Kinetic analysis of austenite transformation for B1500HS high-strength steel during continuous heating

The dilatometric curves of B1500HS high-strength steel at different heating rates were measured by a Gleeble-3800 thermal simulator and analyzed to investigate the effect of heating rate on austenitization. Results show that the value of starting temperature and ending temperature of austenite transformation increase with the rise of heating rates, whereas the temperature interval of austenite formation decreases. The kinetic equation of austenite transformation was solved using the Johnson–Mehl–Avrami model, and the related parameters of the equation were analyzed by the Kissinger method. For those calculations, the activation energy of austenite transformation is 1.01 × 10⁶ J/mol, and the values of kinetic parameters n and ln k₀ are 0.63 and 103.03, respectively. The relationship between the volume fraction of austenite and the heating time at different heating rates could be predicted using the kinetic equation. The predicted and experimental results were compared to verify the accuracy of the kinetic equation. The microstructure etched by different corrosive solutions was analyzed, and the reliability of kinetic equation was further verified from the microscopic perspective.