Recovering the ductility of medium-Mn steel by restoring the original microstructure

Abstract

To recover the reduced ductility of cold-worked medium-Mn steels, a novel resetting process is proposed in this study. Through a simple heat treatment, the original microstructure of the steel is restored by the re-reversion of the Mn-enriched strain-induced martensite. The ductility of the reset steel is successfully recovered, and its strength is improved, relative to the steel prior to cold working. The present technique facilitates the use of a single sheet metal and a simple heat treatment process for an automotive component which originally comprised two different parts to compensate for the opposing attributes that it requires (e.g., having a high strength at the upper part and high toughness at the bottom part of a center pillar).