Based on a novel calculation model that considers microstructural changes and latent heat release, evolution of heat transfer coefficients of boron steel in different metallographic states during hot forming die quenching are investigated. Results demonstrate that the evolution of the coefficients in the different metallographic states is significantly different in each state. As blank temperature decreases, no evident fluctuations emerge in the austenitic state, a significant sharp increase followed by a gradual decrease is detected in the multiphase state during martensitic transformation and a slight decrease is observed in the martensitic state. A simulation model for temperature predicting is established by integrating the coefficient data with the finite element software ABAQUS. The numerical results showed good agreement with the experimental results.
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