In this study, cryogenic-temperature dynamic mechanical properties of austenitic Fe-(0.4, 1.0)C-18Mn steels were evaluated by conducting dynamic tensile and compressive tests, and deformation mechanisms including tension-compression asymmetry of martensitic transformation behavior were interpreted by microstructural evolution of dynamically tensioned or compressed specimens. After the dynamic tensile test of the 0.4C-18Mn steel, the γ → ε → α′ martensitic transformation occurred at -196 C, whereas ε- or α′-martensite was not found in the 1.0C-18Mn steel. After the dynamic compressive test, on the other hand, the γ → ε martensitic transformation occurred at -196°C without the formation of α′-martensites in the 0.4C-18Mn steel. This dynamic tensile-compressive asymmetry of martensitic transformation was plausibly interpreted by austenite stability in relation with difference in molar volume, hydrostatic stress distribution, and adiabatic heating. The γ → α′ transformation was prevented under the dynamic compressive loading because the increase in molar volume was required for the γ → α′ transformation, whereas it was promoted to induce the γ → ε → α′ transformation under dynamic tensile loading.
Bibliographical noteFunding Information:
This work was supported by POSCO under a contract No. 2013Y049. The authors would like to thank to Mr. Dong Hyun Ahn of POSTECH for his help of FEM analysis works.
© 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- Austenitic high-Mn steel
- Cryogenic temperature
- Dynamic tensile and compressive tests
- TRansformation Induced Plasticity (TRIP)
- TWinning Induced Plasticity (TWIP)
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys