In the process of automobile die making, the heat treatment preparation of die casting die is a very important link. If the preparation is not enough, it will directly lead to defects or even scrap of the final product of die casting die, which also increases the production cost invisibly.
If the organization work before the die-casting die is not enough, the final spheroidizing structure of the die-casting die is uneven and imperfect, and there are network, band and chain carbides in the structure, which will make the die easy to crack after quenching and cause the die to scrap. This is mainly due to the serious carbide segregation in the original structure of die steel, poor forging process, automobile die processing such as high heating temperature, small deformation, high stop forging temperature, slow cooling rate after forging, etc., which makes the forging structure coarse and network, band and chain carbides exist, making spheroidizing annealing difficult to eliminate. Poor spheroidizing annealing process, such as too high or too low annealing temperature and short isothermal annealing time, can cause uneven microstructures or poor spheroidization of spheroidizing annealing.
Therefore, according to the working conditions of die-casting dies, production batches and the strength and toughness of the materials themselves, we should generally choose good quality die steel materials for automobile die processing. Improving forging process or normalizing preparation heat treatment can eliminate the non-uniformity of network and chain carbides and carbides in raw materials. The high carbon die steel with serious carbide segregation which can not be forged can be treated by solid solution refinement heat treatment. Correct spheroidizing annealing process specifications for forged billets can be formulated by means of quenching and tempering heat treatment and rapid homogenizing spheroidizing annealing.