HUI Pengbo, XIAO Guizhi, WANG Xin, MO Jinqiang, ZHANG Liangliang, ZOUDening
Austenitic stainless steel (ASS) shows great application potential in the field of hydrogen storage and transportation, yet it is characterized by low strength and excessive plasticity. Strain strengthening technology can significantly enhance material strength by utilizing partial plasticity, with the strain level being a key factor influencing microstructure and mechanical properties. The effects of different pre-strain levels (0, 5%, 10%, 15%) on the microstructure and mechanical properties of ASS were systematically investigated. The results show that with increasing strain, the yield strength of the tested steel increases significantly, the tensile strength increases slightly, the total elongation decreases, and the yield ratio exhibits an upward trend. At a strain of 10%, the yield strength reaches 535.2MPa, the tensile strength is 697.5MPa, the total elongation is 56.2%, and the yield ratio is 0.77, achieving a reasonable utilization of redundant plasticity. Analysis indicates that the increase in yield strength is mainly attributed to the formation of dislocation bands, dislocation cells and dislocation tangles during the strain strengthening process. After tensile deformation, the proportion of twin boundaries increases slightly, while twin thickness and spacing decrease significantly, which facilitates strain dispersion at the microscale and alleviates stress concentration. Moreover, the large number of parallel and intersecting twins generated during tensile deformation increases the tortuosity of crack propagation paths, thereby enhancing plasticity. Therefore, the primary deformation mechanism of the tested steel is the twinning-induced plasticity effect.
