Reasons Analysis on Deformation of Cylinder Cover of an Automobile Engine

The deformation reasons of a cylinder cover were analyzed by means of bolt bending torque testing, hardness testing, metallographic examination, chemical compositions analysis and verification testing. The results show that the lower aging temperature made hardness of the cylinder cover was higher than the specified scope. During the cylinder working, because the actual temperature of the intermediate zone of two cylinders’ exhaust sides was higher than the aging temperature action, overaging would happen after long time high temperature, which resulted in the hardness decreasing and hollow deformation.