Hot rolling die is divided into hammer forging, die forging, extrusion and die casting, including hot forging die, press forging die, stamping die, hot extrusion die and metal die casting die. In addition to the huge mechanical stress, the hot deformation die also bears the repeated heating and cooling, which causes great thermal stress.
In addition to high hardness, strength, red hardness, wear resistance and toughness, hot work die steel should also have good high temperature strength, thermal fatigue stability, thermal conductivity and corrosion resistance. In addition, it is also required to have high hardenability to ensure that the entire section has consistent mechanical properties. For steel used for die casting die, the surface layer shall not crack after repeated heating and cooling, and shall withstand the impact and erosion of liquid metal flow. This kind of steel generally belongs to medium carbon alloy steel, with carbon mass fraction of 0.30%~0.60%. It belongs to hypoeutectoid steel, and some steels become eutectoid or hypereutectoid steel due to the addition of more alloy elements (such as tungsten, molybdenum, vanadium, etc.). Commonly used steels include chrome manganese steel, chrome nickel steel, chrome tungsten steel, etc.
