This paper highlights some recent efforts to extend the use of medium-Mn steels for applications other than intercritically batch-annealed steels with exceptional ductility (and strengths in the range of about 1000 MPa). These steels are shown to enable a range of promising properties. In hot-stamping application concepts, elevated Mn concentration helps to stabilize austenite and to provide a range of attractive property combinations, and also reduces the processing temperatures and likely eliminates the need for press quenching. The “double soaking” concept also provides a wide range of attractive mechanical property combinations that may be applicable in cold-forming applications, and could be implemented in continuous annealing and/or continuous galvanizing processes where Zn-coating would typically represent an additional austempering step. Quenching and partitioning of steels with elevated Mn concentrations have exhibited very high strengths, with attractive tensile ductility; and medium-Mn steels have been successfully designed for quenching and partitioning using room temperature as the quench temperature, thereby effectively decoupling the quenching and partitioning steps.

Nitrogen-annealed tensile specimens of a cold rolled medium Mn (9.76 wt%) steel exhibited significantly reduced ductility due to a two-zone embrittled surface layer, imparted during annealing in a nitrogen atmosphere. The embrittlement was associated with high nitrogen contents at the surface.