(4) High resistance to melt damage
As the size of the die casting machine increases, the die casting pressure also increases, from 20 to 30 MPa for low pressure to 150 to 500 MPa for high pressure. High temperature and high pressure casting can produce obvious melt damage, and the mold should have greater resistance to this. For this reason, the mold material must have a large high-temperature strength, a small affinity for the molten metal, the mold indicates a small roughness, and a protective layer such as an appropriate oxidation mold, a nitride layer, or the like, without the decarburization layer.
(5) Good hardenability and small heat treatment deformation
Generally, a die-casting mold is manufactured by engraving a cavity of an annealed mold material, and then heat-treating to obtain a desired hardness, or heat-treating the mold material to obtain a desired hardness, and then engraving the cavity. The manufacturing method of the post-cavity cavity post-heat treatment has high hardness and strength, and is not easy to cause melt loss and thermal fatigue. No matter which method is used for heat treatment, it is necessary to obtain uniform hardness, so it is required to have good hardenability. In particular, heat treatment is performed after the cavity is first engraved, and a material having a small heat treatment deformation is used, which is especially true for a mold having a large size. important.