Load Partitioning and Strain-Induced Martensite Formation during Tensile Loading of a Metastable Austenitic Stainless Steel

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 40; no. 5; pp. 1039 - 1048
• Main Authors: Hedström, P., Lindgren, L. E., Almer, J., Lienert, U., Bernier, J., Terner, M., Odén, M.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.05.2009; Springer; Springer Nature B.V
• Subjects: Alloys; Applied sciences; AUSTENITE; Austenitic stainless steel; Characterization and Evaluation of Materials; Chemistry and Materials Science; DEFORMATION; Engineering Materials; Exact sciences and technology; FRACTURES; HEATING; Load; MARTENSITE; Material Mechanics; Materialmekanik; MATERIALS SCIENCE; Materialteknik; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; NATURAL SCIENCES; NATURVETENSKAP; SENSITIVITY; SIMULATION; STAINLESS STEELS; STRAIN RATE; STRAINS; Structural Materials; Surfaces and Interfaces; TECHNOLOGY; TEKNIKVETENSKAP; TEMPERATURE DISTRIBUTION; Tensile strength; Thin Films; TRANSFORMATIONS; X-RAY DIFFRACTION; Martensitic Transformation; Transformation Behavior; Martensite; Shear Band; Austenite; Austenitic stainless steel; Austenitic steel; Stainless steel
• ISSN: 1073-5623; 1543-1940; 1543-1940
• DOI: 10.1007/s11661-009-9807-3

In-situ high-energy X-ray diffraction and material modeling are used to investigate the strain-rate dependence of the strain-induced martensitic transformation and the stress partitioning between austenite and α ′ martensite in a metastable austenitic stainless steel during tensile loading. Moderate changes of the strain rate alter the strain-induced martensitic transformation, with a significantly lower α ′ martensite fraction observed at fracture for a strain rate of 10 −2  s −1 , as compared to 10 −3  s −1 . This strain-rate sensitivity is attributed to the adiabatic heating of the samples and is found to be well predicted by the combination of an extended Olson–Cohen strain-induced martensite model and finite-element simulations for the evolving temperature distribution in the samples. In addition, the strain-rate sensitivity affects the deformation behavior of the steel. The α ′ martensite transformation at high strains provides local strengthening and extends the time to neck formation. This reinforcement is witnessed by a load transfer from austenite to α ′ martensite during loading.