Microstructure optimization by combinatorial approach applied to Duplex Medium Manganese steels

A novel high-throughput strategy was employed to investigate phase transformation kinetics in medium-Mn steels using in situ high-energy X-ray diffraction (HEXRD) during intercritical annealing. By imposing a controlled temperature gradient (680–720 °C) on a single sample, the method enabled real-time monitoring of austenite formation across a continuous thermal spectrum. Unlike conventional isothermal tests, this approach significantly improved the spatial and thermal resolution of kinetic data. The present dataset was obtained during in situ High Energy X-Ray Diffraction experiments performed at the European Synchrotron Radiation Facility (ESRF) at ID31 beamline during two sessions of experiments in February and in July 2024. The studied alloy had a nominal composition of Fe–0.2C–4Mn–1.5Si–0.8Al (wt.%), and the sample dimensions were 30 × 1.6 × 6 mm³. Prior to HEXRD measurements, samples were austenitized at 900 °C for 5 minutes and water-quenched to obtain a fully martensitic starting microstructure. Then, during the in situ HEXRD experiment, heat treatments were performed using a custom-built furnace. The thermal cycle involved controlled heating at 1 °C/s to the intercritical holding temperature, followed by a 900 s isothermal hold and subsequent quenching to room temperature using helium gas.