铸件因为形状复杂,截面厚薄不同等原因(尤其是大铸件,例如机床的床身,发动机的汽缸体等),所以在浇铸时,冷却速度就不会一致。也就是铸件在冷却过程中,铸铁由塑性变形范围改变到弹性变形范围的一段过程内,在截面厚薄不同的地方,温度就会不一致,因而就产生了不平均的拉力,这就是残余内应力(通常称用铸造应力)产 Due to the complexity of the shape of the casting, the thickness of the cross-section and other reasons (especially large castings, such as machine tool bed, engine cylinder block, etc.), so when casting, the cooling rate will not be the same. That is, the casting in the cooling process, cast iron from the plastic deformation range to a range of elastic deformation within a section of the thickness of different cross-section, the temperature will be inconsistent, resulting in uneven tension, which is the residual stress ( Casting stress is usually called) production