Unveiling the Correlation among Microstructure, Texture, Slip System Activity, and Tensile Property in a Hot Rolled Ni Containing Medium-Mn Steel

The microstructure-texture-tensile property relationships in a Ni-containing medium-Mn steel (Ni-MMS), subjected to limited thermomechanical processing steps (i.e., hot forging and hot rolling), have been established in this study. The microstructure of the specimens hot rolled (HR) at 1173 (HR-1173K) and 1373 K (HR-1373K) exhibits ferrite and austenite phases. The austenite phase fraction in the HR-1173K specimen is found to be higher than the HR-1373K condition. The volume fraction of austenite to martensite transformation during tensile testing is also observed to be higher in the HR-1173K specimen (approximate to 13%) than the HR-1373K condition (approximate to 2%). This suggests the occurrence of more efficient transformation-induced plasticity effect in the HR-1173K specimen in comparison to the HR-1373K condition, resulting in improved strength-ductility synergy in the former specimen. The smaller grain size of both the phases and higher fraction of twin boundaries as well the evolution of higher intensity gamma-fiber <111>//ND in the HR-1173K specimen leads to better tensile properties. In addition, the overall activation of the primary slip systems (combination of face-centered cubic and body-centered cubic phases slip system), estimated through visco-plastic self-consistent simulation, is higher in HR-1173K specimens, resulting in improved strain hardening response as compared to HR-1373K one.