The heat treatment process of parts requires the internal stress to be controlled while ensuring the required hardness of the part, so as to ensure dimensional stability during processing. Different materials have different treatment methods. With the development of the mold industry in recent years, the types of materials used have increased. In addition to Cr12, 40Cr, Cr12MoV, and cemented carbide, for some convex and concave molds with high work strength and severe stress, new material powder alloy steels can be used. Such as V10, ASP23, etc., such materials have a high thermal stability and a good organization.
For parts made of Cr12MoV, quenching is performed after rough machining. After quenching, there is a large residual stress in the workpiece, which can easily lead to cracking during finishing or work. After the part is quenched, it should be heated and tempered to eliminate quenching stress. The quenching temperature is controlled at 900-1020°C, then cooled to 200-220°C and air-cooled, and then rapidly returned to 220°C for tempering. This method is called a hardening process and can obtain high strength and wear resistance for wear. The main failure mode of the mold is better. In the production, some workpieces with many corners and complex shapes are encountered. Tempering is not enough to eliminate the quenching stress. Before the finishing process, stress relief annealing or multiple aging treatments are required to fully release the stress.
For V10, APS23 and other powder alloy steel parts, because they can withstand high temperature tempering, quenching can be used when the secondary hardening process, 1050-1080 °C quenching, and then 490-520 °C high temperature tempering and multiple times, you can get more High impact toughness and stability are suitable for molds with chipping as the main failure mode. Powder alloy steel has a high cost, but its performance is good, and it is forming a wide application trend.