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Chai, Guocai
Publications (10 of 62) Show all publications
Wärner, H., Calmunger, M., Chai, G., Johansson, S. & Moverare, J. (2019). Thermomechanical Fatigue Behaviour of Aged Heat Resistant Austenitic Alloys. International Journal of Fatigue (127), 509-521
Open this publication in new window or tab >>Thermomechanical Fatigue Behaviour of Aged Heat Resistant Austenitic Alloys
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2019 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, no 127, p. 509-521Article in journal (Refereed) Published
Abstract [en]

The increasing demands for efficiency and flexibility result in more severe operating conditions for the materials used in critical components of biomass power plants. These operating conditions involve higher temperature ranges, more pronounced environmental effects and cyclic operations. Austenitic stainless steels have shown to possess promising high temperature properties which makes them suitable as candidates for critical components in biomass power plant. However, their behaviour under such conditions is not yet fully understood. This work investigates three commercial austenitic alloys: Esshete 1250, Sanicro 25 and Sanicro 31HT. The alloys were subjected to in-phase (IP) thermomechanical fatigue (TMF) testing under strain-control in the temperature range of 100–800 °C. Both virgin and pre-aged TMF specimens were tested in order to simulate service degradation resulting from long-term usage. The results show that the pre-aged specimens suffered shorter TMF-life compared to the virgin specimens. The scanning electron microscopy methods electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) were used to analyse and discuss active failure and deformation mechanisms. The difference in TMF-life produced by the two testing conditions was attributed to an embrittling effect by precipitation, reduced creep properties and oxidation assisted cracking.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Thermomechanical fatigue, austenitic alloys, pre-ageing
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-159644 (URN)10.1016/j.ijfatigue.2019.06.012 (DOI)2-s2.0-85068255817 (Scopus ID)
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-20Bibliographically approved
Wärner, H., Calmunger, M., Chai, G. & Moverare, J. (2018). Creep-Fatigue Interaction in Heat Resistant Austenitic Alloys. In: EDP Sciences (Ed.), MATEC Web of Conferences 165 , 05001 (2018): . Paper presented at Fatigue 2018 , 12th International Fatigue Congress, 27 May-1 June 2018, Poitiers, France. EDP Sciences, 165
Open this publication in new window or tab >>Creep-Fatigue Interaction in Heat Resistant Austenitic Alloys
2018 (English)In: MATEC Web of Conferences 165 , 05001 (2018) / [ed] EDP Sciences, EDP Sciences, 2018, Vol. 165Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
EDP Sciences, 2018
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-148182 (URN)10.1051/matecconf/2018165505001 (DOI)
Conference
Fatigue 2018 , 12th International Fatigue Congress, 27 May-1 June 2018, Poitiers, France
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-11-27
Calmunger, M., Chai, G., Eriksson, R., Johansson, S. & Moverare, J. J. (2017). Characterization of austenitic stainless steels deformed at elevated temperature. Metallurgical and Materials Transactions. A, 48A(10), 4525-4538
Open this publication in new window or tab >>Characterization of austenitic stainless steels deformed at elevated temperature
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2017 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 10, p. 4525-4538Article in journal (Refereed) Published
Abstract [en]

Highly alloyed austenitic stainless steels are promising candidates to replace more expansive nickel-based alloys within the energy-producing industry. The present study investigates the deformation mechanisms by microstructural characterisation, mechanical properties and stress-strain response of three commercial austenitic stainless steels and two commercial nickel-based alloys using uniaxial tensile tests at elevated temperatures from 400 C up to 700 C. The materials showed different influence of temperature on ductility, where the ductility at elevated temperatures increased with increasing nickel and solid solution hardening element content. The investigated materials showed planar dislocation driven deformation at elevated temperature. Scanning electron microscopy showed that deformation twins were an active deformation mechanism in austenitic stainless steels during tensile deformation at elevated temperatures up to 700 C.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2017
Keywords
Austenitic stainless steel, Nickel-based alloy, Microstructural characterization, Deformation twinning, Stress-strain response
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-122942 (URN)10.1007/s11661-017-4212-9 (DOI)000408884300012 ()
Note

Previous status of this publication was manuscript

Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish National Energy Administration through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]; AFM Strategic Faculty Grant SFO-MAT-LiU at Linkoping University [2009-00971]

Available from: 2015-11-30 Created: 2015-11-30 Last updated: 2017-09-22Bibliographically approved
Calmunger, M., Eriksson, R., Chai, G., Johansson, S. & Moverare, J. (2017). Influence of Cyclic Oxidation in Moist Air on Surface Oxidation-Affected Zones. In: : . Paper presented at EUROMAT17, Thessaloniki 17-21 September 2017,Greece (pp. 1-1).
Open this publication in new window or tab >>Influence of Cyclic Oxidation in Moist Air on Surface Oxidation-Affected Zones
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2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-143972 (URN)
Conference
EUROMAT17, Thessaloniki 17-21 September 2017,Greece
Available from: 2018-01-01 Created: 2018-01-01 Last updated: 2018-01-16Bibliographically approved
Calmunger, M., Eriksson, R., Chai, G., Johansson, S., Högberg, J. & Moverare, J. (2017). Local Surface Phase Stability During Cyclic Oxidation Process. Paper presented at THERMEC'16, May 30 - June 3, 2016, Graz, Austria. Materials Science Forum, 879, 855-860
Open this publication in new window or tab >>Local Surface Phase Stability During Cyclic Oxidation Process
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2017 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 879, p. 855-860Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Trans Tech Publications, 2017
Keywords
Austenitic stainless steels, thermal cycling, corrosion, surface phase stability
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-129244 (URN)10.4028/www.scientific.net/MSF.879.855 (DOI)
Conference
THERMEC'16, May 30 - June 3, 2016, Graz, Austria
Available from: 2016-06-14 Created: 2016-06-14 Last updated: 2017-11-28
Wärner, H., Calmunger, M., Chai, G., Johansson, S. & Moverare, J. (2017). Thermomechanical Fatigue Behavior of Aged Heat Resistant Austenitic Alloys. In: : . Paper presented at EUROMAT17, Thessaloniki 17-21 September 2017,Greece (pp. 1-1).
Open this publication in new window or tab >>Thermomechanical Fatigue Behavior of Aged Heat Resistant Austenitic Alloys
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2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-143978 (URN)
Conference
EUROMAT17, Thessaloniki 17-21 September 2017,Greece
Available from: 2018-01-01 Created: 2018-01-01 Last updated: 2018-01-16Bibliographically approved
Chai, G. (2016). Analysis of microdamage in a nickel-base alloy during very high cycle fatigue. Fatigue & Fracture of Engineering Materials & Structures, 39(6), 712-721
Open this publication in new window or tab >>Analysis of microdamage in a nickel-base alloy during very high cycle fatigue
2016 (English)In: Fatigue & Fracture of Engineering Materials & Structures, ISSN 8756-758X, E-ISSN 1460-2695, Vol. 39, no 6, p. 712-721Article in journal (Refereed) Published
Abstract [en]

Fatigue damage in a metallic material during very high cycle fatigue can strongly be correlated to the microstructure. This paper provides a review and a discussion on the micro damage behaviours in a nickel-base alloy during very high cycle fatigue using microplasticity and material mechanics. The results show that cyclic plastic deformation in this material can occur very locally even with an applied stress that is much lower than the yield strength. The fatigue damage occurs mainly at grain or twin boundaries because of local impingement and interaction of slip bands and these boundaries. The crystallographic properties, Schmid factors and orientations of grain and boundaries play very important roles to the fatigue damage. Subsurface fatigue crack initiation in the matrix is one of very high cycle fatigue mechanisms. Twinning and detwinning can also occur during the very high cycle fatigue process.

Place, publisher, year, edition, pages
WILEY-BLACKWELL, 2016
Keywords
dislocation; grain boundary; misorientation; Schmid factor; twin and detwin; very high cycle fatigue
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-128717 (URN)10.1111/ffe.12412 (DOI)000375046100006 ()
Available from: 2016-06-07 Created: 2016-05-30 Last updated: 2017-11-30
Calmunger, M., Chai, G., Johansson, S. & Moverare, J. (2016). Creep and Fatigue Interaction Behavior in Sanicro 25 Heat Resistant Austenitic Stainless Steel. Paper presented at 7th International Conference on Creep, 19-22 January 2016, IGCAR, Kalpakkam, India. Transactions of the Indian Institute of Metals, 69(2), 337-342
Open this publication in new window or tab >>Creep and Fatigue Interaction Behavior in Sanicro 25 Heat Resistant Austenitic Stainless Steel
2016 (English)In: Transactions of the Indian Institute of Metals, ISSN 0972-2815, E-ISSN 0975-1645, Vol. 69, no 2, p. 337-342Article in journal (Refereed) Published
Abstract [en]

Sanicro 25 is a newly developed advanced high strength heat resistant austenitic stainless steel. The material shows good resistance to steam oxidation and flue gas corrosion, and has higher creep rupture strength than other austenitic stainless steels available today. It is thus an excellent candidate for superheaters and reheaters for advanced ultra-super critical power plants with efficiency higher than 50 %. This paper provides a study on the creep–fatigue interaction behavior of Sanicro 25 at 700 °C. Two strain ranges, 1 and 2 %, and two dwell times, 10 and 30 min, were used. The influences of dwell time on the cyclic deformation behavior and life has been evaluated. Due to stress relaxation the dwell time causes a larger plastic strain range compared to the tests without dwell time. The results also show that the dwell time leads to a shorter fatigue life for the lower strain range, but has no or small effect on the life for the higher strain range. Fracture investigations show that dwell times result in more intergranular cracking. With the use of the electron channeling contrast imaging technique, the influences of dwell time on the cyclic plastic deformation, precipitation behavior, recovery phenomena and local plasticity exhaustion have also been studied.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
Sanicro 25, advanced ultra-super critical power plant, creep, low cycle fatigue, cyclic plastic deformation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:liu:diva-123646 (URN)10.1007/s12666-015-0806-3 (DOI)000368032700027 ()
Conference
7th International Conference on Creep, 19-22 January 2016, IGCAR, Kalpakkam, India
Note

At the time for thesis presentation publication was in status: Manuscript

Funding agencies: AB Sandvik Materials Technology in Sweden; Swedish National Energy Administration through the Research Consortium of Materials Technology for Thermal Energy Processes [KME-701]; AFM Strategic Faculty Grant SFO-MAT-LiU at Linkoping University [2009-00971]

Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2017-12-01
Kangas, P. & Chai, G. (2016). Duplex Stainless Steels for Oil & Gas Applications. In: : . Paper presented at The 17th Asian Pacific Corrosion Control Conference, January 27-30, 2016, IIT Bombay, Mumbai, India (pp. 1-12).
Open this publication in new window or tab >>Duplex Stainless Steels for Oil & Gas Applications
2016 (English)Conference paper, Published paper (Refereed)
Keywords
duplex stainless steels, corrosion resistance, mechanical property, oil & gas industry
National Category
Materials Engineering
Identifiers
urn:nbn:se:liu:diva-123647 (URN)
Conference
The 17th Asian Pacific Corrosion Control Conference, January 27-30, 2016, IIT Bombay, Mumbai, India
Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2016-01-12
Polák, J., Petrás, R., Heczko, M., Kruml, T. & Chai, G. (2016). Evolution of the Cyclic Plastic Response of Sanicro 25 Steel Cycled at Ambient and Elevated Temperatures. International Journal of Fatigue, 83(1), 75-83
Open this publication in new window or tab >>Evolution of the Cyclic Plastic Response of Sanicro 25 Steel Cycled at Ambient and Elevated Temperatures
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2016 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 83, no 1, p. 75-83Article in journal (Refereed) Published
Abstract [en]

Cyclic plastic response of the austenitic heat resistant steel Sanicro 25 has been studied during strain controlled low cycle fatigue tests performed at ambient and at elevated temperature. Simultaneously with the cyclic hardening/softening curves hysteresis loops during cyclic loading were analyzed using generalized statistical theory of the hysteresis loop. The probability density distribution function of the internal critical stresses, the effective saturated stress and their evolution during cycling were derived for various strain amplitudes. The internal dislocation structure and the surface relief at room and at elevated temperature were studied and correlated with the cyclic stress–strain response and the evolution of the probability density function of the internal critical stresses.

Keywords
cyclic plasticity, hysteresis loop analysis, heat resistant steel, dislocation structure, effect of temperature
National Category
Other Materials Engineering Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-123644 (URN)10.1016/j.ijfatigue.2015.03.015 (DOI)000367111200010 ()
Note

Funding agencies; GACR [13-23652S]; European Regional Development Fund [CZ.1.05/1.1.00/02.0068];  [RVO: 68081723]

Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2017-12-01
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