Alloy 625. Uniaxial tensile tests are performed at 298 K, 173 K and 77 K. The study reveals a notable increase in strain hardening at intermediate strain levels, suggesting the activation of a secondary deformation mechanism. To gain deeper insights, crystal plasticity-based simulations using the DAMASK framework are employed, complementing the experimental outcomes. Deformation twins are consistently observed at all temperatures, albeit with a small volume fraction and thickness. The critical strain for twinning decreased with decreasing temperature. Based on the numerous literature studies, experimental and computational observations, the SFE of the material is estimated to be constant over the studied temperature range.

  • 4.
    Nordström, Joakim
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Deformation twinning in corrosion-resistant nickel alloys: with a rising nickel content2024Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Sanicro 28 och Alloy 625 är två legeringar med ett imponerande korrosionsmotstånd, ett lågt kolinnehåll och en helaustenitisk struktur. Det gör dem väl lämpade för kallbearbetning. Sedan millenieskiftet har aktivten varit mycket hög inom forskningsområdet: deformationstvillingar. TWIP (twinning induced plasticity)-effekten har den så eftertraktade egenskapen att både styrkan och duktiliteten förbättras på samma gång. Eftersom nickel har en hög staplingsfelsenergi och TWIP-effekten har uppmätts/beräknats till att aktiveras vid ett snävt och lågt värde, för densamma, har ett ökande nickelinnehåll och TWIP-effekten setts som direkta motpoler. Trots det, har man länge vetat om att deformationstvillingar också framträder, om än, vid låga temperaturer, i legeringar med kubiskt ytcentrerat gitter och hög staplingsfelsenergi.

    I den här avhandlingen har vi undersökt hur deformationstvillingar utvecklas, om de ens kan bildas i korrosionsbeständiga legeringar med ett högt nickelinnehåll. Målet är att se om det finns några större skillnader i tvillingbeteendet i TWIP-stål i jämförelse med korrosionsbeständiga legeringar med ett högt nickelinnehåll. Några egenskaper vi har tänkt att undersöka är: tjocklek på tvillingarna och om tvillingarna bildas i grupper. Vi hoppas på så sätt kunna svara på den övergripande forskningsfrågan: är det möjligt att designa ett rostfritt TWIP-stål, baserat på det vanligaste legeringssystemet för rostfria austenitiska stål, nämligen: järn-krom-nickel?

    Enaxliga dragprov har genomförts vid flera kallbearbetningstemperatuer; de har utförts både till brott och till förutbestämda töjningsnivåer. Legeringarna som har testats är: Sanicro 28 (31% nickel) och Alloy 625 (61% nickel). Mikrostrukturen har framför allt karakteriserats i material uttaget från volym där deformationen har varit homogen. De analysmetoder som har använts är: svepelektronmikroskopi, mer specifikt: ”electron backscatter diffraction” och ”electron channelling contrast imaging”. Transmissionselektronmikroskop och röntgendiffraktion har också använts. I en undersökning har också brottbeteende studerats med hjälp av "secondary electrons".

    Ab initioberäkningar, modellering av kristallplasticitet och materialbeteende med hjälp av DAMASK har också utförts för att kunna se vilka deformationsmekanismer som är aktiva.

    Vi upptäckte att deformationstvillingar faktiskt kan bildas i korrosionsbeständiga legeringar med ett högt nickelinnehåll. Den diffusa midjebildningen minskar på samma gång som andelelen deformationstvillingar ökar.

    Ab initioberäkningarnas resultat indikerar också på att deformationstvillingarnas inträde inte enbart kan bestämmas med staplingsfelsenergin.

    Tydliga mikrostrukturmönster upptäcktes med hjälp av transmissionsmiroskop och vid låga töjningsnivåer. De mikrostrukturmönstren kunde avfärdas från att vara både deformationstvillingar och staplingsfel. Texturnivån ökar med ökande töjningsnivå och sjunkande temperatur. Typen av textur förändras också med sjunkande temperatur.

    Delarbeten
    1. Deformation Twinning Behavior in High Ni-Austenitic Materials
    Öppna denna publikation i ny flik eller fönster >>Deformation Twinning Behavior in High Ni-Austenitic Materials
    2018 (Engelska)Ingår i: THERMEC 2018: 10TH INTERNATIONAL CONFERENCE ON PROCESSING AND MANUFACTURING OF ADVANCED MATERIALS, TRANS TECH PUBLICATIONS LTD , 2018, Vol. 941, s. 1591-1596Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Deformation twinning behaviors have been studied in high Ni alloys, Alloy 28 or Sanicro 28 and Alloy 625 at RT and at cryogenic temperature. The microstructures were evaluated using SEM-EBSD. Some constitutive approach has also been used in the discussion on the deformation twinning in high Ni-alloys. The results show that deformation twinning can occur in high Ni alloys depending on the chemical composition, strain range and stress conditions. TWIP can occur in the Ni based superalloy Alloy 625 at cryogenic temperature, which increases both strength and ductility. This is the first report of this phenomena for this alloy. Deformation twinning in high Ni alloys occurs heterogeneously in the material, depending on crystallographic parameters such as grain orientation and Schmid factor. Formation of deformation twins can lead to high texture in the material, which will contribute to the increase of strength. The mechanisms for the formation of deformation twins in high Ni alloys have been discussed.

    Ort, förlag, år, upplaga, sidor
    TRANS TECH PUBLICATIONS LTD, 2018
    Serie
    Materials Science Forum, ISSN 0255-5476
    Nyckelord
    Nickel based superalloy; Ageing; Fracture toughness; Microstructure; Twinning
    Nationell ämneskategori
    Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-158400 (URN)10.4028/www.scientific.net/MSF.941.1591 (DOI)000468152500264 ()978-3-0357-1208-7 (ISBN)
    Konferens
    10th International Conference on Processing and Manufacturing of Advanced Materials Processing, Fabrication, Properties, Applications (THERMEC)
    Tillgänglig från: 2019-07-01 Skapad: 2019-07-01 Senast uppdaterad: 2024-05-17
    2. TWIP and Fracture Behaviour in the Superalloy 625 at Room and Cryogenic Temperatures
    Öppna denna publikation i ny flik eller fönster >>TWIP and Fracture Behaviour in the Superalloy 625 at Room and Cryogenic Temperatures
    Visa övriga...
    2019 (Engelska)Ingår i: Procedia Structural Integrity / [ed] Elsevier, Elsevier, 2019, Vol. 23, s. 457-462Konferensbidrag, Publicerat paper (Refereegranskat)
    Ort, förlag, år, upplaga, sidor
    Elsevier, 2019
    Nyckelord
    Deformation twinning, fracture, texture, Alloy 625, nickel base alloy, superalloy
    Nationell ämneskategori
    Materialteknik
    Identifikatorer
    urn:nbn:se:liu:diva-161738 (URN)10.1016/j.prostr.2020.01.129 (DOI)
    Konferens
    9th International Conference on Materials Structures and Micromechanics of Fracture, MSMF9, in Brno, Czech Republic, June 26-28, 2019
    Tillgänglig från: 2019-11-08 Skapad: 2019-11-08 Senast uppdaterad: 2024-05-17Bibliografiskt granskad
    3. Temperature study of deformation twinning behaviour in Nickel-base Superalloy 625
    Öppna denna publikation i ny flik eller fönster >>Temperature study of deformation twinning behaviour in Nickel-base Superalloy 625
    Visa övriga...
    2024 (Engelska)Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, artikel-id 146628Artikel i tidskrift (Refereegranskat) Epub ahead of print
    Abstract [en]

    Deformation behaviour in the Nickel-base superalloy 625 has been studied by tensile testing at four temperatures: 295, 223, 173 and 77 K. The microstructure has been investigated using TEM, FIB-SEM, EBSD and ECCI techniques. Deformation in the alloy turns out to be a competitive course of events between at least two deformation mechanisms, namely dislocation slip and deformation twinning. Slip is the predominant deformation mechanism at higher temperatures. While at 77 K, deformation induced twinning gives an extra degree of freedom as one of the main deformation mechanisms, i.e., the material shows a twin induced plasticity, TWIP, behaviour. Ab initio calculations indicate that the influence of cryogenic/sub-zero temperatures on the stacking fault energy of this alloy can be limited and that the formation of deformation twins cannot be determined solely by the stacking fault energy. The results implies that it is the critical strain and strain hardening rate that influences the deformation twinning onset and twinning rate.

    Nyckelord
    Ni-base alloy, Superalloy, Deformation induced twinning, Density function theory, Stacking fault energy
    Nationell ämneskategori
    Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-203601 (URN)10.1016/j.msea.2024.146628 (DOI)
    Tillgänglig från: 2024-05-20 Skapad: 2024-05-20 Senast uppdaterad: 2024-05-20Bibliografiskt granskad
    4. Deformation twinning and the role of stacking fault energy during cryogenic testing of Ni-based superalloy 625
    Öppna denna publikation i ny flik eller fönster >>Deformation twinning and the role of stacking fault energy during cryogenic testing of Ni-based superalloy 625
    Visa övriga...
    2024 (Engelska)Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 898, artikel-id 146404Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Ni-based superalloys play a crucial role in various high-temperature applications, where their exceptional mechanical properties and resistance to corrosion are highly desirable. However, their response to low temperatures, especially concerning strain hardening, microstructural evolution, and deformation mechanisms, requires further scrutiny. In this study, we investigate the influence of temperature on the stacking fault energy (SFE) and its implications on deformation twinning in Alloy 625. Uniaxial tensile tests are performed at 298 K, 173 K and 77 K. The study reveals a notable increase in strain hardening at intermediate strain levels, suggesting the activation of a secondary deformation mechanism. To gain deeper insights, crystal plasticity-based simulations using the DAMASK framework are employed, complementing the experimental outcomes. Deformation twins are consistently observed at all temperatures, albeit with a small volume fraction and thickness. The critical strain for twinning decreased with decreasing temperature. Based on the numerous literature studies, experimental and computational observations, the SFE of the material is estimated to be constant over the studied temperature range.

    Nyckelord
    Stacking fault energy, Deformation twinning, Cryogenic testing, Crystal plasticity
    Nationell ämneskategori
    Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-203479 (URN)10.1016/j.msea.2024.146404 (DOI)001219293800001 ()
    Tillgänglig från: 2024-05-15 Skapad: 2024-05-15 Senast uppdaterad: 2024-05-31Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner (png)
    presentationsbild
  • 5.
    Romanov, Pavel
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Jahedi, Arvid
    Univ Gavle, Sweden; Ericsson AB, Sweden.
    Backstrom, Anders
    Vaderstad Components AB, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Kubena, Ivo
    Inst Phys Mat ASCR, Czech Republic.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Differential Microstructure and Properties of Boron Steel Plates Obtained by Water Impinging Jet Quenching Technique2024Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 95, nr 1, artikel-id 2300406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil-working tools in agriculture are made of boron-containing steels with high wear resistance and hardenability. Nevertheless, these tools are subject to high impacts, abrasive wear, and fatigue and are therefore prone to failure. To combine varying levels of properties within one component in as-quenched condition can be beneficial for such products. To obtain this property variation, a component must undergo a complex and controllable cooling. Therefore, the aim of this work is to obtain a microstructure gradient along two 15 mm-thick steel plates in a newly developed test rig by water jet impingement technique to confirm its controllability and flexibility. Furthermore, a quenching simulation model is created for hardness prediction using phase transformation data from a machine learning tool. Microstructure variation is observed using light optical microscopy and the electron backscatter diffraction technique. Mechanical properties are studied through tensile tests and hardness measurements and are also compared with simulation results. The 0.27 mass% C steel sample is obtained in almost fully martensitic state transitioning to a softer ferritic/bainitic condition, while the 0.38 mass% C steel sample results predominantly into a fully hardened martensitic state and slightly shows ferritic and bainitic features along the sample. The quenching simulation model shows promising hardness prediction for both steels. A newly developed impinging jet quenching technique is used for differential quenching of 15 mm-thick boron steel sheets with the aim of obtaining microstructure and property gradients along their lengths. As a result, combinations of differential hardness profiles along with varying hardening degrees are produced and metallurgically characterized through microstructure observations and mechanical tests.

    Ladda ner fulltext (pdf)
    fulltext
  • 6.
    Sahbi Loukil, Mohamed
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Costa, Sergio
    RISE Res Inst Sweden AB, Sweden.
    Bergwall, Mats
    RISE Res Inst Sweden AB, Sweden.
    Prasad, H. S. Deepthi
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Moreau, Florence
    Oxeon AB, Sweden.
    Segersäll, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Kapidzic, Zlatan
    Saab AB, SE-58188 Linkoping, Sweden.
    Olsson, Robin
    RISE Res Inst Sweden AB, Sweden.
    Experimental and numerical investigation on bearing behavior of hybrid thin/thick-ply composite laminates2024Ingår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 331, artikel-id 117888Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Experimental and numerical studies were carried out to characterize hybrid thin- and thick-ply composite laminates and assess modelling capabilities. Five different composite laminates were manufactured using a single material system with varying proportions of thin plies (0%, 50%, and 100% thin-ply). Bearing tests were performed and the results from the tests were investigated. The results showed that performance, in terms of bearing strength at onset of damage and ultimate bearing stress, increased proportionally with the increasing amount of thin plies within the laminate. Microscopic examination of the failure modes for all laminates was performed at the center of the hole to determine the dominant failure mode. The numerical investigation uses a highly detailed mesoscale model previously validated for crash simulations but never used successfully to bearing damage areas. The results showed a good correlation regarding both the load response and the morphology of damage.

  • 7.
    Chai, Guocai
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    Lautrup, L.
    Alleima AB, Sweden.
    Gustavsson, F.
    Swerim AB, Sweden; Vattenfall, Sweden.
    Extra-long creep rupture life of Alleima 3R60™ (316/316L) stainless steel2024Ingår i: Materials at High Temperature, ISSN 0960-3409, E-ISSN 1878-6413, Vol. 41, nr 1, s. 169-176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alleima 3R60 (TM) is an AISI 316/316 L type of stainless steel. This alloy shows extra-long creep lives. At 700 degrees C with an applied stress of 45 MPa, the specimen broke first after 240 131 hours, a 140% longer creep life than the predicted. The reasons have been studied using SEM/EDS, EBSD, ECCI and TEM. Two unexpected phenomena have been observed. One is the presence of homogeneously dispersed small Mo2Fe4CrSi(Ni-0.5)f063type of precipitates in the matrix. According to the thermodynamic calculation, this phase should not form in this alloy at 700 degrees C. The other is the fine grains formed in the matrix during the creep-testing at 700 degrees C for such an extra-long time. It is believed that both small precipitates and fine grain size contribute to this extra-long creep life of the steel. With the microstructural study and thermodynamic simulation, the mechanisms to form precipitates and fine grains have been discussed.

  • 8.
    Wennersten, Karin
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Xu, Jinghao
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Armakavicius, Nerijus
    TekSiC AB, S-58330 Linkoping, Sweden.
    Wiberg, Anton
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Produktrealisering. Linköpings universitet, Tekniska fakulteten.
    Nadali Najafabadi, Hossein
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska fakulteten.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Feasibility of Melting NbC Using Electron Beam Powder Bed Fusion2024Ingår i: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High melting point materials such as ceramics and metal carbides are in general difficult to manufacture due to their physical properties, which imposes the need for new manufacturing methods where electron beam powder bed fusion (EB-PBF) seems promising. Most materials that have been successfully printed with EB-PBF are metals and metal alloys with good electrical conductivity, whereas dielectric materials such as ceramics are generally difficult to print. Catastrophic problems such as smoking and spattering can occur during the EB-PBF processing owing to inappropriate physical properties such as lack of electrical, and thermal conductivity and high melting point, which are challenging to overcome by process optimization. Due to these difficulties, a limited level of understanding has been achieved regarding melting ceramics and refractory alloys. Herein, three different substrates of niobium carbide (NbC) are melted using EB-PBF. The established process parameter window shows a good correlation between EB-PBF process parameters, surface, and melt characteristics, which can be used as a baseline for a printing process. Melting NbC is proven feasible using EB-PBF; the work also points out challenges related to arc trips and spattering, as well as future investigations necessary to create a stable printing process. Additive manufacturing offer new ways of manufacturing ceramics and metal carbides otherwise hard to produce. This study presents one of the first attempts at melting niobium carbide using electron beam powder bed fusion by identifying process window and investigating how the different process parameters affect the melt characteristics, as well as identifying potential issues regarding printing metal carbides.image (c) 2024 WILEY-VCH GmbH

  • 9.
    Fardan, Ahmed
    et al.
    Chalmers Univ Technol, Sweden.
    Fazi, Andrea
    Chalmers Univ Technol, Sweden.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Mishurova, Tatiana
    Bundesanstalt Mat Forsch & Prufung BAM, Germany.
    Thuvander, Mattias
    Chalmers Univ Technol, Sweden.
    Bruno, Giovanni
    Bundesanstalt Mat Forsch & Prufung BAM, Germany; Univ Potsdam, Germany.
    Brodin, Hakan
    Chalmers Univ Technol, Sweden; Siemens Energy AB, Sweden.
    Hryha, Eduard
    Chalmers Univ Technol, Sweden.
    Fine-Tuning Melt Pools and Microstructures: Taming Cracks in Powder Bed Fusion-Laser Beam of a non-weldable Ni-base Superalloy2024Ingår i: Materialia, E-ISSN 2589-1529, Vol. 34, artikel-id 102059Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Powder Bed Fusion - Laser Beam (PBF-LB) of high gamma' strengthened Ni-base superalloys, such as CM247LC, is of great interest for high temperature applications in gas turbines. However, PBF-LB of CM247LC is challenging due to the high cracking susceptibility during PBF-LB processing (solidification cracking) and heat treatment (strain age cracking, mostly caused by residual stresses). This study focuses on understanding the impact of process parameters on microstructure, residual stresses and solidification cracking. Laser power (P), speed (v) and hatch spacing (h) were varied while the layer thickness (t) was fixed. The melt pool size and shape were found to be key factors in minimizing solidification cracking. Narrower and shallower melt pools, achieved using a low line energy density (LED = P/v <= 0.1 J/mm), gave low crack densities (0.7 mm/mm2). A tight hatch spacing (h = 0.03 mm) resulted in reduced lack of fusion porosity. Electron backscatter diffraction investigations revealed that parameters giving finer microstructure with < 100 > crystallographic texture had low crack densities provided they were processed with a low LED. Atom probe tomography elucidated early stages of spinodal decomposition in the as-built condition, where Cr and Al cluster separately. The extent of spinodal decomposition was found to be affected by the LED and the hatch spacing. Samples with low LED and small hatch spacing showed higher degrees of spinodal decomposition. X-ray diffraction residual stress investigations revealed that the residual stress is proportional to the volumetric energy density (VED = P/(v. h. t)). Although low residual stresses can be achieved by using low VED, there is a high risk of lack of fusion. Hence, other parameters such as modified scan strategy, build plate pre-heating and pulsed laser mode, must be further explored to minimize the residual stresses to reduce the strain age cracking susceptibility.

  • 10.
    Schulz, Fiona
    et al.
    Chalmers Univ Technol, Sweden; Univ Bundeswehr Munchen, Germany.
    Lindgren, Kristina
    Chalmers Univ Technol, Sweden.
    Xu, Jinghao
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Hryha, Eduard
    Chalmers Univ Technol, Sweden.
    Gamma prime formation in nickel-based superalloy IN738LC manufactured by laser powder bed fusion2024Ingår i: Materials Today Communications, ISSN 2352-4928, Vol. 38, artikel-id 107905Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Complex components for high-temperature gas turbine applications require materials that offer a combination of excellent high-temperature strength and oxidation resistance. Nickel-based superalloys with high gamma prime (gamma)' volume fractions are particularly suited for these applications, especially combined with additive manufacturing for intricate geometries. Despite the complex thermal history that these materials experience during laser powder bed fusion (LPBF) processing, gamma'formation is suppressed when manufacturing IN738LC, which has a medium equilibrium gamma'content of about 40-50 vol%. This study follows gamma'formation in LPBF IN738LC during subsequent annealing treatments at temperatures ranging from 745 C-degrees to 865 C-degrees, creating an experimentally determined TTT (temperature-time-transformation) diagram. This diagram is largely based on scanning electron microscopy (SEM) imaging supported by Vickers hardness measurements and scanning transmission electron microscopy (STEM) bright field imaging. Atom probe tomography (APT) of the as-built material indicated nm-sized regions depleted in Cr and enriched in Ni, Al, and Ti, but show no characteristic superlattice patterns in TEM diffraction. APT and TEM diffraction analysis of material annealed at 850 C for 3 min confirmed the presence of the gamma'phase but indicated that gamma'had formed through spinodal decomposition instead of precipitation.

  • 11.
    Romanov, Pavel
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Jahedi, Arvid
    Ericsson AB, Sweden.
    Carlestam, Anders
    SSAB Special Steel, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Norman, Viktor
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Univ Gavle, Sweden.
    Hardening of Cylindrical Bars with Water Impinging Jet Quenching Technique2024Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hardening of carbon steel products by austenitization and immersion in a quenching medium is a widely used heat treatment to obtain a hard and strong martensitic structure. To avoid the undesired consequences, such as residual stresses or insufficient hardening depth, the cooling rates must be accurately measured and controlled. This can be achieved using the impinging water jet quenching technique. The aim of this work is to perform hardening of four low-alloyed 70 mm cylindrical carbon steel bars, using impinging water jet quenching technique with different jet flow rates, and to analyze its effect on thermal evolution and residual stresses. The temperature evolution during quenching experiments is recorded and used as input to a comprehensive quenching model to predict phase transformations, final hardness, and residual stresses of cylindrical bars. All four quenching experiments result in a fully hardened martensitic state. Furthermore, a decrease in jets' flow rate, within a certain interval, results in different thermal histories and in lower compressive residual stresses on the surface. The results from quenching simulations show promising hardness, microstructure, and residual stress predictions that are validated by hardness measurements, optical microscopy, and residual stress analysis using X-Ray diffraction method. Four 70 mm cylindrical steel bars are martensite hardened with different water jet flow rates using impinging jet quenching technique. A finite element method (FEM) quenching model is created to simulate phase transformations and predict the resulting microstructure, hardness, and residual stresses. The model is metallurgically validated through hardness measurements, microstructure observations, and residual stress measurements using X-ray diffraction technique.image (c) 2024 WILEY-VCH GmbH

  • 12.
    Ohlin, O.
    et al.
    Alleima, Sweden.
    Siriki, R.
    Alleima, Sweden.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Medicinska fakulteten. Linköpings universitet, Tekniska fakulteten. Alleima, Sweden.
    Long-term creep behaviours and structural stabilities of austenitic heat-resistant stainless steels2024Ingår i: Materials at High Temperature, ISSN 0960-3409, E-ISSN 1878-6413, Vol. 41, nr 1, s. 61-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For heat resistant alloys, long-term structural stability at high temperatures is a critical issue for alloy design and applications. In this paper, the long-term creep behaviours and structural stabilities of six heat resistant high Ni alloys and austenitic stainless steels have been studied. The longest creep rupture life is up to 359 283 hours. High Ni and Cr alloys show a good combination of high creep and oxidation resistances. Precipitation of nano MX particles with a very low growth rate improves long-term creep resistance at high temperatures. Long-term stable multiple nanoprecipitates of MX, Cu-rich, Laves and M23C6 phases can greatly contribute to the creep strength. Low Ni austenitic stainless steels show comparatively low oxidation and creep resistances. It was first found that at 800 & DEG;C, Cr2N could form in the low Ni steel with a long-term crept by the absorption of nitrogen from the air into the matrix.

  • 13.
    Schwerz, Claudia
    et al.
    Chalmers Univ Technol, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Sundar, Vishal
    Chalmers Univ Technol, Sweden.
    Bircher, Benjamin A.
    Fed Inst Metrol METAS, Switzerland.
    Kung, Alain
    Fed Inst Metrol METAS, Switzerland.
    Riabov, Dmitri
    Chalmers Univ Technol, Sweden; Hoganas AB, Sweden.
    Nyborg, Lars
    Chalmers Univ Technol, Sweden.
    Mechanical properties of Hastelloy X produced by laser powder bed fusion and affected by spatter redeposition2024Ingår i: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, ISSN 2238-7854, Vol. 29, s. 4200-4215Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Defects in materials manufactured via laser powder bed fusion challenge this manufacturing process' dependability and may prevent it from being comprehensively used for structural components, particularly those intended to operate under dynamic loading conditions. This study aims to investigate the effect of spatter-driven lack of fusion on the mechanical properties of Hastelloy X, with a particular focus on fatigue performance. Mechanical test specimens were manufactured in two builds with different build rates and monitored through insitu optical tomography. The images acquired in situ were analyzed to detect spatter redeposits to predict the defect content in the gauge section. Selected specimens were measured ex-situ using X-ray computed tomography to map the defect populations. Afterward, the specimens were tensile and fatigue tested, and their performance was analyzed based on the measured and expected defect populations. It was confirmed that a higher build rate is associated with more extensive detection of spatter redeposits in optical tomography images and lack of fusion defects. The fatigue lives of specimens manufactured at higher build rates presented higher scatter but significantly higher average, despite the more critical defect population. Surprisingly, the confirmed presence of lack of fusion defects in the gauge section of test specimens did not necessarily result in a poorer fatigue performance. It was concluded that the grain refinement obtained through the increase in nominal layer thickness has a lifeprolonging effect that overrides the effects of spatter-induced lack of fusion defects.

  • 14.
    Engel, B.
    et al.
    Univ Nottingham, England.
    Lavie, W. J.
    Univ Nottingham, England.
    Rouse, J. P.
    Univ Nottingham, England.
    Whittaker, M. T.
    Swansea Univ, Wales.
    Jones, J. P.
    Swansea Univ, Wales.
    Lancaster, R.
    Swansea Univ, Wales.
    Stekovic, Svjetlana
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Pattison, S. J.
    Rolls Royce Plc, England.
    Hyde, C. J.
    Univ Nottingham, England.
    Modelling the influence of plasticity induced softening on the low cycle fatigue and crack propagation behaviour of a nickel-based superalloy2024Ingår i: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 231, artikel-id 112604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cyclic hysteresis loops generated during high-temperature, isothermal, low-cycle fatigue testing of the nickel-based superalloy RR1000 revealed a gradual decrease in elastic modulus of up to 25 % compared to the initial value in dependence of the accumulated plastic strain. Based on the experimental observations, a material model was developed and implemented within a finite element solver to investigate the effect of degrading stiffness on crack growth laws and crack growth predictions. It was shown that the stress intensity factor diminished by 6 to 8 % and crack growth rates were 14 to 20 % higher when stiffness degradation was accounted for.

  • 15.
    Chai, Guocai
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    Siriki, Raveendra
    Alleima AB, Sweden.
    Wang, Qingyuan
    Chengdu Univ, Peoples R China.
    On fatigue crack origin with a fine granular area in matrix without defect2024Ingår i: Materialia, E-ISSN 2589-1529, Vol. 33, artikel-id 102004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fatigue crack initiation in metallic materials during very high cycle fatigue has been characterized by a subsurface crack origin with defect such as an inclusion. In this paper, fatigue damage behavior in an austenitic stainless steel has been studied using a novel progressive stepwise load increasing test method with each cycle step higher than 108 cycles. Subsurface crack origin with a fine granular area has formed in the matrix without defect. This is a new phenomenon. The mechanism has been investigated using Focused Ion Beam crosssectioning and electron channeling contrast imaging techniques. Strain localization, grain fragmentation and local plasticity exhaustion are the main factors that cause fatigue damage and crack initiation in the matrix. This study provides a fundamental understanding how material damage and crack initiation occur in material matrix during very high cycle fatigue.

  • 16.
    Zhu, Zhenyu
    et al.
    Chengdu Univ, Peoples R China.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Chengdu Univ, Peoples R China.
    Zhang, Junliang
    PetroChina Southwest Oil & Gas Field CDB Operating, Peoples R China.
    Li, Xiaotao
    Chengdu Univ, Peoples R China.
    Huang, Yanyan
    Chengdu Univ, Peoples R China.
    Zhang, Jie
    Southwest Jiaotong Univ, Peoples R China.
    Yu, Chao
    Southwest Jiaotong Univ, Peoples R China.
    Wang, Qingyuan
    Chengdu Univ, Peoples R China.
    Origin of prestrain-induced cyclic-strain hardening: Multi-scale experimental characterizations and simulations of 7075 aluminum alloy2024Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 238, artikel-id 112711Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of prefabricated dislocation features induced by rate dependent prestrain on the post-cyclic process in 7075 aluminum alloy exhibits significant variations, which are of great importance in terms of concerns, designs, and discoveries. Considering strain rate dependent prestrain provides diversified hardening stimuli for the subsequent cyclic process. The maximum cyclic stress in the post-cyclic stage was maintained at the same level as the prestress with strain rates ranging from 10-4s-1 to 10-1s-1. Subsequently, by adjusting post-cycling stress amplitude, research was conducted on quasi-plastic amplitude cycle (QPC) and low plasticity amplitude cycle (LPC) loading conditions. Through experimental mechanism analysis, as well as verification through molecular dynamics and crystal plasticity simulations, prestrain induced by rapid strain rates enhanced the hardening during QPC, stemming from the effects of matrix reconstruction strengthening and wavy structured grain boundaries. However, prestrain induced by slow strain rates promoted the hardening during LPC, primarily arising from the non-uniform crystal structures within individual grains, which was achieved through the complex sub-crystal clusters at grain boundaries, along with intracrystal orderly slipping lattice. These findings offer new insights for the optimization of microstructural design through dislocation engineering.

  • 17.
    Hu, Ji-Chong
    et al.
    Yantai Univ, Peoples R China.
    Huang, Hai-Liang
    Yantai Univ, Peoples R China.
    Wu, Chong-Chong
    Yantai Univ, Peoples R China.
    Sun, Xiao-Yu
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Wang, Jie
    Yantai Univ, Peoples R China.
    Yang, Yan-Hong
    Chinese Acad Sci, Peoples R China.
    Qu, Jing-Long
    Gaona Aero Mat Co Ltd, Peoples R China.
    Jiang, Liang
    Yantai Univ, Peoples R China.
    Dou, Jin-He
    Shandong First Med Univ & Shandong Acad Med Sci, Peoples R China.
    Chen, Yang
    Yantai Univ, Peoples R China.
    Oxidation behavior of Ni-based superalloy GH4738 under tensile stress2024Ingår i: Rare Metals, ISSN 1001-0521, E-ISSN 1867-7185, artikel-id s12598-024-02715-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Revealing the oxidation behavior of superalloys is crucial for optimizing material properties and extending service life. This study investigated the oxidation behavior of superalloy GH4738 under stress states at 850 degrees C. High-throughput specimens were fabricated to withstand different stresses at the same time. Isothermal oxidation samples were analyzed using the mass gain method to obtain oxidation kinetic curves. The results show that the external stress below 200 MPa could improve the oxidation resistance of the GH4738. With tensile stress increasing, the oxide layer becomes thinner, denser and more complete, while internal oxidation decreases. The tensile stress alters the structure of the external oxide layer from a two-layer to a three-layer configuration. The Cr2O3 oxide layer inhibits the outward diffusion of Ti, leading to Ti enrichment at the oxide-matrix interface and altering the oxidation mechanism of GH4738.

  • 18.
    Schwerz, Claudia
    et al.
    Chalmers Univ Technol, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Kung, Alain
    Fed Inst Metrol METAS, Switzerland.
    Bircher, Benjamin A.
    Fed Inst Metrol METAS, Switzerland.
    Riabov, Dmitri
    Chalmers Univ Technol, Sweden; Hoganas AB, Sweden.
    Nyborg, Lars
    Chalmers Univ Technol, Sweden.
    Reduction of oxygen content in laser powder bed fusion process atmosphere - Effects on stochastic defect formation and mechanical properties2024Ingår i: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, ISSN 2238-7854, Vol. 30, s. 4667-4681Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stochastic defects in materials manufactured via laser powder bed fusion (LPBF) can severely compromise mechanical performance and are challenging to predict and detect, thus motivating the development of defect mitigation strategies. Particle oxidation is a factor well-known to generate defects by disturbing melt pool dynamics. If the particles are spatters, additional disturbances increase the likelihood of defect formation. In this study, restricting oxygen content in the process atmosphere to 50 ppm is investigated to minimize stochastic spatter-induced defects and improve the mechanical properties of Hastelloy X. Specimens were manufactured under this condition at two nominal layer thicknesses, analyzed for internal defects, and mechanically tested. Contrary to expectations, reducing the oxygen content did not prevent spatter-induced defect formation; rather, it could exacerbate the formation of more numerous and larger defects. Nevertheless, this tighter control of the process atmosphere led to significant microstructural refinement, which, when combined with sparse defects, resulted in improved fatigue performance. Despite the inherent ductility of Hastelloy X, the presence of abundant defects significantly larger than the microstructural characteristic size proved detrimental to fatigue performance. Notably, the occurrence of defects exhibited considerable variation across the build area, contributing to scatter in fatigue data. However, quantitative analysis of in-situ monitoring data enabled prediction of variability in defect content and mechanical performance.

  • 19.
    Sun, Xiaoyu
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Li, Xiaolong
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg, Sweden.
    Guo, Sheng
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg, Sweden.
    Yu, Xin
    Institute for Advanced Studies in Precision Materials, Yantai University, Yantai, Shandong, China.
    Zhu, Lilong
    Institute for Advanced Studies in Precision Materials, Yantai University, Yantai, Shandong, China.
    Teng, Jianwei
    Institute for Advanced Studies in Precision Materials, Yantai University, Yantai, Shandong, China.
    Jiang, Liang
    Institute for Advanced Studies in Precision Materials, Yantai University, Yantai, Shandong, China.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Li, Xin-Hai
    Siemens Energy AB, SE-61283 Finspång, Sweden.
    Peng, Ru Lin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Revealing microstructural degradation mechanism induced by interdiffusion between Amdry365 coating and IN792 superalloy2024Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 241, artikel-id 112937Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Metallic coatings are widely employed to improve the oxidation resistance of superalloys. However, the interdiffusion between the metallic coatings and the superalloys leads to microstructural degradation in both. Some of the underlying degradation mechanisms are still elusive, e.g., the γ′ (Ni3Al) phase depletion in superalloys, where a large amount of γ′ precipitates are dissolved in the γ matrix even though the incoming Al from coatings indeed increases the Al content. Here, we investigated the interdiffusion behavior between the Amdry365 coating and the IN792 superalloy at 1100 °C, using multiple microscopic techniques and thermodynamics calculations. Our results showed an excellent agreement between experiments and thermodynamics simulations, indicating the dominant role of Al on the initial diffusion-induced phase transitions. We proposed the Al-Cr interference effect to account for the pile-up behavior of Cr and the reduced Al content near the coating/superalloy interface. The local phase equilibrium calculations revealed that the γ′ depletion in the superalloy is primarily attributed to the loss of γ′-forming elements, such as Ta and Ti. Our findings opened up an avenue for studies on the superalloy/coating interdiffusion, contributing to reducing this damaging impact.

  • 20.
    Nordström, Joakim
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    Dong, Zhihua
    Department of Materials Science and Engineering, KTH, Sweden; Material Science and Engineering, Chongqing University, China.
    Lautrup, Lisa
    Alleima AB, Sweden.
    Siriki, Raveendra
    Alleima AB, Sweden.
    Vitos, Levente
    Department of Materials Science and Engineering, KTH, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    Temperature study of deformation twinning behaviour in Nickel-base Superalloy 6252024Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, artikel-id 146628Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deformation behaviour in the Nickel-base superalloy 625 has been studied by tensile testing at four temperatures: 295, 223, 173 and 77 K. The microstructure has been investigated using TEM, FIB-SEM, EBSD and ECCI techniques. Deformation in the alloy turns out to be a competitive course of events between at least two deformation mechanisms, namely dislocation slip and deformation twinning. Slip is the predominant deformation mechanism at higher temperatures. While at 77 K, deformation induced twinning gives an extra degree of freedom as one of the main deformation mechanisms, i.e., the material shows a twin induced plasticity, TWIP, behaviour. Ab initio calculations indicate that the influence of cryogenic/sub-zero temperatures on the stacking fault energy of this alloy can be limited and that the formation of deformation twins cannot be determined solely by the stacking fault energy. The results implies that it is the critical strain and strain hardening rate that influences the deformation twinning onset and twinning rate.

  • 21.
    Zaikovska, Liene
    et al.
    Univ West, Sweden.
    Ekh, Magnus
    Chalmers Univ Technol, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Univ West, Sweden.
    Three-Dimensional Columnar Microstructure Representation Using 2D Electron Backscatter Diffraction Data for Additive-Manufactured Haynes®282®2024Ingår i: Materials, E-ISSN 1996-1944, Vol. 17, nr 7, artikel-id 1659Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study provides a methodology for exploring the microstructural and mechanical properties of the Haynes (R) 282 (R) alloy produced via the Powder Bed Fusion-Electron Beam (PBF-EB) process. Employing 2D Electron Backscatter Diffraction (EBSD) data, we have successfully generated 3D representations of columnar microstructures using the Representative Volume Element (RVE) method. This methodology allowed for the validation of elastic properties through Crystal Elasticity Finite Element (CEFE) computational homogenization, revealing critical insights into the material behavior. This study highlights the importance of accurately representing the grain morphology and crystallographic texture of the material. Our findings demonstrate that created virtual models can predict directional elastic properties with a high level of accuracy, showing a maximum error of only similar to 5% compared to the experimental results. This precision underscores the potential of our approach for predictive modeling in Additive Manufacturing (AM), specifically for materials with complex, non-homogeneous microstructures. It can be concluded that the results uncover the intricate link between microstructural features and mechanical properties, underscoring both the challenges encountered and the critical need for the accurate representation of grain data, as well as the significance of achieving a balance in EBSD area selection, including the presence of anomalies in strongly textured microstructures.

  • 22.
    Pupurs, A.
    et al.
    Riga Tech Univ, Latvia.
    Sahbi Loukil, Mohamed
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. RISE Res Inst Sweden, Sweden.
    Marklund, E.
    RISE Res Inst Sweden, Sweden.
    Varna, J.
    Riga Tech Univ, Latvia; Lulea Univ Technol, Sweden.
    Mattsson, D.
    RISE Res Inst Sweden, Sweden.
    Transverse Crack Initiation in Thin-Ply Laminates Subjected to Tensile Loading at Low and Cryogenic Temperatures2024Ingår i: Mechanics of composite materials, ISSN 0191-5665, E-ISSN 1573-8922, s. 1049-1064Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laminates with ultra-thin plies is a promising new development for polymeric composite materials expected to provide superior resistance to intralaminar crack propagation. The ply thickness effect on the crack initiation stress that according to some theoretical studies on fiber/matrix debonding does not depend on the ply thickness was investigated. Ultra-thin ply carbon fiber/epoxy cross-ply laminates subjected to tensile loading at room, -50, and -150 degrees C temperatures relevant for cryogenic fuel storage, aeronautical, and aerospace applications were studied. The stochastic nature of the crack initiation stress in the 90 degrees-plies was analyzed using Weibull strength distribution. The results obtained show delayed transverse crack initiation only in the thinnest plies with a clear trend that the scale parameter is much larger. This thickness effect on initiation is different than that for crack propagation which is observable in much larger ply thickness range. Regarding crack propagation, it was found that in most cases even at very high applied strain levels (1.5%) only a few transverse cracks have propagated from the specimen edges to its middle.

  • 23.
    Sun, Xiaoyu
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Cent South Univ, Peoples R China.
    Zhang, Longfei
    Cent South Univ, Peoples R China.
    Pan, Yanming
    Cent South Univ, Peoples R China.
    Zhu, Lilong
    Yantai Univ, Peoples R China.
    Huang, Zaiwang
    Cent South Univ, Peoples R China.
    Jiang, Liang
    Yantai Univ, Peoples R China.
    Tuning Mo/W ratio to improve high temperature oxidation resistance of single crystal nickel base superalloys2024Ingår i: Materials Today Communications, ISSN 2352-4928, Vol. 38, artikel-id 107826Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of different Mo/W ratios of three single crystal nickel base superalloys on the oxidation behavior was investigated at 1100 degrees C. Both isothermal and cyclic oxidation tests showed that increasing Mo/W ratio corresponds to lower weight change and improved resistance. The microscopic observation uncovers that the harmful effect of Mo is limited by the dense Al2O3 scale. In contrast, excessive W leads to fast growth of interlayer and its premature spallation. This research proposes and verifies a new way to improve oxidation resistance of alloy, namely, balancing the harmful effect of refractory elements.

  • 24.
    Gupta, M.
    et al.
    Univ West, Sweden.
    Li, X. -H
    Siemens Energy AB, Sweden.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Ottosson, A.
    GKN Aerosp Sweden AB, Sweden.
    Gillberg, P.
    Curtiss Wright Surface Technol AB, Sweden.
    Girgulis, J.
    Oerlikon Metco AG, Switzerland.
    Understanding the effect of bondcoat surface treatment on enhanced lifetime of suspension plasma sprayed thermal barrier coatings2024Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 482, artikel-id 130716Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal barrier coatings (TBCs) are extensively used in gas turbine engines in power generation and aerospace applications. Improvements in TBC performance and lifetime are continuously pursued by the gas turbine industry. Suspension plasma spraying (SPS) has shown promising results in recent years as it could produce a porous columnar TBC microstructure exhibiting low thermal conductivity and high durability. Further improvements in lifetime and fundamental understanding of failure mechanisms would lead to their wider application. Lifetime of a TBC system is dependent not only on the topcoat microstructure and chemistry, but also on topcoat-bondcoat interface and bondcoat characteristics as they influence the growth rate of thermally grown oxide (TGO) layer as well as the mismatch stresses generated in the topcoat during operation. Moreover, in SPS TBCs, the column density and porosity in the topcoat are also affected by the bondcoat surface roughness which in turn affects TBC lifetime. In previous work, it was shown that bondcoat surface treatment by shot peening followed by light grit blasting can significantly enhance the cyclic lifetime of SPS TBCs. The objective of this work was to gain further insight into the lifetime improvements due to surface treatment of bondcoat. Commercial NiCoCrAlY powder was deposited by high velocity air fuel (HVAF) and high velocity oxy fuel (HVOF) spraying while SPS was used to deposit yttria stabilised zirconia topcoat. Before spraying the topcoat, the bondcoat samples were subjected to vacuum heat treatment, shot peening, and/or grit blasting. Residual stress measurements were performed by X-ray diffraction on samples with different variants of bondcoat treatments and compared with Almen strip tests. The lifetime was examined by thermal cyclic fatigue testing. The relationships between changes in bondcoat surface roughness, residual stress state and microstructure due to surface treatments, and resultant topcoat microstructure and lifetime were studied and discussed.

  • 25.
    Lindvall, Rebecka
    et al.
    Lund Univ, Sweden.
    Diaz, Kevin Monroe
    Lund Univ, Sweden.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Gutnichenko, Oleksandr
    Lund Univ, Sweden.
    Siren, Sebastian
    Volvo Grp Trucks Operat, Sweden.
    Aberg, Lena Magnusson
    Volvo Grp Trucks Operat, Sweden.
    Norgren, Susanne
    Lund Univ, Sweden; Sandvik Coromant R&D, Sweden.
    M'Saoubi, Rachid
    Lund Univ, Sweden; R&D Materials& Technol Dev, Sweden.
    Bushlya, Volodymyr
    Lund Univ, Sweden.
    Stahl, Jan-Eric
    Lund Univ, Sweden.
    Wear mechanisms in Ti(C,N)-Al2O3 coated carbide during sustainable machining CGI2024Ingår i: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 119, artikel-id 106550Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By replacing conventional gray cast iron (GI) with compacted graphite iron (CGI), automotive industry could keep up with stricter regulations on emissions and demands on higher engine performance. CGI has improved properties as to GI but is more difficult to machine. This study evaluates sustainable machining performance during finish face milling when using minimum quantity lubrication applied vegetable oil, resulting in 8% or 17-23% improved tool life respectively as to dry conditions. The main part of the study investigates the wear mechanisms in commercial Ti(C,N)-Al2O3 CVD-coated cemented carbide. The coating degrades by mechanically induced cracking and fractures, oxidation of adhered CGI inside cracks, diffusional dissolution of Ti(C,N) layer. Formation of softer (Mg,Fe,Mn)Al2O4 spinel is not observed but could be an expected reaction product. Other oxide inclusions, when deposited on cemented carbide surfaces, prevents adhesion of CGI material, and can reduce the wear rate where they are present. CGI adhering to cemented carbide induces diffusional loss of cobalt and carbon that eventually forms (Fex,Co1-x)3C iron carbide at the tool-workpiece interface which can reduce the diffusion rate. Novel findings also relates to the formation of 15 mu m deep cracks in the cemented carbide due to inward diffusion of Fe accompanied by its oxidation that speeds up the oxygen ingress and further oxidation of W and Co. Oxidation was found to provide a positive effect when the adhered CGI completely oxidized to form Fe2SiO4 oxide ceramic Tool Protection Layer which slowed down tool material degradation.

  • 26.
    Sadeghi, Esmaeil
    et al.
    Univ Waterloo, Canada.
    Karimi, Paria
    Univ Waterloo, Canada.
    Esmaeilizadeh, Reza
    Univ Waterloo, Canada.
    Berto, Filippo
    Sapienza Univ Roma, Italy.
    Shao, Shuai
    Auburn Univ, AL 36849 USA; Auburn Univ, AL 36849 USA.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Toyserkani, Ehsan
    Univ Waterloo, Canada.
    Shamsaei, Nima
    Auburn Univ, AL 36849 USA; Auburn Univ, AL 36849 USA.
    A state-of-the-art review on fatigue performance of powder bed fusion-built alloy 7182023Ingår i: Progress in Materials Science, ISSN 0079-6425, E-ISSN 1873-2208, Vol. 133, artikel-id 101066Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Alloy 718 is a Ni-Fe-based superalloy, which has been successfully adapted to powder bed fusion (PBF) additive manufacturing because of the alloys adaptability with such emerging technology in achieving enhanced mechanical properties. Despite a promising perspective for PBF-built Alloy 718 in different industries, a few factors, including microstructural non-uniformities, volumetric defects, undesired non-metallic inclusions, anisotropic behavior, residual stress, as well as surface and sub-surface irregularities, lead to premature fatigue life of the parts. However, the PBF technology has been quickly growing, and associate progress has resulted in substantial advances in quality, hence increased fatigue life of the parts. Therefore, a critical assessment of the efficacy of the PBF-built Alloy 718 parts can be highly enlightening. A fundamental understanding of the relationship between feedstock material, manufacturing process, process parameters, microstructure, properties, and fatigue life of PBF-built Alloy 718 is crucial for improving the characteristics of the current materials, designing new alloy systems, and enhancing the capability of the PBF techniques. The present paper aims to comprehensively review the fundamentals and recent advances in the PBF-built Alloy 718 parts with improved fatigue life, the influence of thermal and mechanical post-treatment, mechanisms of fatigue crack initiation and growth, thermo-mechanical fatigue, dwell-time fatigue, as well as fracture behavior in different loading conditions and environments considering anisotropic characteristics of the material. An unbiased review of the literature provides an understanding of the advanced and outstanding achievements in the field that assure further research. An evaluation of the status of the field, the gaps in the theoretical understanding, and the fundamental needs for the sustainable development of PBFbuilt Alloy 718 with enhanced fatigue life in specific applications are also provided.

  • 27. Beställ onlineKöp publikationen >>
    Leijon, Freddy
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Aluminium alloy development for Additive Manufacturing2023Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Powder Bed Fusion (PBF Additive Manufacturing AM have emerged as a promising manufacturing process possessing a powerful combination of characteristics. Most noticeable are the near-net-shape, short lead time and flexibility, both with regard in design freedom and in part-to-part variation. Aluminium alloys are used in everything from food packaging, furniture's, to cars and airplanes. To accommodate for this wide range in material requirements, different alloys have been developed over the past century. To reach the full potential of AM, a thoroughly work lies ahead of the research community to find, tailor and refine alloys.

    This work has focused on experimentally screening of AM alloys, for their printability and potential properties. To accelerate this, a novel high through put method was first developed to efficiently produce a broad range of alloys both with respect to compositions and alloying elements. This method consists of two steps; in the first step a compositional alloy gradient film is deposited on an aluminium substrate, and in a second step a microstructure mimicking PBF is formed by either laser or electron beam melting of the film. Gradients up to 500mm in length ranging from 0-85wt% in alloying content were achieved. This enabled high resolution studies of the influence of alloying elements over wide compositional intervals. Various aspects of the material were possible to investigate such as: Grain size, hardness, printability, evaporation losses, solid solution, electrical conductivity and microstructure. The results were verified against the available literature, and a strong correlation between properties of the PBF mimicked materials and actual PBF materials were confirmed.

    With the developed screening method, printability i.e. the material's capacity to be processed in PBF without formation of cracks , could be studied and mapped out for a large set of alloys. The AlMgSi system were found to be printable without grain refinement if Si+Mg<0.7wt% or Si+2/3Mg>4wt% for Mg < 3wt% and Si > 3wt%. Investigations of Til-xMxB2 and Al3Til-xMx grain refiners in 2wt% Cu alloys reveled that grain refinement and printability strongly correlated to both x and the element M(Zr,Ta,V,W). However, no clear relationship between the grain size and the lattice parameters of Til-xMxB2 and Al3Til-xMx were found.

    In addition to mapping out printability, hardness as a function of composition was also mapped out for the binary alloys Al -Ti, -Zr, -Nb, -Sr and the AlMgSi system. Other important findings are that the Mg loss due to evaporation and the solid solution of Mg was found to depend linearly on the amount of Mg, and a transition from equiaxed to fine lamellar Al4Sr intermetallic going above 5wt%. Altogether, the screening method developed in this work offer a unique way to efficiently study composition dependent transitions in printability, microstructure and other material properties which are otherwise difficult to foresee or experimentally laborious to study.

    Delarbeten
    1. A novel rapid alloy development method towards powder bed additive manufacturing, demonstrated for binary Al-Ti, -Zr and -Nb alloys
    Öppna denna publikation i ny flik eller fönster >>A novel rapid alloy development method towards powder bed additive manufacturing, demonstrated for binary Al-Ti, -Zr and -Nb alloys
    Visa övriga...
    2021 (Engelska)Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 211, artikel-id 110129Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Powder bed fusion (PBF) methods offer the best material properties among metal additive manufacturing (AM) processes. Yet, alloy development for PBF is only at its infancy and has a great untapped potential. This originates from the high solidification rate within the melt pool and to exploit the full potential of materials produced by PBF methods, a diligent work lies ahead. This paper presents a high-throughput method to rapidly screen large compositional alloy intervals experimentally for their PBF feasibility, which can drastically reduce the time needed for alloy development and provide valuable data for modelling. Our method consists of two steps; co-sputtering and electron beam re-melting. First step produces an alloy gradient film on a sheet substrate. The film is then re-molted to produce a PBF mimicked microstructure. The method is successfully demonstrated on binary systems; Al-Ti,-Zr and-Nb and produced gradients in compositional ranges of 3-50 wt%Ti, 1-15 wt%Zr and 2-15 wt%Nb over a length of 200 mm. From the produced materials, the alloying efficiency could be investigated and determined regarding hardness and grain refinement. Zr shows the highest strength contribution per at% and the best grain refinement at low levels. However, at higher levels grain refinement efficiency decreases for Zr. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

    Ort, förlag, år, upplaga, sidor
    Elsevier Science Ltd, 2021
    Nyckelord
    High through put method; Aluminium alloys; Powder bed fusion; Additive manufacturing; Electron Beam
    Nationell ämneskategori
    Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-180511 (URN)10.1016/j.matdes.2021.110129 (DOI)000706882800002 ()
    Anmärkning

    Funding Agencies|Norsk Hydro ASA; Carl Tryggers Foundation for Scientific Research [CTS 15:219, CTS 14:431]

    Tillgänglig från: 2021-10-25 Skapad: 2021-10-25 Senast uppdaterad: 2023-04-18
    2. Investigation of Ti-1_x(Zr,Ta,V,W)(x)B-2 and A(l3)Ti(1_x)(Zr,V)(x) grain refiners in additively manufactured Al-2 wt%Cu alloys by a high throughput method
    Öppna denna publikation i ny flik eller fönster >>Investigation of Ti-1_x(Zr,Ta,V,W)(x)B-2 and A(l3)Ti(1_x)(Zr,V)(x) grain refiners in additively manufactured Al-2 wt%Cu alloys by a high throughput method
    Visa övriga...
    2022 (Engelska)Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 222, artikel-id 111093Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Grain refinement plays a central role in powder bed fusion (PBF) additive manufacturing by preventing hot cracking and thus enabling the development of high-strength alloys. However, the mechanism behind grain refinement is not fully understood for conventional casting, nor for PBF. In this work, a high throughput method have been used to produce Al-2 wt%Cu alloys with additions of Ti1-xM(Zr,Ta,V,W)(x)B-2, Al3Ti1-xM(Zr,V)(x) or AlB2 grain refiners for 0.1 &lt; x &lt; 0.9. It was found that grain size varied with x, M and the sum of Ti + M. Ti1-xMxB2 grain refiners offered no advantage over Al3Ti1-xMx. Overall, Ti and Zr provide the best grain refinement, both as Ti1-xMxB2 and Al3Ti1-xMx. However, Ti1-xZrxB2 had a grain refinement minimum around x = 0.65-0.70. The behavior was similar with Ta, but to a lesser extent. V and W had detrimental effects on grain refinement. Despite the fact that no AlB2 particles were observed, additions of B provided excellent grain refinement and was more efficient than Ti below 0.5at%. Ti1-xMxB2 lattice parameters varied with x and followed Vegards law, however, a clear relationship between grain size and epitaxial strain/lattice match could not be established. Similarly, the growth restricting factor alone was not a predictor of grain size.

    Ort, förlag, år, upplaga, sidor
    Elsevier Science Ltd, 2022
    Nationell ämneskategori
    Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-188764 (URN)10.1016/j.matdes.2022.111093 (DOI)000855347300002 ()
    Anmärkning

    Funding Agencies|Norsk Hydro ASA; Centre in Nanoscience and Technology at LiTH. Carl Tryggers Foundation for Scientific Research [CTS 14:431]; AMEXCI AB; [CTS 15:219]

    Tillgänglig från: 2022-09-26 Skapad: 2022-09-26 Senast uppdaterad: 2023-04-18
    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner (png)
    presentationsbild
  • 28.
    Souissi, Moez
    et al.
    Univ Sfax, Tunisia.
    Trigui, Abdelwaheb
    Univ Sfax, Tunisia.
    Jedidi, Ilyes
    Univ Sfax, Tunisia; Univ Technol & Appl Sci Sohar, Oman.
    Loukil, Mohamed Sahbi
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Abdelmouleh, Makki
    Univ Sfax, Tunisia.
    Bio-based composite as phase change material including spent coffee grounds and beeswax paraffin2023Ingår i: Korean Journal of Chemical Engineering, ISSN 0256-1115, E-ISSN 1975-7220, Vol. 40, nr 9, s. 2342-2355Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New types of bio-composite phase change materials (BCPCM) with improved thermal properties were made from spent ground coffee powder (C), beeswax (W) and low density polyethylene (LDPE). Beeswax is a relatively accessible phase change material of organic origin, with a significantly lower unit price compared to conventional phase change materials (PCM). The observations by SEM and FTIR spectroscopy showed that the BCPCMs were physically combined. Through these techniques, it was discovered that ground coffee was effectively impregnated with natural wax and LDPE. According to the thermal gravimetric analysis (TGA), the thermal stability of BCPCM was improved, due to the use of waste coffee grounds, in the working temperature range. The biocomposite possesses excellent performance as characterized by 136.9 J/g (W70C10PE20)&gt;, 127.31 J/g (W70C20PE10)&gt;, 126.95 J/g (W70C30)&gt;, 121.08 J/g (W70PE30) of latent heat storage and tends to decrease the supercooling degree as compared with pure beeswax during melting/solidification process. By adding LDPE to the PCM, the melting time is reduced, demonstrating an improvement in thermal energy storage (TES) reaction time to the demand. The experimental results showed that the fraction of oils (12%) in spent ground coffee powder can participate in the improvement of the thermal properties of BCPMC. The use of biocompatible PCM by-products is suitable for applications in the field of heat storage because it is affordable and environmentally beneficial.

  • 29.
    Huang, Shuo
    et al.
    China Univ Geosci, Peoples R China; China Univ Geosci, Peoples R China.
    Dastanpour, Esmat
    Royal Inst Technol, Sweden.
    Schonecker, Stephan
    Royal Inst Technol, Sweden.
    Strom, Valter
    Royal Inst Technol, Sweden.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. AB Sandvik Mat Technol R& D Ctr, Sweden.
    Kiss, Laszlo Ferenc
    Wigner Res Ctr Phys, Hungary.
    Varga, Lajos Karoly
    Wigner Res Ctr Phys, Hungary.
    Jin, Hongyun
    China Univ Geosci, Peoples R China.
    Eriksson, Olle
    Uppsala Univ, Sweden; Orebro Univ, Sweden.
    Vitos, Levente
    Royal Inst Technol, Sweden; Wigner Res Ctr Phys, Hungary; Uppsala Univ, Sweden.
    Combinatorial design of partial ordered Al-Cr-Mn-Co medium-entropy alloys for room temperature magnetic refrigeration applications2023Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 123, nr 4, artikel-id 044103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multi-component alloys have received increasing interest for functional applications in recent years. Here, we explore the magnetocaloric response for Al-Cr-Mn-Co medium-entropy alloys by integrated theoretical and experimental methods. Under the guidance of thermodynamic and ab initio calculations, a dual-phase system with large magnetic moment, i.e., Al50Cr19Mn19Co12, is synthesized, and the structural and magnetocaloric properties are confirmed via characterization. The obtained results indicate that the selected alloy exhibits a co-continuous mixture of a disordered body-centered cubic and an ordered B2 phase. The ab initio and Monte Carlo calculations indicate that the presence of the ordered B2 phase is responsible for the substantial magnetocaloric effect. The magnetization measurements demonstrated that this alloy undergoes a second-order magnetic transition with the Curie temperature of similar to 300 K. The magnetocaloric properties are examined using magnetic entropy change, refrigeration capacity, and adiabatic temperature change. The property-directed strategy explored here is intended to contribute to the study of potential multi-component alloys in magnetocaloric applications.

  • 30.
    Chai, Guocai
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima, Sweden.
    Bergström, Jens
    Karlstad Univ, Sweden.
    Burman, Christer
    Karlstad Univ, Sweden.
    Crack Initiation in Bulk Matrix of Austenitic Stainless Steel during Very High Cycle Fatigue2023Ingår i: Materials Performance and Characterization, ISSN 2379-1365, E-ISSN 2165-3992, Vol. 12, nr 2, artikel-id MPC20220094Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the very high cycle fatigue regime, fatigue crack initiation in high-strength steels is usually correlated to a subsurface inclusion with a fine granular area (FGA). Localized stress-strain concentration at the subsurface inclusion is a critical factor. Fatigue crack initiation with an FGA in the bulk matrix without any defect has rarely been reported. In this paper, a fundamental study on the formation of FGAs in the bulk matrix of an austenitic stainless steel has been carried out using a progressive stepwise load-increasing test with a cycle step of about 108 cycles. FGA formation in the subsurface bulk matrix has been observed. The micro structural damage in the fatigue-tested specimens has been studied using the electron channeling contrast imaging electron microscopy technique. Strain localization and grain fragmentation are the main processes for the formation of FGAs. Local plasticity exhaustion leads to crack initiation due to local stress concentrations. This method can also be used to predict the fatigue damage process, especially the damage rate in individual specimens.

  • 31.
    Jiang, S.
    et al.
    Northeastern Univ, Peoples R China.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Zhao, X.
    Northeastern Univ, Peoples R China.
    Zuo, L.
    Northeastern Univ, Peoples R China.
    Jia, N.
    Northeastern Univ, Peoples R China.
    Deformation incompatibility enables hetero-deformation induced strengthening in Ti/Nb laminates2023Ingår i: Materials Research Letters, E-ISSN 2166-3831, Vol. 11, nr 2, s. 126-133Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    IMPACT STATEMENT The phase-to-phase interaction is found to be an important indicator for evaluating the HDI strengthening and hardening in heterogeneous laminates, and the microstress analysis can guide the design of heterostructures. Deformation incompatibility in Ti/Nb laminates under uniaxial tension was revealed by in-situ neutron diffraction. During uniform deformation of the bulk laminates, the hard Nb constrained by the soft Ti showed moderate work hardening and only slightly decreased flow stress. The mechanical incompatibility accumulated in both elastic and elasto-plastic regimes between the metals lead to pronounced hetero-deformation induced (HDI) strengthening, and the HDI stress was comparable to the maximum phase-to-phase interaction. The HDI hardening and interphase stress showed consistent evolution trends, implying that the interaction between dissimilar metals can be used as an important indicator for evaluating HDI strengthening and hardening.

    Ladda ner fulltext (pdf)
    fulltext
  • 32.
    Hozić, Dženan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. RISE Research Institutes of Sweden, Division of Materials and Production, Polymers, Fibers and Composites Department, Box 857, Borås, 501 15, Sweden.
    Thore, Carl-Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Cameron, Christopher
    RISE Research Institutes of Sweden, Division of Materials and Production, Polymers, Fibers and Composites Department, Box 857, Borås, 501 15, Sweden.
    Loukil, Mohamed Sahbi
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Deterministic-based robust design optimization of composite structures under material uncertainty2023Ingår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 322, artikel-id 117336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a new deterministic robust design optimization method for composite laminate structures under worst-case material uncertainty. The method is based on a simultaneous parametrization of topology and material and combines a design problem and a material uncertainty problem into a single min–max optimization problem which provides an efficient approach to handle variation of material properties in stiffness driven design optimization problems. An analysis is performed using a design problem based on a failure criterion formulation to evaluate the ability of the proposed method to generate robust composite designs. The design problem is solved using various loads, boundary conditions and manufacturing constraints. The designs generated with the proposed method have improved objective responses compared to the worst-case response of designs generated with nominal material properties and are less sensitive to the variation of material properties. The analysis indicates that the proposed method can be efficiently applied in a robust structural optimization framework. © 2023 The Author(s)

    Ladda ner fulltext (pdf)
    fulltext
  • 33.
    Pauzon, Camille
    et al.
    Chalmers Univ Technol, Sweden; Univ Grenoble Alpes, France; Chalmers Univ Technol, Sweden; Univ Grenoble Alpes, France.
    Raza, Ahmad
    Chalmers Univ Technol, Sweden.
    Hanif, Imran
    Chalmers Univ Technol, Sweden.
    Dubiez-Le Goff, Sophie
    Linde AG EMEA, Germany.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Hryha, Eduard
    Chalmers Univ Technol, Sweden.
    Effect of layer thickness on spatter properties during laser powder bed fusion of Ti-6Al-4V2023Ingår i: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 66, nr 4, s. 333-342Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High layer thicknesses for laser powder bed fusion are promising for productivity increase. However, these are associated with increased process instability, spatter generation and powder degradation, crucial for alloys sensitive to oxygen. The effect of increasing layer thickness from 30 to 60 mu m is studied focusing on Ti-6Al-4V spatter formation during LPBF and its characterisation, with scanning and transmission electron microscopy, combustion analysis and X-ray photoelectron spectroscopy. Results indicate that spatters are covered with a uniform Ti-Al-based oxide layer and Al-rich oxide particulates, the thickness of which is about twice that present on virgin powder. The oxygen content was about 60% higher in spatters compared to the virgin powder. The study highlights that increasing the layer thickness to 60 mu m permits to reduce the total generation of spatters by similar to 40%, while maintaining similar spatter characteristics and static tensile properties. Hence, this allows to increase build rate without compromising process robustness.

    Ladda ner fulltext (pdf)
    fulltext
  • 34.
    Chai, Guocai
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Sandvik Mat Technol, Sweden.
    Bergstrom, Jens
    Karlstad Univ, Sweden.
    Burman, Christer
    Karlstad Univ, Sweden.
    Formation of fine granular area in a non-defect matrix of austenitic stainless steel during very high cycle fatigue2023Ingår i: Fatigue & Fracture of Engineering Materials & Structures, ISSN 8756-758X, E-ISSN 1460-2695, Vol. 46, nr 6, s. 2364-2373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fine granular area, FGA, is a typical phenomenon observed at the very high cycle fatigue fracture crack origin with a subsurface defect in the material. The FGA has been widely investigated, and different mechanisms have been proposed. In this paper, the formation of FGA in a non-defect matrix of one austenitic steel during very high cycle fatigue was studied using a progressive stepwise load-increasing method and electron scanning microscopy/electron channeling contrast imaging (ECCI) technique. A nano rough surface area or FGA at the fatigue crack origin has been observed in the subsurface matrix without any defect. It is a new phenomenon. A mechanism was proposed using the dislocation plasticity theory. The formation of FGA in a non-defect matrix is a localized plasticity exhausting process by strain localization, grain fragmentation, stress concentration and nano crack initiation and propagation along low-angle grain boundaries.

    Ladda ner fulltext (pdf)
    fulltext
  • 35.
    Dong, Han
    et al.
    Shanghai Univ, Peoples R China.
    Chai, Guocai
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Alleima AB, Sweden.
    Guo, Xiaofei
    Shanghai Univ, Peoples R China.
    High Nitrogen Steels2023Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 94, nr 10, artikel-id 2300505Artikel i tidskrift (Övrigt vetenskapligt)
  • 36.
    Leijon, Freddy
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Hydro Extruded Solut AB, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    High-Throughput Printability Screening of AlMgSi Alloys for Powder Bed Fusion2023Ingår i: Metals, ISSN 2075-4701, Vol. 13, nr 6, artikel-id 1114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The importance of both recycling and additive manufacturing (AM) is increasing; however, there has been a limited focus on the development of AM alloys that are compatible in terms of recyclability with the larger scrap loops of wrought 5xxx, 6xxx and cast 3xx aluminium alloys. In this work, the powder bed fusion (PBF) printability of AlMgSi alloys in the interval of 0-30 wt% Mg and 0-4 wt% Si is screened experimentally with a high-throughput method. This method produces PBF-mimicked material by PVD co-sputtering, followed by laser remelting. Strong evidence was found for AlMgSi alloys being printable within two different composition ranges: Si + Mg &lt; 0.7 wt% or for Si + 2/3 Mg &gt; 4 wt% when Mg &lt; 3 wt% and Si &gt; 3 wt%. Increasing the amount of Mg and Si influences the grain structure by introducing fine columnar grains at the melt pool boundary, although the melt pool interior was unaffected. Hardness in an as-built state increased with both Mg and Si, although Si had a neglectable effect at low levels of Mg. Both the evaporative loss of Mg and the amount of Mg in solid solution increased linearly with the amount of Mg.

    Ladda ner fulltext (pdf)
    fulltext
  • 37.
    Sun, Xiaoyu
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Zhang, Pimin
    Alloyed-OxMet Technologies, OX5 1QU Oxford, England, United Kingdom.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Li, Xin-Hai
    Siemens Energy AB, SE-61283 Finspång, Sweden.
    Cui, Luqing
    School of Mechanical Engineering, Xi'an Jiaotong University, 710049, Xi'an, China.
    Peng, Ru Lin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Impeding the γ' depletion during the interdiffusion between bond coatings and superalloys via introduction of tantalum in bond coatings2023Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 227, artikel-id 111792Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of aluminiferous coatings profoundly improves the service life of superalloys but leads to microstructural degradation of superalloys and thus loss of mechanical properties. In this study, we mod- ified MCrAlY coatings by adding Ta to reduce the interdiffusion effect on substrate alloys. This strategy was verified by 2000 h/1100 °C oxidation tests in two Ta-containing MCrAlY-IN792 systems. The system with 3.3 wt% Ta MCrAlY exhibits an outstanding resistance to c0 depletion in the substrate and compa- rable oxidation property in comparison with a reference system of Ta-free MCrAlY-IN792. Increasing Ta to 7.4 wt% results in reduced oxidation resistance. Thermodynamic simulations revealed the phase- transformation mechanism induced by initial interdiffusion, uncovering the cause of c0 depletion in the substrate and the mechanism behind improving resistance to c0 depletion by Ta addition.

    Ladda ner fulltext (pdf)
    fulltext
  • 38.
    Lindstrom, Stefan B.
    et al.
    Mid Sweden Univ, Sweden.
    Wemming, Hannes
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. Saab AB, S-58188 Linkoping, Sweden.
    Kapidzic, Zlatan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. Saab AB, S-58188 Linkoping, Sweden.
    Sahbi Loukil, Mohamed
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Segersäll, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Integrated digital image correlation for mechanical characterization of carbon fiber-reinforced polymer plates2023Ingår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 305, artikel-id 116501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use integrated digital image correlation (IDIC) with gradient-free optimization to identify the in-plane, linear-elastic material parameters of carbon fiber-reinforced polymer (CFRP) plates. With IDIC, a monolithic least-squares problem is formulated, based on the video capture of a tension/compression test, with the material parameters as unknowns. Transverse deformations are induced by using holeplate specimens, so that all parameters are identified with one tensile test. We also demonstrate how an invariant-based CFRP model, parameterized by the Tsai modulus, further enhances the robustness of IDIC characterization.

    Ladda ner fulltext (pdf)
    fulltext
  • 39.
    Hozic, Dzenan
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. RISE Res Inst Sweden, Sweden.
    Thore, Carl-Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Cameron, Christopher
    RISE Res Inst Sweden, Sweden.
    Sahbi Loukil, Mohamed
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Material uncertainty quantification for optimized composite structures with failure criteria2023Ingår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 305, artikel-id 116409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a method to analyze effects of material uncertainty in composite laminate structures optimized using a simultaneous topology and material optimization approach. The method is based on computing worst -case values for the material properties and provides an efficient way of handling variation in material properties of composites for stiffness driven optimization problems. An analysis is performed to evaluate the impact of material uncertainty on designs from two design problems: Maximization of stiffness and minimization of a failure criteria index, respectively. The design problems are solved using different loads, boundary conditions and manufacturing constraints. The analysis indicates that the influence of material uncertainty is dependent on the type of optimization problem. For compliance problems the impact on the objective value is proportional to the changes of the constitutive properties and the effect of material uncertainty is consistent and predictable for the generated designs. The strength-based problem shows that material uncertainty has a significant impact on the response, and the effects of material uncertainty is not consistent and changes for different design requirements. In addition, the results show an increase of up to 25% of the maximum failure index when considering the worst-case deviation of the constitutive properties from their nominal values.

    Ladda ner fulltext (pdf)
    fulltext
  • 40.
    Torsteinsrud, Oscar
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial.
    Reijm, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial.
    Metals for energy storage: For hydrogen and power generation2023Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With an increase in energy demand and a transition from conventional fossil-driven energy generation, the world is facing a major challenge. This transition implies more intermittent energy sources whose reliance varies widely with time. To deal with this challenge, energy storage is one part of the solution. By storing energy when the supply is higher than the demand, it can later be used when the demand is higher than the supply. This could be done in numerous ways but this study aims to analyze the theoretical performance of metals for energy storage. 

    This was done for five different metals and metal-like elements. The metals studied were aluminum, boron, magnesium, silicon and zinc. The basic principle of using metals for energy storage involves a couple of steps. Firstly, energy is supplied to the metal through a reduction reaction, charging the system. After this process, the metal can be stored and thus also the energy. When the energy is needed, the energy can be released through an oxidation reaction. The products of this will be hydrogen and heat that in a later conversion process can generate electrical energy. The performance of each metal was analyzed based on round trip efficiency, energy density and CO2 emissions. To evaluate this, a model was built in IPSEpro. 

    The results of the study indicate that zinc performs the best in terms of round-trip efficiency while boron has the highest energy density and magnesium has the lowest amount of CO2 emissions. However, what may be more interesting is that the performance of all the metals is relatively similar to each other. The general trend is that the large advantage of using metals for energy storage is the immense energy density meaning that the storage does not take much space and can easily be transported. The results also indicate that the theoretical round trip efficiency of this technology is close to that of compressed hydrogen energy storage. 

    This study indicates that there is a theoretical potential for metal energy storage technology. However, the study was done purely theoretically in a best-case scenario meaning that future research, with a focus on the real-life applications of the technology, must be conducted to definitively prove if metals for energy storage is a viable option for future energy storage or not. 

    Ladda ner fulltext (pdf)
    fulltext
  • 41.
    Jonsson Dahl, Linus
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial.
    Modelling Creep and Crack Propagation in Ni-base Superalloy Joints for Improved Test Planning2023Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Siemens Energy in Finspång develop, manufacture and deliver gas turbines to all over the world. To ensure that alloys and designs can withstand the thermo-mechanical loads seen in a gas turbine, especially those in the hotter sections of the turbine stage, creep and crack initiation/propagation testing is performed. Structural joints, such as brazing joints, likely contain defects and have reduced crack propagation resistance compared to the base material bodies which they join. Siemens Energy are interested in spearheading the use of FEM- and crack propagation software such as FRANC3D to model and simulate crack growth in structural joints, to aid in planning and evaluating joint test results.

    In this project, a first attempt was made to model crack growth in Ni-base superalloy joints. The joints in question were brazing joints in IN792 with Amdry DF-4B as brazing filler metal. Two geometries were selected for this first attempt: A simple single edge notch specimen (SEN-FSP) and a Reference Case in the form of a creep fracture test specimen with a semi-conical brazing joint. Using the SEN-FSP specimen, joints under pure tensile- and mixed tensile-shear loading were modeled, simulated and compared. ABAQUS was used to perform a shakedown analysis in the SEN-FSP specimen joints, creating a stable and mostly elastic state ready for use with LEFM based FRANC3D. In FRANC3D, a penny shaped crack was introduced for both specimens. For the creep fracture test Reference Case, an approach to modelling concurrent large scale creep and crack propagation was tested for a number of scenarios, involving different degrees of initial stress redistribution. Due to inability to apply separate joint- and base material crack propagation properties in FRANC3D, and a lack of joint property data, the model had to be based on a large number of assumptions.

    From results generated by the SEN-FSP- and Reference Case models, the potential is clear, but for such models to leave the pilot stage and transition to being tools capable of generating usable numerical results, improved joint modelling possibilities in FRANC3D combined with ’simulation friendly’ testing for joint properties is necessary.

  • 42.
    Cui, Luqing
    et al.
    Xi An Jiao Tong Univ, Peoples R China.
    Deng, Dunyong
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Jiang, Shuang
    Northeastern Univ, Peoples R China.
    Peng, Ru
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Xin, Tongzheng
    Univ Hong Kong, Peoples R China.
    Zhang, Honghong
    Xi An Jiao Tong Univ, Peoples R China.
    Hegedues, Zoltan
    Univ Hong Kong, Peoples R China; Deutsch Elektronen Synchrotron DESY, Germany.
    Lienert, Ulrich
    Deutsch Elektronen Synchrotron DESY, Germany.
    He, Weifeng
    Xi An Jiao Tong Univ, Peoples R China.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    New insights into the anisotropic ductility of additively manufactured Inconel 7182023Ingår i: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 169, artikel-id 103738Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anisotropic ductility in additively manufactured (AM) alloys, namely better ductility along the building direction (BD) has been extensively studied and traditionally attributed to the crystallographic texture. However, recent studies have shown significant ductility anisotropy in weakly or non-textured AM alloys, indicating that other factors may also play critical roles. To explore this, AM Inconel 718 with weak crystallographic texture was selected as the model material, and the in-situ high-energy X-ray diffraction tests together with multiscale microstructural characterization techniques were performed to explore the deformation micromechanisms. The results of this study, for the first time, revealed that the better ductility in the vertical specimen (loading parallel to BD) was partially due to the negative stress triaxiality factor (TF) of the {220} grains during plastic deformation, which results in the shrinkage or even healing of the microvoids. Furthermore, the & delta;-phase alignment in conjunction with grain boundary orientation were also proved to have a pronounced impact on the anisotropic ductility of AM alloys. On the other hand, though in the overall weak-textured microstructure, the proportion of 101 grains were marginally over other grains. Thus, the positive effect of {220} grains on ductility was stronger than the negative effect of {200} and {311} grains, contributing to the excellent failure elongation exceeding 12% for both samples. The findings of this study shed new light on the mechanisms underlying the anisotropic ductility of AM alloys and provide insight into strategies for enhancing their performance.

  • 43.
    Azeez, Ahmed
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Leidermark, Daniel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Segersäll, Mikael
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Numerical prediction of warm pre-stressing effects for a steam turbine steel2023Ingår i: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638, Vol. 125, artikel-id 103940Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In warm pre-stressing (WPS), the fracture resistance of cracked steel components is raised when subjected to certain temperature-load histories. WPS’s beneficial effects enhance safety margins and potentially prolong fatigue life. However, understanding and predicting the WPS effects is crucial for employing such benefits. This study utilised pre-cracked compact tension specimens made from steam turbine steel for WPS and baseline fracture toughness testing. Two typical WPS cycles were investigated (L-C-F and L-U-C-F), and an increase in fracture resistance was observed for both cycles. The WPS tests were simulated using finite element analysis to understand its effects and predict the increase in fracture resistance. A local approach was followed based on accumulative plastic strain magnitude ahead of the crack tip. Since cleavage fracture is triggered by active plasticity, the WPS fracture is assumed when accumulated plasticity exceeds the residual plastic zone formed at the crack tip due to the initial pre-load.

    Ladda ner fulltext (pdf)
    fulltext
  • 44.
    Yang, H.
    et al.
    Jiamusi Univ, Peoples R China.
    Wang, N.
    Jiamusi Univ, Peoples R China.
    Wang, Y. D.
    Univ Sci & Technol Beijing, Peoples R China.
    Peng, Ru Lin
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Li, S. L.
    Univ Sci & Technol Beijing, Peoples R China.
    Origin of quasi-linear superelasticity at high temperature in Ni-Mn-Ga-Co shape memory alloy2023Ingår i: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 162, artikel-id 108001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The quasi-linear superelasticity in Ni-Mn-Ga-Co shape memory alloy displays a complete recoverable strain of similar to 3% at 473 K for the cubic phase in precursor state. The in-situ neutron diffraction experiments provide the direct evidence on the stress-induced transition from the precursor state to martensite via the continuous variation of lattice parameter and peak width under uniaxial stress field. The anomalous broadening in peak width suggests that the external stress field may trigger very high heterogeneity in lattice distortion for the initial precursor state having randomly-distributed domains with short-range strain ordering prior to the martensitic transformation. The origin of the quasi-linear superelasticity at high temperature is considered as the ruggedness of the local energy landscape. The present investigations provide new insight into the understanding of superelasticity in shape memory alloys.

  • 45. Beställ onlineKöp publikationen >>
    Sun, Xiaoyu
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Performance of High-temperature Coatings: Oxidation and Interdiffusion2023Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The use of aluminiferous coatings profoundly improves the service life of superalloys but leads to the microstructural degradation of superalloys and thus the loss of mechanical properties. To solve this trade-off, two strategies were employed in this research.

    At first, we modified MCrAlY coatings by inducing Ta to reduce the interdiffusion effect on substrate alloys. This strategy was verified by 2000 h/1100 °C oxidation tests in two Ta-containing MCrAlY-IN792 systems. The system with 3.3 wt.% Ta MCrAlY displays an outstanding resistance to γ′ depletion in the substrate and comparable oxidation property in comparison with a reference system of Ta-free MCrAlY-IN792. Increasing Ta to 7.4 wt.% results in reduced oxidation resistance. Thermodynamic simulations revealed the phase-transformation mechanism induced by initial interdiffusion, uncovering the cause of γ′ depletion in the substrate and the mechanism behind improving resistance to γ′ depletion by Ta addition.

    In addition, we developed novel Y-doped AlCoCrFeNi high-entropy alloys by tuning Al/Cr ratio ACR. After a long-term isothermal test in air at 1100 °C up to 1000 h, the higher ACR alloy displayed a stronger oxidation resistance at the early oxidation stage, whereas a contrary result could be detected in the later stage. The microstructural analysis confirmed that the fast growth of spinel dominated the early oxidation process, leading to higher oxidation rate of the lower ACR alloys. The later stage was governed by the growth of Al2O3. Lager size Al2O3 gain formed on the lower ACR alloy impeded the inward diffusion of oxygen and thus reduced the oxidation rate, which was further verified by our thermodynamic calculations.

    Delarbeten
    1. Impeding the γ' depletion during the interdiffusion between bond coatings and superalloys via introduction of tantalum in bond coatings
    Öppna denna publikation i ny flik eller fönster >>Impeding the γ' depletion during the interdiffusion between bond coatings and superalloys via introduction of tantalum in bond coatings
    Visa övriga...
    2023 (Engelska)Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 227, artikel-id 111792Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The use of aluminiferous coatings profoundly improves the service life of superalloys but leads to microstructural degradation of superalloys and thus loss of mechanical properties. In this study, we mod- ified MCrAlY coatings by adding Ta to reduce the interdiffusion effect on substrate alloys. This strategy was verified by 2000 h/1100 °C oxidation tests in two Ta-containing MCrAlY-IN792 systems. The system with 3.3 wt% Ta MCrAlY exhibits an outstanding resistance to c0 depletion in the substrate and compa- rable oxidation property in comparison with a reference system of Ta-free MCrAlY-IN792. Increasing Ta to 7.4 wt% results in reduced oxidation resistance. Thermodynamic simulations revealed the phase- transformation mechanism induced by initial interdiffusion, uncovering the cause of c0 depletion in the substrate and the mechanism behind improving resistance to c0 depletion by Ta addition.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2023
    Nyckelord
    Bonding coating; Interdiffusion; Microstructural degradation; Thermodynamics
    Nationell ämneskategori
    Bearbetnings-, yt- och fogningsteknik Metallurgi och metalliska material
    Identifikatorer
    urn:nbn:se:liu:diva-192738 (URN)10.1016/j.matdes.2023.111792 (DOI)000991285600001 ()2-s2.0-85149289646 (Scopus ID)
    Projekt
    High entropy alloy coatings for green hydrogen gas turbines
    Forskningsfinansiär
    International Interdisciplinary Materials Science Laboratory for Advanced Functional Materials (AFM)
    Anmärkning

    Funding: Siemens Industrial Turbomachinery AB (Finspang, Sweden); Swedish Energy Agency through KME; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University [SFO-Mat-LiU 2009-00971]

    Tillgänglig från: 2023-03-28 Skapad: 2023-03-28 Senast uppdaterad: 2024-02-27Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner (png)
    presentationsbild
  • 46.
    Ahlqvist, Max
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. Epiroc Rock Drills AB, Sweden.
    Weddfelt, Kenneth
    Epiroc Rock Drills AB, Sweden.
    Norman, Viktor
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Leidermark, Daniel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Probabilistic evaluation of the Step-Stress fatigue testing method considering cumulative damage2023Ingår i: Probabilistic Engineering Mechanics, ISSN 0266-8920, E-ISSN 1878-4275, Vol. 74, artikel-id 103535Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A general testing and analysis framework for the Step-Stress fatigue testing method is identified, utilizing interval-censored data and maximum likelihood estimation in an effort to improve estimation of fatigue strength distribution parameters has been performed. The Step-Stress methods limitations are characterized, using a simple material model that considers cumulative damage to evaluate load history effects. In this way, the performance including cumulative damage was evaluated and quantified using a probabilistic approach with Monte-Carlo simulations, benchmarked against the Staircase method throughout the work. It was found that the Step-Stress method, even when cumulative damage occurs to a wide extent, outperforms the Staircase method, especially for small sample sizes. Furthermore, positive results reaches further than the increase performance in estimating fatigue strength distribution parameters, where improvements in secondary information, i.e. S-N data gained from failure specimens, are shown to be distributed more closely to the fatigue life region of interest.

    Ladda ner fulltext (pdf)
    fulltext
  • 47.
    Ljusell, Ida
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial.
    Process characterisation of an additive manufacturing equipment: An analysis of the effect of electron beam powder bed fusion process parameters on the melt pool geometry and microstructure of Ti-6Al-4V2023Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Additive manufacturing (AM) are manufacturing methods where components are produced by adding material layer by layer which allows for a high freedom of design as well as little or no material waste compared to conventional manufacturing methods. Despite the many benefits of AM there are still problems concerning the quality of the produced material. In this project an AM equipment was tested by using different process parameters and comparing their effect on the printed material. An electron beam powder bed fusion equipment was used and with varying values for beam power, scanning speed and preheat temperature. Initial tests were done using Ti-6Al-4V plates with a Ti-6Al-4V powder then being used for a few selected process settings. The EB-PBF did not act as predicted with varying beam powers compared to input values. Melting tracks using powder also proved to be difficult due to, for example, the build plate moving from being overcharged by the electron beam and the difficulty to control the powder layers. The geometry of printed tracks on plates was analysed and values for melt pool width, depth and height was measured. Both width and depth for the most part have a linear increase with increased power and line energy density. Preheating temperature has a smaller effect on the width and depth but leads to more even tracks.

    Ladda ner fulltext (pdf)
    Process characterisation of anadditive manufacturing equipment
  • 48.
    Romanov, Pavel
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. University of Gävle, Sweden.
    Jahedi, Mohammad
    University of Gävle, Sweden.
    Petersson, Anders
    Väderstad Components AB, Överum, Sweden.
    Moshfegh, Bahram
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Energisystem. Linköpings universitet, Tekniska fakulteten. University of Gävle, Sweden.
    Calmunger, Mattias
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. University of Gävle, Sweden.
    Quenching of Carbon Steel Plates with Water Impinging Jets: Differential Properties and Fractography2023Ingår i: Procedia Structural Integrity, ISSN 2452-3216, Vol. 43, s. 154-159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The demand for steel components with tailored properties is constantly growing. To obtain a specific variation of microstructures and mechanical properties along the component it must undergo a controllable cooling. One way to control the cooling rates along the component is by using different simultaneous water jet impingements on a hot austenitized surface. This can be done by a newly developed test rig for water Impinging Jet Quenching Technique (IJQT). This work discusses the effect of IJQT on mechanical properties and fracture behavior of 15 mm steel plates containing 0.27 and 0.38 mass-% carbon. The samples were cooled in a specifically designed setup of the technique to obtain simultaneous water and air cooling resulting in diverse microstructures. The mechanical property gradients of both steels were analyzed through hardness measurements and tensile tests. The fracture surfaces and the near fracture regions were observed using scanning electron microscope and light optical microscope respectively. The results from tensile tests showed that the larger part of the sample with higher carbon content was fully hardened, however smoothly transitioning to a more ductile region. The sample with lower carbon content combined various degrees of hardening and transitioned from higher to lower ultimate tensile strength values. Fracture behavior of higher carbon steel was predominantly brittle transitioning to a ductile, while the lower carbon steel had a small region showing brittle fracture transitioning to a larger region of predominant ductile fracture behavior.

    Ladda ner fulltext (pdf)
    fulltext
  • 49.
    Chai, Guocai
    et al.
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Sandvik Mat Technol, Sweden.
    Siriki, Raveendra
    Sandvik Mat Technol, Sweden.
    Nordström, Joakim
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten. Sandvik Mat Technol, Sweden.
    Dong, Zhihua
    KTH, Sweden; Chongqing Univ, Peoples R China.
    Vitos, Levente
    KTH, Sweden.
    Roles of Nitrogen on TWIP in Advanced Austenitic Stainless Steels2023Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 94, nr 10, artikel-id 2200359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of nitrogen on the mechanical properties of two high Ni containing advanced austenitic stainless steels with low stacking fault energies is investigated. The results show that increase of nitrogen content greatly increases both strength and elongation of the steel at the same time. At the cryogenic temperature, the steels show a twin induced plasticity behavior. Ab initio calculations indicate that the increase of nitrogen slightly increases the stacking fault energy and consequently the critical shear stress for twin initiation in the steel. However, addition of nitrogen significantly increases the flow stress. This leads to a smaller critical strain for twin initiation and promotes deformation twinning in the high nitrogen steel. This is confirmed by the microstructure investigation. Deformation in steels is a competitive process between slip and twinning. Dislocation slip is dominant at low strain range, but formation of stacking fault and twinning become important in the later stages of deformation. At cryogenic temperature, it is mainly deformation twinning. The influence of nitrogen addition on magnetic property and its effect on deformation twinning are also discussed. The present study increases the understanding for the development of high-performance and low-cost advanced austenitic stainless steels.

    Ladda ner fulltext (pdf)
    fulltext
  • 50.
    Lindstrom, Stefan B.
    et al.
    Mid Sweden Univ, Sweden.
    Moverare, Johan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Xu, Jinghao
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Konstruktionsmaterial. Linköpings universitet, Tekniska fakulteten.
    Leidermark, Daniel
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Robert
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten.
    Ansell, Hans
    Saab AB, S-58188 Linkoping, Sweden.
    Kapidzic, Zlatan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanik och hållfasthetslära. Linköpings universitet, Tekniska fakulteten. Saab AB, S-58188 Linkoping, Sweden.
    Service-life assessment of aircraft integral structures based on incremental fatigue damage modeling2023Ingår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 172, artikel-id 107600Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Ottosen-Stenstrom-Ristinmaa (OSR) incremental fatigue damage model is adapted for fatigue-life as-sessment of integral airframes milled from 7050-T7451 aluminum plates. For validation, variable-amplitude high-cycle fatigue experiments are conducted for circumferentially notched, axisymmetric specimens, and for a geometry similar to an aircraft fuselage frame, with flanges, stiffeners, and web panels. We also describe how the parameters of the OSR model can be modified to account for surface roughness, and for setting acceptable failure probability.

    Ladda ner fulltext (pdf)
    fulltext
1234567 1 - 50 av 587
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf