Hot/cold work mold steel

H13 steel, as a widely used hot work die steel worldwide, can obtain a mixed microstructure of martensite and bainite after normal forging process. It has high hardness and is difficult to cut, so spheroidization annealing is necessary. Spheroidization annealing plays a significant role in eliminating residual stress in steel, reducing hardness, and evenly distributing alloy carbides. It also prepares the microstructure for final quenching and tempering heat treatment.

Slow cooling after forging will result in coarse structure and the appearance of network carbides, while high-temperature normalizing can improve the segregation of network carbides and materials. Therefore, efforts can be made to improve the annealed structure through two aspects: appropriate rapid cooling after forging, high-temperature normalizing, and finally spheroidization annealing.