Cracking Causes of Rotor Bar of Reactor Coolant Pump Motor

Aiming at the problem of cracking in a rotor bar of reactor coolant pump motor during manufacturing, the failure reasons were analyzed by analysis and observation of chemical composition, mechanical properties, fracture morphology and microstructure. It was found that the fracture of rotor bar showed an characteristic of intergranular brittle fracture. The initial crack in rotor bar was generated in the process of high temperature extrusion and expanded in the subsequent drawing process. The manufacture process of rotor bar was improved by optimizing parameters and strengthening quality inspection according to the cause of crack, and the optimized rotor bar had no obvious crack defects.