As a widely used product, hot work die steel should be seen often in our life. But What do you know how to tell whether this type of die steel is good or bad? In fact, we can understand it through its basic properties. These aspects are introduced in detail below. Check it out if you're interested.
The hot work die is subjected to a large impact force when working, and the die cavity is in contact with the high temperature metal. It can be repeatedly heated and cooled, so its use conditions are harsh. In order to meet the use requirements of hot work die, hot work die steel should have the following basic characteristics:
1. Good thermal conductivity of hot work die steel
In order to prevent the mold from accumulating too much heat, resulting in the decline of mechanical properties, it is necessary to reduce the temperature of the mold surface as much as possible and reduce the temperature difference inside the mold. This requires hot work die steel to have good thermal conductivity.
2. Good formability of hot work die steel
Hot work die steel has good forming and processing performance to meet the needs of processing and forming
3. High hardenability of hot work die steel
Hot work die steel is generally larger in size, especially for hot forging dies. In order to make the mechanical properties of the entire die section uniform, the hot work die steel is required to have high hardenability.
4. High temperature strength and good toughness of hot work die steel
Hot work dies, especially hot forging dies, are subjected to a lot of impact force when working. And the impact frequency is very high. If the mold does not have high strength and good toughness, it is easy to crack.
5. Good wear resistance of hot work die steel
Because the hot work die is not only subjected to friction and wear when the blank is deformed but also subjected to high temperature oxidation corrosion and grinding of iron oxide chips, the hot work die steel needs to have high hardness and anti-adhesion.
6. High thermal stability of hot work die steel
Thermal stability refers to the ability of steel to maintain its mechanical properties at room temperature for a long time at high temperatures. When the hot work mold is working, it is in contact with hot metal or even liquid metal, so the surface temperature of the mold is very high, generally 400-700 °C. This requires that the hot work die steel does not thermalize at high temperatures and has high thermal stability, otherwise the die will undergo plastic deformation, resulting in collapse and failure.
7. Excellent thermal fatigue resistance of hot work die steel
The working characteristics of hot work die are repeated heating and cooling. The mold expands when heated and shrinks when cooled, forming large thermal stress. And this thermal stress is generated alternately in the opposite direction. Under the action of repeated thermal stress, network cracks (cracking) will form on the surface of the mold. This phenomenon is called thermal fatigue. Premature die fracture due to thermal fatigue is one of the main causes of hot work die failure. Therefore, the hot work die steel should have good thermal fatigue resistance.
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