Microstructure and temperature-dependent mechanical behavior of hot-rolled TRIP-assisted microalloyed steel

Abstract

The effect of deformation temperature (in a temperature range −60 °C–140 °C) on the kinetics of strain-induced martensitic transformation in a hot-rolled multiphase Fe-0.24C-1.5Mn-0.87Si-0.4Al-Nb-Ti steel containing 15% of retained austenite was investigated. A complex microstructural analysis was performed using experimental techniques characterized by different resolutions: the scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The analysis of the tendency of different morphology retained austenite to martensitic transformation was performed. The quantitative analysis of the temperature-dependent stability of γ phase was carried out using the XRD and EBSD methods. The thermodynamic model predicting the changes in the stability of retained austenite at different temperatures was developed based on experimental results. Obtained results showed that both the deformation temperature and morphology of retained austenite affect substantially the stability of retained austenite. • The strategy for designing the stability of retained austenite was developed using experimental and modelling approaches. • The temperature-dependent mechanical behavior of hot-rolled TRIP steel was explained. • The chemical driving force for strain-induced martensitic transformation was determined. • The complex microstructural analysis was applied to link microstructure-properties behavior.