Hot working die steel high temperature strength, good toughness, wear resistance, high thermal stability, good thermal conductivity and other properties.
Hot working die steel mainly has forging die, hot extrusion die, die casting die and other main failure forms: fracture (crack or mechanical fatigue crack), plastic deformation or cavity collapse, thermal fatigue, thermal wear and hot melt loss. Master of Hot-work Die Steel. Characteristics: in addition to good technological properties, but also requires different temperatures with high strength, toughness, hardness, thermal stability. Generally, the content of C is low and multi-alloying (including Cr, W, Mo, Ni, V, Si, Co, etc.). The main performance requirements of hot working die steel after heat treatment in metal die heat treatment furnace are as follows:
The main results are as follows: 1. Hot working die steel has high temperature strength and good toughness. Hot working dies, especially hot forging dies, bear great impact force when working, and the impact frequency is very high, if the die does not have high strength and good toughness, it is easy to crack.
2. The hot working die steel has good wear resistance. Because of the friction and wear caused by the deformation of the blank, the hot working die steel is also subjected to high temperature oxidation corrosion and grinding of iron oxide filings. Therefore, hot working die steel is required to have higher hardness and anti-adhesion.
3. High thermal stability of hot working die steel. Thermal stability is the ability of steel to keep its mechanical properties at room temperature for a long time at high temperature. Hot work mold work, the contact is hot metal, or even liquid metal, so the mold surface temperature is very high, generally 400, 700 ℃. This requires that the hot working die steel does not heat at high temperature and has high thermal stability, otherwise the die will be plastic deformation, resulting in heap collapse and failure.
4. Hot working die steel has excellent heat resistance and fatigue resistance. The working characteristic of hot working die is that the die is repeatedly heated and cold, the mold is expanded by heat for a time and contracts by cooling for a time, forming great thermal stress, and this kind of thermal stress is in the opposite direction; Alternately. Under the action of repeated thermal stress, the mold surface will form a network of cracks (cracks), this phenomenon known as thermal fatigue, the mold because of thermal fatigue and premature fracture, is one of the main reasons for the failure of hot working die. Therefore, hot working die steel must have good thermal fatigue.
5. Hot working die steel has high hardenability. Hot working die is generally large in size, especially hot forging die. In order to make the mechanical properties of the whole die section uniform, it is required that hot working die steel has high hardenability.
6. Hot working die steel has good thermal conductivity. In order to avoid excessive heat accumulation and decrease mechanical properties of the die, it is necessary to lower the die surface temperature as much as possible and reduce the temperature difference within the mold, which requires the hot working die steel to have good thermal conductivity.
7. Hot working die steel has good forming process performance to meet the needs of forming.