Breaking the strength-ductility trade-off in austenitic stainless steel at cryogenic temperatures: Mechanistic insights
At cryogenic temperatures, 316L austenitic stainless steel (ASS) exhibits remarkable strength while retaining high ductility, defying the conventional stress-strain trade-off. Despite extensive studies documenting the cryo-tensile properties of ASSs, the underlying mechanisms behind this phenomenon...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2024-11-01
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| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785424020799 |
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| Summary: | At cryogenic temperatures, 316L austenitic stainless steel (ASS) exhibits remarkable strength while retaining high ductility, defying the conventional stress-strain trade-off. Despite extensive studies documenting the cryo-tensile properties of ASSs, the underlying mechanisms behind this phenomenon remain largely unexplored. This study systematically re-examines the tensile properties of 316L stainless steel and the associated mechanisms across a range of low temperatures (293 K, 223 K, 123 K, and 77 K). The reasons for the superior stress-strain balance (∼80 % GPa) are discussed using results from electron backscatter diffraction (EBSD) microstructure characteristics. The results undoubtedly suggest that the transformation mechanisms, specifically the shift from deformation twinning to martensitic transformation (γ → ε → α′), play a crucial role in enhancing elongation at cryogenic temperatures. At these temperatures, the Gibbs free energy difference between ε-martensite and γ-austenite approaches zero, resulting in slow martensite growth. The stress-strain curves at low temperatures satisfy the Considère criterion, indicating delayed necking under these conditions. This behavior is ascribed to the presence of various hierarchical microstructures, including ε, α′, γ-twins, ε-twins and their intersections, which act as sources of work hardening. This study provides new insights into deformation behavior of ASSs under cryogenic conditions. |
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| ISSN: | 2238-7854 |