[China Aluminum Industry Net] Cast aluminum is a process method in which molten aluminum is poured into a mold and cooled to form a desired aluminum part. Castings made of cast aluminum are called cast aluminum parts.
Cast aluminum parts are prone to defects such as internal porosity, shrinkage pores, and pores during the casting process. After the castings containing the defects are machined, the surface dense layer components are removed and the internal structural defects are exposed.
Defective appearance:
1. Cast cracks: Cracks formed at higher temperatures. It is easy to occur when the volume shrinkage of the casting is large and the thermal expansion coefficient is large.
2. Heat treatment cracks: Due to overheating caused by heat treatment or overheating, cracks often appear through the crystal.
Causes of cracks:
1. The structural design of castings is irrational, with sharp corners, and the thickness of the walls varies too widely. If cracks occur in this case, the structural design of the casting should be improved to avoid sharp corners, and the wall thickness should strive for a uniform and smooth transition.
2. Poor concretization of the sand type (core) can also produce cracks. Should take measures to increase the sand type (core) concession.
3. Local overheating of the mold will lead to cracks, and it should be ensured that all parts of the casting are solidified or sequentially solidified, and the design of the casting system is improved.
4. Pouring too high a temperature will also produce cracks, and the pouring temperature should be appropriately reduced.
5. Take out the casting from the casting mold and use the heat correction method when the casting is deformed prematurely. The cooling time of the casting mold should be controlled.
6. The heat treatment is overheated, cracks occur after the cooling rate is excessive, and the heat distortion method is used when the casting is deformed. Correctly control the heat treatment temperature and reduce the quench cooling rate.
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