1.Casting crack: is a crack formed at higher temperatures.It is easy to occur when the casting volume shrinks and the thermal expansion coefficient is large. 

2.Heat treatment cracks: Due to overburning or overheating of heat treatment, they often appear perforated cracks. 

Causes of cracks: The casting structure design is unreasonable, with sharp corners, and the thickness of the wall is too different.In this case, cracks should be generated and the structural design of the casting should be improved to avoid sharp corners and make the wall thickness uniform and smooth transitions.Bad sand-type concession can also cause cracks.Measures should be taken to increase the concession of sand.Local overheating of the casting mold will cause cracks. It is necessary to ensure that all parts of the casting solidify at the same time or solidify in sequence, and improve the casting system design.Cracks can also be generated when the pouring temperature is too high, so the pouring temperature should be appropriately reduced.When the casting is removed from the self-casting mold, the casting will be deformed too early by thermal correction method. The casting mold cooling and molding time should be controlled.The heat treatment is overheated, and cracks are generated after the cooling speed is overstimulated. The heat correction method is used when the casting is deformed.Correctly control the heat treatment temperature and reduce the quenching cooling speed.