Temperature Dependence of Deformation Behaviors in High Manganese Austenitic Steel for Cryogenic Applications

• Published in: Materials Vol. 14; no. 18; p. 5426
• Main Authors: Chen, Jun, Li, Shuang, Ren, Jia-Kuan, Liu, Zhen-Yu
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 19.09.2021; MDPI
• Subjects: Austenitic stainless steels; Automobile industry; Deformation; dislocation structure; Ductility; Electron backscatter diffraction; Elongation; high manganese austenitic steel; Hot rolling; Liquefied natural gas; Manganese; Manganese steel; Mechanical properties; Mechanical twinning; Strain hardening; strength and ductility; Temperature; Temperature dependence; Tensile deformation; Ultimate tensile strength; Yield strength; Yield stress; Germany
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14185426

The deformation structure and its contribution to strain hardening of a high manganese austenitic steel were investigated after tensile deformation at 298 K, 77 K and 4 K by means of electron backscatter diffraction and transmission electron microscopy, exhibiting a strong dependence of strain hardening and deformation structure on deformation temperature. It was demonstrated that sufficient twinning indeed provides a high and stable strain hardening capacity, leading to a simultaneous increase in strength and ductility at 77 K compared with the tensile deformation at 298 K. Moreover, although the SFE of the steel is ~34.4 mJ/m2 at 4 K, sufficient twinning was not observed, indicating that the mechanical twinning is hard to activate at 4 K. However, numerous planar dislocation arrays and microbands can be observed, and these substructures may be a reason for multi-peak strain hardening behaviors at 4 K. They can also provide certain strain hardening capacity, and a relatively high total elongation of ~48% can be obtained at 4 K. In addition, it was found that the yield strength (YS) and ultimate tensile strength (UTS) linearly increases with the lowering of the deformation temperature from 298 K to 4 K, and the increment in YS and UTS was estimated to be 2.13 and 2.43 MPa per 1 K reduction, respectively.