期刊
出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2022.144118
关键词
Medium Mn lightweight steel; Hierarchical structure; Transformation-induced plasticity; Twinning-induced plasticity; Hetero-deformation induced stress
类别
资金
- Natural Science Foundation of China [51671149/52274379]
- Fundamental Research Funding of the Central Universities in China [N2002002/N180702012]
- Key R&D and Promotion Special Project of Henan Province [212102210444]
This study reports a tri-phase hierarchical lamellar structure to achieve a balance between ultra-high yield strength and high ductility in a Si-Al added medium Mn lightweight TRIP/TWIP steel. By subjecting the warm-rolled sample to small cold rolling and low-temperature tempering, a nano-scale twins and martensitic laths were obtained in the austenitic matrix along with the hard delta-ferrite and nano-precipitates. The tempered sample exhibited a yield strength of 1403 MPa, which was 370 MPa higher than the warm-rolled counterpart. The propagation of plastic strain was confined by the hard zone (delta-ferrite), resulting in an intrinsic hetero-deformation induced (HDI) strengthening effect. The large ductility of 30% was attributed to the elongation of the yield point and enhanced strain hardening after the Luders strain, which were closely associated with HDI hardening and additional TRIP/TWIP effects.
The present work reports a tri-phase hierarchical lamellar structure to tailor the ultra-high yield strength and high ductility balance in a novel Si-Al added medium Mn lightweight TRIP/TWIP steel. The warm-rolled sample was subjected to small cold rolling and low-temperature tempering to obtain the nano-scale twins and martensitic laths in the austenitic matrix, together with the hard delta-ferrite with nano-precipitates. The yield strength of 1403 MPa was obtained in the tempered sample, which is 370 MPa higher than the warm-rolled counterpart. Interestingly, the hard zone (delta-ferrite) confined the propagation of the plastic strain, leading to an intrinsic hetero-deformation induced (HDI) strengthening effect. The large ductility of 30% was ascribed to the large yield point elongation and the enhanced strain hardening after the Luders strain, which is closely associated with HDI hardening and extra TRIP/TWIP effects.
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