liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Residual stresses, fatigue and deformation in cast iron
Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The complex geometry of cylinder heads in heavy-duty diesel engines makes grey iron or compact graphite iron a preferred material choice due to its price, castability, thermal conductivity and damping capacity. Today’s strict emission laws have increased the demands on engine performance and engine efficiency. This means that material properties such as fatigue resistance need to be improved. Shot peening is often used to improve the fatigue resistance of components and the benefits of shot peening are associated with the induced compressive surface stresses and surface hardening. How different shot peening parameters can affect fatigue strength of grey and compact graphite iron has been investigated within the project underlying this thesis. To do this, X-ray diffraction (XRD) was utilized for residual stress measurements, scanning electron microscopy (SEM) for microstructural characterizations and mechanical fatigue testing for mechanical quantifications. The ultimate aim of this work has been to increase the fatigue resistance of cast iron by residual stress optimization.

XRD measurements and SEM examinations revealed that the shot peening parameters shot size and peening intensity significantly influence residual stresses and surface deformation. Residual stress profiles, similar to the one general considered to improve the fatigue strength in steels, were obtained for both grey and compact graphite iron. Uniaxial push-pull fatigue testing on grey iron with these shot peening parameters reduced the fatigue strength with 15–20 %. The negative effect is likely related to surface damage associated with over peening and relatively high subsurface tensile residual stresses. With very gentle shot peening parameters, the uniaxial fatigue strength were unaltered from the base material but when subjected to bending fatigue an increase in fatigue strength were observed. An alternative way to increase the fatigue strength was to conduct a 30 min annealing heat treatment at 285 XC which increased the fatigue strength by almost 10 % in uniaxial loading. The improvement could be an effect of favourable precipitates forming during the annealing, which could hinder dislocation movement during fatigue.

Measuring residual stresses using XRD and the sin2 -method demands accurate X-ray elastic constants (XEC) for meticulous stress analysis. The XEC referred to as 1~2s2 should therefore always be calibrated for the specific material used. The experiments conducted revealed that the XEC value is independent of the testing method used in this work. A small correction from the theoretical value should be applied when the material contains small amounts of residual stresses. The amount of residual stresses has a great impact on the XEC and thus on the stress analysis. Concluding that proper analysis of residual stresses in cast iron is not straight forward.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. , p. 44
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1908
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:liu:diva-150783DOI: 10.3384/diss.diva-150783ISBN: 9789176853580 (print)OAI: oai:DiVA.org:liu-150783DiVA, id: diva2:1243234
Public defence
2018-09-28, ACAS, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2018-08-30 Created: 2018-08-30 Last updated: 2018-09-21Bibliographically approved
List of papers
1. In-situ SEM/EBSD Study of Deformation adn Fracture Behaviour of Flake Cast Iron
Open this publication in new window or tab >>In-situ SEM/EBSD Study of Deformation adn Fracture Behaviour of Flake Cast Iron
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Cast irons’ position as an important engineering material is un-disputed. They are widely used in many important industrial applications such as the automotives and workshop machinery. Nevertheless, fracture mechanisms in cast irons are not fully understood. In this study the fracture path and non-linear elastic behaviour of a fully pearlitic flake cast iron under uniaxial tensile loading have been investigated in a Scanning Electron Microscope (SEM) equipped with an Electron Backscattering Diffraction (EBSD) detector. The tensile load was applied via a specially made sample stage. Under uniaxial tensile loading the graphite flakes act as notches or cracks and therefore the fracture process starts at one or many graphite tips. The crack can propagate in many different ways, at the graphite and matrix interface, through the graphite, at the interface between cementite and ferrite or through the pearlitic grains. At the point where the stress strain curve deviates from its linear path plastic deformation at graphite tips can be noticed. Interface cracking between graphite and the matrix also starts at this point.

Keywords
high-temperature, ageing, toughness, austenitic stainless steel, nickel base alloy
National Category
Engineering and Technology Materials Engineering
Identifiers
urn:nbn:se:liu:diva-95430 (URN)
Conference
13th International Conference on Fracture ICF13, June 16-21, Beijing, China.
Available from: 2013-07-03 Created: 2013-07-03 Last updated: 2018-08-30
2. Fatigue Strength of Shot Peened Compacted Graphite Iron
Open this publication in new window or tab >>Fatigue Strength of Shot Peened Compacted Graphite Iron
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Keywords
compacted graphite iron, shot peening, fatigue, residual stress
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-109606 (URN)
Conference
12th International Conference on Shot Peening, 15-18 September 2014, Goslar, Germany
Available from: 2014-08-21 Created: 2014-08-21 Last updated: 2018-08-30
3. Influence of Shot Peening Parameters on Residual Stresses in Flake and Vermicular Cast Irons
Open this publication in new window or tab >>Influence of Shot Peening Parameters on Residual Stresses in Flake and Vermicular Cast Irons
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Test samples of grey and compacted graphite cast irons with pearlitic matrix were shot-peened to different surface conditions using twelve different combinations of shot size, peening intensity and peening coverage percentage. Relatively high surface compressive residual stresses varying between 245 to 565 MPa were observed and the compressive residual stresses reached a depth between 280 µm and 770 µm. Within the range of peening parameters used, the compacted graphite cast iron with its vermicular graphite showed a somewhat better response to the same shot-peening treatment than the grey cast iron containing flake graphite, giving a larger peening affected zone with higher compressive residual stresses. For both the cast irons, an increase in peening coverage percentage, shot size or peening intensity led often to a lower surface compressive stress. However, peening using a higher intensity greatly increased the degree and extent of plastic deformation and therefore increased the magnitude and penetration depth of the subsurface compressive residual stresses, while the effect of increasing shot size also depends on the peening intensity. On the other hand, measurements on the grey cast iron samples showed that the peening coverage has little effect on the depth profile of residual stress.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
National Category
Engineering and Technology Materials Engineering
Identifiers
urn:nbn:se:liu:diva-89578 (URN)10.4028/www.scientific.net/MSF.768-769.534 (DOI)000336693000070 ()
Conference
International Conference on Residual Stresses 9 (ICRS 9), Garmisch-Partenkirchen, Germany, 7 – 9 October 2012
Available from: 2013-03-13 Created: 2013-02-27 Last updated: 2018-08-30Bibliographically approved
4. Graphite Morphology's Influence on Shot Peening Results in Cast Irons
Open this publication in new window or tab >>Graphite Morphology's Influence on Shot Peening Results in Cast Irons
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The different shot peening responds of a grey cast iron (GI) with its flake graphite and a compacted cast iron (CGI) with its vermicular graphite was analyzed and compared in this paper. For peening using identical parameters, CGI showed a larger plastic deformation zone with higher subsurface compressive stresses than GI. Electron backscatter diffraction (EBSD) mapping and backscatter electron imaging revealed that plastic deformation of the matrix near graphite inclusions is affected by the size and geometry of the graphite. The different behaviors of graphite are explained by their capability to damp mechanical force but at the same time to cause stress concentration in the matrix. The better shot peening results for CGI may be attributed to a lower damping effect of its graphite inclusions and capability of the matrix for larger plastic deformation.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2014
Keywords
shot peening, cast iron, graphite morphology, EBSD, residual stress
National Category
Engineering and Technology Materials Engineering
Identifiers
urn:nbn:se:liu:diva-89582 (URN)10.4028/www.scientific.net/MSF.768-769.542 (DOI)000336693000071 ()
Conference
International Conference on Residual Stresses 9 (ICRS 9), Garmisch-Partenkirchen, Germany, 7 – 9 October 2012
Available from: 2013-03-13 Created: 2013-02-27 Last updated: 2018-08-30Bibliographically approved
5. Residual Stresses in Shot Peened Grey and Compact Iron
Open this publication in new window or tab >>Residual Stresses in Shot Peened Grey and Compact Iron
Show others...
2014 (English)In: HTM Journal of Heat Treatment and Materials, ISSN 1867-2493, Vol. 69, no 1, p. 38-45Article in journal (Refereed) Published
Abstract [en]

Grey cast iron and compacted graphite iron with a pearlitic matrix are investigated in this study after shot peening using twelve unique combinations of parameters, namely shot size, peening intensity and coverage, followed by residual stress measurements and evaluations. Cylindrical test samples were cut out from heavy truck cylinder heads and polished on the top flat surface to decrease effects from cutting. Residual stresses and the affected depth from the different peening conditions varied between −245 MPa to −565 MPa and from 280 μm to 770 μm in depth. Resultant surface compressive stresses decrease with increasing shot size, peening intensity or coverage whereas the affected depth increases with increasing intensity. The increased affected depth is a result from the increased extent and magnitude of plastic deformation. The compacted graphite iron was more affected by shot peening than the grey cast iron, meaning that the same shot peening parameters resulted in both higher compressive stresses and larger deformation depth.

Place, publisher, year, edition, pages
Carl Hanser Verlag GmbH, 2014
Keywords
Residual stress, FWHM, cast iron, shot peening, X-ray diffraction
National Category
Engineering and Technology Materials Engineering
Identifiers
urn:nbn:se:liu:diva-105158 (URN)10.3139/105.110207 (DOI)2-s2.0-84896531682 (Scopus ID)
Conference
International Conference on Residual Stresses ICRS9, October 7-9,2012 in Garmisch-Partenkirchen, Germany
Note

Enhanced contribution based upon a presentation at the International Conference on Residual Stresses ICRS9, October 7–9, 2012, in Garmisch-Partenkirchen, Germany

Available from: 2014-03-10 Created: 2014-03-10 Last updated: 2018-08-30Bibliographically approved
6. Shot Peening Induced Plastic Deformation in Cast Iron - Influence of Graphite Morphology
Open this publication in new window or tab >>Shot Peening Induced Plastic Deformation in Cast Iron - Influence of Graphite Morphology
Show others...
2014 (English)In: HTM Journal of Heat Treatment and Material, ISSN 1867-2493, Vol. 69, no 2, p. 106-113Article in journal (Refereed) Published
Abstract [en]

Graphite morphology in cast iron strongly affects the mechanical properties such as: Young's modulus, tensile/compressive strength and cyclic mechanical behaviour. In this study, pearlitic compact graphite iron (CGI) and grey cast iron (GI) have been studied in a scanning electron microscope (SEM) before and after shot peening under different conditions. The plastic deformation behaviour of CGI and GI under different shot peening conditions has been analysed using electron backscattering diffraction (EBSD) and electron contrast channelling imaging (ECCI). EBSD and ECCI revealed that plastic deformation around graphite inclusions depends on the size and shape of the graphite. The different response of CGI and GI to shot peening is explained by the different damping properties of the graphite and the matrix capability for plastic deformation.

Place, publisher, year, edition, pages
München: Carl Hanser Verlag GmbH, 2014
Keywords
shot peening, cast iron, graphite morphology, EBSD, residual stress
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-106715 (URN)10.3139/105.110213 (DOI)
Conference
International Conference on Residual Stresses ICRS9, October 7-9, 2012, Garmisch-Partenkirchen, Germany
Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2018-08-30Bibliographically approved
7. Analysis of Residual Stress in Stres Harps of Grey Iron by Experiment and Simulation
Open this publication in new window or tab >>Analysis of Residual Stress in Stres Harps of Grey Iron by Experiment and Simulation
Show others...
2014 (English)Conference paper, Published paper (Refereed)
Keywords
residual stress, cast iron, FE simulation, neutron diffraction, hole drilling
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-108773 (URN)
Conference
9th European Conference on Residual Stresses ECRS-9, Troyes, France, 7-10 July 2014
Available from: 2014-07-04 Created: 2014-07-04 Last updated: 2018-08-30
8. Characterization of Hastelloy X Produced by Laser Powder Bed Additive Manufacturing
Open this publication in new window or tab >>Characterization of Hastelloy X Produced by Laser Powder Bed Additive Manufacturing
2016 (English)In: World PM2016 Proceedings, EPMA , 2016, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

The grain structure of the selective laser melting (SLM) material is complicated and cannot easily be resolved by etching of the as-manufactured surface. One method to reveal the true morphology is by performing an electron backscatter diffraction (EBSD) analysis of the material. An analysis of the SLM material is reported. The analysis reveals that the grain structure is very complicated and the grain size is non-uniform. The microstructure contains large grains with multiple low angle grain boundaries together with small grains that approach nanometre size in the smallest size range. Grains are to a large extent, not equiaxed, but rather elongated.

Varying degrees of texture in different regions of the material have been observed. The degree of texture coincides with material volumes manufactured with different process parameter settings. Also areas with and without indications of texture have shown to exhibit different hardness. This is an indication of variation in mechanical properties in the different material volumes. Thin-walled areas, surface regions of solid material and lattices constitutes one group with similar microstructure indicating one class of material and secondly the bulk material with another microstructure would constitute the other material class

Place, publisher, year, edition, pages
EPMA, 2016
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-132934 (URN)978-1-899072-48-4 (ISBN)
Conference
World PM2016 - Powder Metallurgy World Congress & exhibition, Hamburg, Germany, October 9-13, 2016
Available from: 2016-12-02 Created: 2016-12-02 Last updated: 2018-08-30Bibliographically approved

Open Access in DiVA

Residual stresses, fatigue and deformation in cast iron(6523 kB)252 downloads
File information
File name FULLTEXT01.pdfFile size 6523 kBChecksum SHA-512
86e1c33687e3609ae495533c98a55164301a429cfd9a1e14be9a1f2b6cc042621647c2d471e9dfde1198e492c4001f2730618ccb771bdc1e663e1e16fae8b4cd
Type fulltextMimetype application/pdf
omslag(530 kB)11 downloads
File information
File name COVER01.pdfFile size 530 kBChecksum SHA-512
f04b84f96bf27570f5d7830a7289367644112b9c4e31b6268592a1147de0672dd06d115b4f76f19ab9104cce70124a8d1e359409036f5d4dfc8fbf882d523e67
Type coverMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Lundberg, Mattias

Search in DiVA

By author/editor
Lundberg, Mattias
By organisation
Engineering MaterialsFaculty of Science & Engineering
Other Materials Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 252 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 344 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf