Effect of Homogenization Treatment on Microstructure, Dendritic Segregation, and Primary Carbides in H13 Steel

In the current work, the dendritic structure evolution, primary carbide dissolution, and austenite grain growth during the homogenization process of H13 steel at 1150-1250 °C were investigated to achieve a balanced improvement in segregation, primary carbide, and grain size controlling. The homogenization kinetic model was established to predict the soaking time needed for eliminating the dendritic structures. The results show that dendritic structures disappear gradually during the homogenization process. The time required for eliminating the dendritic structures of the investigated H13 steel at 1250 °C is 600 min, and those at 1150 and 1200 °C are estimated to be 3.31 and 1.78 times longer than that at 1250 °C. The Mo-rich primary carbides in H13 steel decompose and dissolve completely at the investigated temperature range. However, the V-rich primary carbides could not dissolve completely even at 1250 °C. The decreases in Ti and N content in steel are beneficial for lowering the complete dissolution temperature of V-rich primary carbides. The austenite grains grow slowly at 1150 °C, and become abnormally coarser at 1200-1250 °C.