Fracture reason of 45 steel ring

The fracture of a 45 steel ring occurred during quenching. The fracture causes of the steel ring were analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination and hardness test. The results show that the fracture property of the steel ring was quenching fracture, and the higher heating temperature and quenching stress formed by water cooling were the main reasons for its fracture. There were a large number of MnS inclusions distributed along the circumferential direction in the matrix of the part, which seriously cut the continuity of the matrix and promoted the fracture of the core.