Microstructure and mechanical properties of a novel medium Mn steel with Cr and Mo microalloying

In this paper, the effects of Cr and Mo microalloying on the microstructure evolution, mechanical properties, and austenite stability of 0.2C-7Mn steel were investigated at different intercritical annealing temperatures plus the same tempering treatment. Both the yield strength and ultimate tensile strength can be enhanced by nano-sized precipitates and solution hardening effect owing to Cr-Mo addition, while the ductility is well retained. The precipitates are mainly distributed on the ferrite matrix of the (Cr, Mo)-added steel, and directly produce a precipitation hardening effect. Due to the precipitation hardening and solution hardening effects of ferrite, the austenite in the (Cr, Mo)-added steel exhibits a lower mechanical stability, and more strain partitioning among the austenite and ferrite can be borne by the austenite than that in the reference steel, resulting in an accelerating transformation of austenite and a prevailed transformation-induced plasticity effect in the (Cr, Mo)-added steel.

Automated summary

This study investigated the effects of Cr and Mo microalloying on the properties of 0.2C-7Mn steel. It was found that the addition of Cr and Mo can enhance the strength of the steel while maintaining ductility, and also affect the microstructure evolution and austenite stability of the steel.