This work studied microstructure evolution during the intercritical treatment of Fe–1.4Si–2.6Mn–0.17C TRIP steel. Steel specimens were heated in the intercritical region, α ferrite and γ austenite phases, at 750 °C for 30 min, water-quenched, air-cooled, and austempered at 350 °C for 30 min. Microstructural analysis was performed by optical microscopy, scanning electron microscopy, and X-ray diffraction. All heat-treated specimens were mechanically characterized by uniaxial tension and Vickers hardness tests. Thermo-Calc software 2024b was used to analyze the microstructure and phases of heat-treated steel. The microstructural characterization results revealed that the phases and microconstituents were ferrite, austenite, cementite, pearlite, and retained austenite. Thermo-Calc results were consistent with the phases and microconstituents identified for each heat-treatment condition. On the other hand, the tension test results showed that the yield strength and ultimate tensile strength ranged between 690 and 820 MPa and 1190–1255 MPa, respectively, for these heat-treated steels. Likewise, Thermo-Calc proved to be a powerful tool for designing intercritical heat treatments for TRIP steels.
Miranda-López et al. (Wed,) studied this question.