Ultrahigh strength-ductile medium-Mn steel auto-parts combining warm stamping and quenching & partitioning.

A novel application of quenching and partitioning (Q&P) treatment to warm stamping of a warm-rolled medium Mn steel was investigated. The results show that Q&P could improve yield strength of auto-parts from the formation of carbides and twinned martensite, and reduce the yield point elongation for carbon partitioning during Q&P process and a higher dislocation density. Regardless of stamping temperature either the single austenite or dual-phase region, an extraordinary product of strength and ductility (≥24 GPa·%) was achieved, which is two or three times higher than those of hot-stamped boron steels. The combined warm rolling and warm stamping process with Q&P treatment may have potential to implement the application of medium Mn steels for ultrahigh strength-ductile auto-parts. [ABSTRACT FROM AUTHOR]