In the process of making automotive molds, the heat treatment preparation of die-casting molds is a very important link. If the preparations are not adequately done, it will directly lead to defects in the final product of the mold or even scrapping, which is also an increase invisibly Cost of production.
If the organization work before the die-casting die is not enough, the final spheroidization structure of the die-casting die will be coarse and uneven, and the spheroidization will be imperfect. The structure has mesh, band and chain carbides, which will make the die prone to cracks after quenching , Causing the mold to be scrapped. The main reason for this is that the original structure of the die steel material has serious carbide segregation, the forging process is not good, and the automotive die processing such as forging heating temperature is too high, the deformation is small, the stop forging temperature is high, and the cooling rate after forging is slow. The forging structure is coarse and there are network, band and chain carbides, which makes it difficult to eliminate during spheroidizing annealing. Poor spheroidizing annealing process, such as too high or too low annealing temperature, short isothermal annealing time, etc., can cause uneven spheroidizing annealing organization or poor spheroidization.
Therefore, we should generally choose high-quality mold steel materials for automobile mold processing according to the working conditions of the die-casting mold, the production batch and the strength and toughness of the material itself. Improve the forging process or use normalizing and pre-heat treatment to eliminate the unevenness of the network and chain carbides and carbides in the raw materials. High-carbon die steels with severe segregation of carbides that cannot be forged can be subjected to solution refinement heat treatment. To formulate the correct spheroidizing annealing process specification for the forging die blank, quenching and tempering heat treatment and rapid uniform spheroidizing annealing can be adopted.