Effect of partitioning temperature on the microstructure and evolution of medium manganese steel

The Q&P process of hot-rolled medium manganese steel (0.11C, 4.95Mn, 1.6Si,0.34Crwt-%) was studied and annealing at 660°C was selected to investigate the mechanism of microstructure evolution of medium manganese steel at different partitioning temperatures, and SEM, EBSD, XRD and transmission electron microscopy were used to analyse and observe the medium manganese steel. The results show that the partitioning temperature affects the distribution of martensite and austenite, with the parallel distribution of martensite being thicker and longer, making the austenite distributed between them more stable; the retained austenite at the boundary of the short rod-like martensite is subjected to larger deformation forces and is less stable. The best overall performance of the test steel was achieved when the partitioning temperature was 230°C, with a total elongation after breaking of 27.4%, and the product of tensile strength and elongation was 34.8 GPa-%.