Microstructure and Mechanical Properties of Medium-Mn Steel with Different Rolling Processes after I&Q&P Heat Treatment

0.1C-7.2Mn hot-rolled sheet of medium-Mn steel were subjected to hot rolling, intercritical rolling and cold rolling with a reduction ratio of 40%, respectively, and original samples of hot rolling, warm rolling and cold rolling with different microstructure at room temperature were obtained. Then the same I&Q&P heat treatment was carried out for different rolled original samples. The room temperature microstructure of the original sample and the heat treatment sample was observed by means of scanning electron microscope（SEM）. The mechanical properties of heat-treated specimens were compared by roomtemperature tensile test. The results show that there are two kinds of retained austenite morphology in warm rolling I&Q&P samples: isometric and strip shaped retained austenite. The tensile curve of the hot rolling and cold-rolled I&Q&P samples is about 2.6% of the yield platform. The intercritical rolling I&Q&P sample shows continuous yield phenomenon, and there is no obvious yield platform. The intercritical rolling I&Q&P sample has the highest strong plastic product, up to 21.3 GPa%.