What are the performance requirements of aluminum alloy die casting die steel?
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admin *
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2022/11/30 15:44:00 *
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What are the performance requirements of aluminum alloy die casting die steel? It is mainly used for parts of some instruments. According to the service conditions and common failure forms of aluminum alloy die casting die, the main performance requirements for steel used for aluminum alloy die casting die are as follows:
1. High tempering resistance and cold and hot fatigue resistance
The aluminum alloy die-casting die produced continuously in large quantities shall keep its high hardness under the action of a certain temperature for a long time, and shall not stick to the die and produce oxide skin. Therefore, the die should have good oxidation resistance and tempering stability.
The surface of aluminum alloy die casting die is repeatedly heated and cooled by high temperature, constantly expanding and shrinking, generating alternating thermal stress. When this stress exceeds the elastic limit of the die material, repeated plastic deformation occurs, causing thermal fatigue.
At the same time, the mold surface is corroded and oxidized by molten metal for a long time, which will gradually produce micro cracks. In most cases, thermal fatigue is an important factor determining the life of the die casting mold.
2. Sufficient strength, hardness, plasticity and heat resistance
The aluminum alloy die casting die is easy to deform and even crack due to the high temperature, high pressure and thermal stress when molten metal is injected. Therefore, the die steel should have sufficient high temperature strength and toughness, as well as high hardness and heat resistance at the working temperature.
3. Good thermal conductivity
The aluminum alloy die casting die is under the high temperature of 600-700 ℃ for a long time. In order to ensure other properties, it must have good thermal conductivity.
4. Good resistance to damage of molten metal
With the large-scale die-casting machine, the die-casting pressure is also increasing, from 20-30MPa at low pressure to 150-500MPa at high pressure. High temperature and high pressure casting can produce obvious melting damage, and the mold should have greater resistance to this.
For this reason, the mold material must have higher high temperature strength, lower affinity to molten metal, and the mold indicates that the roughness should be small, with appropriate protective layers such as oxidation mold and nitriding layer attached, and there is no decarburization layer.
5. Good permeability, small heat treatment deformation
In general, the manufacturing method of die-casting die is to carve the cavity of the annealed die material, and then conduct heat treatment to obtain the required hardness; Or heat treat the mold material to obtain the required hardness before carving the cavity.
The manufacturing method of carving cavity before heat treatment has high hardness and strength, and is not easy to produce melting loss and thermal fatigue.
No matter which method is used for heat treatment, it is necessary to obtain uniform hardness. Therefore, it is required to have good hardenability, especially when the cavity is carved first and then the heat treatment is carried out. Materials with small deformation should be used for heat treatment, which is particularly important for molds with large size.
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