Study on the Mechanical Stability of Retained Austenite in Cold-Rolled Medium-Mn Steel

Abstract

The mechanical stability of the retained austenite in the cold-rolled medium-Mn steel was studied. Tensile tests were carried out to measure the mechanical properties of the annealed steel. Scanning electron microscopy was applied to characterize the microstructure evolution during the tensile process; X-ray diffraction analysis was used to determine the residual austenite content in the deformed steel. It was found that the volume fraction of retained austenite gradually decreases with strain .The value of the stability coefficient of retained austenite k was small in the test steel, which indicated high mechanical stability of retained austenite. Due to TRIP effect, the high mechanical stability of the retained austenite strongly delays the onset of necking, which resulted in good comprehensive mechanical properties with ultrahigh strength and plasticity.