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

Abstract

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 (≈13%) than the HR-1373K condition (≈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 γ-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.