The reasons for the low life of die casting molds involve many factors, such as materials, processing, heat treatment, maintenance, and repair, which will affect the life of the mold.The thermal fatigue phenomenon of the mold during casting is related to the toughness, ductility, crack progress rate, etc. of the mold steel and the characteristics of the material. The mechanical stress generated during the operation is also the cause.On the other hand, the dissolution phenomenon is also very different due to the reactivity and contact friction of the mold material and the molten metal.The reaction pattern is also due to die-cast metal types (AI、Mg、Zn There are differences in the same.In addition, the stability and improvement of the mold during operation are also closely related to its maintenance and repair technology, such as the improvement of the deteriorated layer of electrically processed, the selection of welding conditions, and the adjustment of deformation.The heat treatment of mold steel is a very important basic technology to effectively exert the functions and performance of the material. The performance of heat treatment is significantly different.No matter how good the steel is, if the appropriate heat treatment is not properly, the mold will cause thermal cracking, cutting, and many other faults during operation.In recent years, the heat treatment of mold steel has been mostly used to use vacuum air pressurized heat treatment furnaces, mainly because it can improve the operating environment, bright heat treatment of the mold, high pressure during cooling, and large-scale heat treatment furnaces can be manufactured.Vacuum pressurized gas cooling methods, traditional water quenching, oil quenching, polymer quenching, salt bath quenching, etc., have generally achieved the same cooling speed in recent years, and can also be treated with less soft points.In recent years, with the increase in mold size, steel grades for large molds that improve quenching performance have been developed.The heat treatment of large molds has great differences in cooling speeds at the center of the surface layer, and uneven heat treatment causes deformation, deformation, and splitting.Therefore, it is very important to control the temperature difference between the inside and outside during the cooling process. No matter how good the steel type is, it is difficult to exert its characteristics by unstable heat treatment.The North American Die Casting Association has set standards for the quality requirements and heat treatment of die casting molds. Its main items include: 1. Material composition 1. Hardness (annealing, quenching －Tempering treatment) 3. The cleanliness of the material is ( ASTM、A－681、Sec6 Let's make a judgment )4、Ultrasonic flaw detection test (Internal defect inspection )、Impact test (Determination of stuntity and ductility )6、Crystallization particle size 7, microsegregation 8, annealed structure, etc.All countries, regions, suppliers and manufacturers can have a unified recognition of mold steel, mold processing, heat treatment and other aspects, which is beneficial to improving the quality and production of die casting molds.
