Enterprise Name: CHENGDA MODEL SET
Contact person: Business Department
Mobile phone: 198-5734-5006
Address: 39 Success Road, Jiashan Economic Development Zone, Zhejiang Province
Websit : en.chengda-mould.com
At present, the life of die is not high in our country, and the wholesale consumption of die is very large. Therefore, it is an urgent task to improve the life of die in our country. The heat treatment of mould manufacturer has a great influence on the service life. Most of the mould damage we often come into contact with is caused by improper heat treatment. According to statistics, due to improper heat treatment, die failure accounts for more than 50% of the total failure rate. Therefore, vacuum furnace, semi-vacuum furnace and non-oxidation protective atmosphere furnace are more and more used for heat treatment of die abroad.
The die heat treatment process includes matrix strengthening and toughening and surface strengthening. The strengthening and toughening of matrix is to improve the strength and toughness of matrix, reduce fracture and deformation, so its conventional heat treatment needs to be carried out strictly in accordance with the process. The main purpose of surface strengthening is to improve the wear resistance, corrosion resistance and lubricity of the die surface. There are many methods of surface strengthening treatment, such as carburizing, nitriding, sulphurizing, boronizing, nitrocarburizing, metalizing and so on. The service life of the die can be increased several times or even tens of times by using different surface strengthening processes. In recent years, some surface strengthening processes have appeared. This paper mainly introduces three of them.
1. Ion nitriding can be used to improve the corrosion resistance, wear resistance, thermal fatigue resistance and adhesion resistance of dies. The prominent advantage of ion nitriding is that the nitriding time is significantly shortened, the structure of nitriding layer can be controlled by adjusting different gas components, the surface brittleness of nitriding layer is reduced, the deformation is small, the hardness distribution curve of nitriding layer is relatively stable, and it is not easy to produce spalling and thermal fatigue. The permeable matrix material is more extensive than gas nitriding, non-toxic, non-explosive and safe in production. However, it is difficult to obtain uniform heating and homogeneous nitriding layer for complex molds with shallow nitriding layer and steeper transition layer. The temperature measurement and homogeneity of temperature still need to be solved.
The optimum temperature of ion nitriding is 450-520 C. After 6-9 hours of treatment, the depth of nitriding layer is about 0.2-0.3 mm. If the temperature is too low, the infiltration layer is too thin; if the temperature is too high, the surface layer is prone to loose layer, which reduces the ability of anti-sticking die. The optimum thickness of plasma nitriding layer is 0.2-0.3 mm. The worn ion nitriding die can be put into use after repairing and re-nitriding, thus greatly improving the total service life of the die.
2. Nitrocarburizing, Nitrocarburizing process temperature is low (560-570 C), deformation is small, the surface hardness of the treated die steel is up to 900-1000HV, wear resistance is good, corrosion resistance is strong, high temperature hardness, can be used for die casting die, cold heading die, cold extrusion die, hot extrusion die, high-speed forging die and plastic die, respectively, can increase service life by 1-9 times. However, after gas nitrocarburizing, deformation often occurs, and the expansion amount accounts for about 25% of the thickness of the compound, so it is not suitable for precision dies. It must be annealed and remnants removed before treatment.
3. Carbon-nitrogen-boron ternary co-permeation, ternary co-permeation can be carried out in nitriding furnace. The ratio of boron-containing organic agent and ammonia is 1:7, the co-permeation temperature is 600 C, the co-permeation time is 4 h, the thickness of the co-permeation layer compound layer is 3-4 um, the depth of the diffusion layer is 0.23 mm, and the surface hardness is HV011050. The service life of the die increased significantly after co-infiltration treatment.