Comparative Study of IQP Process on Two Distinct Initial Microstructures in Medium-Mn Steel

This study focuses on the comparative analysis of the IQP (Intercritical Quenching and Partitioning) process on two different initial microstructures in medium-Mn steel. The steel composition is Fe-0.25C-3.08Mn-1.5Si-0.054 Nb, wt%. The ingots were produced through laboratory smelting and subsequently hot rolled to 4.5 mm with a coiling temperature of 650 °C. Rectangular specimens were machined from the cold-rolled sheets, aligned parallel to the rolling direction. Heat treatment experiments were conducted on a continuous annealing simulator, involving three intercritical annealing temperatures of 720 °C, 740 °C, and 760 °C to achieve different phase proportions. Partition processing was performed at 400 °C for 60 s, with distinct quenching temperatures tailored for each specimen. The study also included another initial microstructure after cold rolling, subjected to the same treatment.