Role of Solidification Behavior and Various Processing Routes on Microstructure–Property Correlation in Medium-Mn Steels with and without Nickel: Recent Progresses and Perspectives

Variations in alloying contents, thermo-mechanical processing (TMP), and heat treatment (HT) routes provide a range of excellent mechanical properties in medium-Mn steels (MMnS). However, solidification defects limit the industrial production of MMnS as it belongs to the peritectic class of alloys. Considering recent progress, it mandates a comprehensive review of the role of solidification behavior and various processing routes on microstructure–property correlation. Hence, the present article addresses microstructure evolution during solidification, TMP, HT, and corresponding mechanical properties. Quenching & partitioning (Q&P) and intercritical annealing (IA) are considered for the present review. It is observed that δ-ferrite transforms to austenite by a massive transformation mechanism after the peritectic reaction. High strength but low elongation is found in Q&P as compared to IA MMnS. Further, the occurrence of discontinuous yielding is associated with both HT routes. However, it is preventable with process parameters. Ni addition generally enhances the strength–ductility balance in comparison with Ni-free MMnS. However, it primarily depends on microstructural characteristics such as phase fraction, distribution, morphology, degree of recrystallization, precipitates, and retained austenite stability. Thus, optimum processing routes can be designed considering the aforementioned factors.