An investigation on anomalous deformation behavior in SUS304 austenitic stainless steel: Experiments and simulations

During tensile testing of thin specimen made of metastable austenitic stainless steels, the movement of the X-shaped localized deformation band (LDB) accompanied by stress serrations was observed. Investigating this anomalous deformation behavior is crucial to enhancing the performance and applicability of these steels. In this study, tensile tests were conducted on thin tensile specimens of SUS304 stainless steel at various strain rates, and the movement of the LDB was captured using the conventional digital image correlation (DIC) method. To reproduce the phenomenon of LDB movement, 3D finite element analysis was performed, where dynamic strain aging (DSA) is considered for the reference stress of the austenitic and martensitic phases, respectively. The analytical model focused on a 1/8 region, and the 1/4 regions were extended in the longitudinal and width directions to represent characteristic features. A modified mathematical model of DSA was employed, with parameter adjustments to better reproduce the observed behavior. Additionally, environmental temperature was also varied to study its effect on the deformation behavior of thin plate and round bars, allowing for a comparison of their differences. These investigations provide deeper insight into the mechanisms underlying the anomalous deformation behavior in SUS304 stainless steel.