A Medium-Mn Steel Stamped Parts Overcoming Lüders Deformation by Increasing Dislocation Density

This study investigates a novel forming design, that is, intercritical rolling (IR) + low-temperature rolling (LTR) + short-time intercritical annealing (STIA) + one-step stamping (OSS), to decrease or eliminate the yield point elongation (YPE) in a medium-Mn alloy. Results show that the novel forming design leads to ultra-fine microstructure and excellent mechanical properties in the stamped parts. The dislocation density or austenite mechanical stability may be the underlying reasons for the decreased YPE in medium-Mn steels. This novel forming design can increase the work hardening exponent of experimental samples by increasing the dislocation density in ferrite or decreasing austenite mechanical stability, resulting in a continuous yielding feature in stamped parts.