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Persistent URL http://purl.org/net/epubs/work/62904
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Record Id 62904
Title Temperature dependence of low-cycle fatigue behaviour of austenitic stainless steel 316
Abstract Deformation-induced martensite formation is a thermo-mechanical phenomenon whereby the transformation of the austenite phase into martensite occurs above the martensite start temperature due to deformation assistance. A large number of parameters have great influence on the martensite formation, such as applied stress, plastic strain, temperature and steel composition. The deformation induced by the applied load can supply the necessary strain energy to assist martensite formation, and also by introducing defects to promote the nucleation of martensitic grains. Further reduction of temperature provides a large chemical driving force that promotes martensite formation. The stability of the austenitic phase depends on the composition of stainless steel. Low content of Nickel, Chromium or Carbon reduce the stability of austenite and increase the martensite start temperature. This research reported here focuses on the study of martensite formation of in stainless steel 316 during low cycle fatigue at different temperatures. In-situ neutron diffraction was employed for the present investigation in order to perform fatigue tests at temperatures ranging between -200oC to 550 oC. Measurements taken during mechanical testing provide excellent insight into the thermo-mechanics of polycrystalline material deformation, namely, the anisotropy of elastic, plastic and thermal properties at the (average) grain level, the identification of deformation modes (e.g. dislocation slip vs twinning), the evaluation of phase-specific intergranular strains, etc. Room temperature results show martensite formation occurring during fatigue, accompanied by cyclic hardening happened. This is due to the strengthening effect of the martensite through the resistance that its presence offers to plastic slip. Martensite formation during fatigue cycling is also found to be strongly temperature-dependent: while low temperature promotes the transformation, no martensite formation was observed in fatigue tests at 550 oC.
Organisation ISIS , ISIS-ENGIN-X , STFC
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Language English (EN)
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Presentation Presented at 6th International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation, Hamburg, Germany. 2011