Heating is an important part of the hot forging process. Hot-forging products are often forged at high and medium temperatures.
To prevent serious oxidation and decarburization on the surface of the blank during heating, it can be heated in an open flame heating furnace with little or no oxidation or other heating furnaces that can effectively control the temperature.
To prevent secondary oxidation during the cooling process of hot forging products, cooling can be carried out in a protected device; the forgings can also be placed in a gridded sand box in an orderly manner. When slow cooling is required, put the forgings in a hot sand box or asbestos powder to cool.
Lowering the heating temperature can prevent strong oxidation and decarburization. As long as it has sufficient plasticity and proper deformation resistance, the purpose of precision die forging can also be achieved. The medium-temperature precision hot forging process is a method of heating and die forging in a temperature range that does not produce strong oxidation.
The strength limit starts to drop sharply from 500°C and drops to half of that at room temperature at 600°C. Above 600℃, the strength limit is low, and all of them can be formed by die forging. Therefore, in the range of 600-875℃, 458 steel has low deformation resistance and no strong oxidation, which can make the forgings achieve higher dimensional accuracy and surface smoothness. Under warm forging conditions, the working temperature of the die is generally around 400℃, and high-speed steel is more suitable for medium-temperature forging die materials.