Failure Analysis And Technology Optimization Of Fusion Weling Jiont Of Electromotor Rotor Copper Ring

The reason for the cracking damage in the welding joint of copper ring during the welding production of the electromotor rotor is conducted. On the basis of this research, a new welding technology using welding wire B30 is presented. And high temperature mechanical property of the B30 welding joint is compared with the one of the HS201 welding joint. Moreover, stress field of the two welding wire joints of copper ring during the brazing cooling process is simulated.A large number of liquation cracks are found in the joint of copper ring welded by welding wire HS201. The generation reason of those cracks is that excessive oxygen element entrained in the welding joint makes low-melting eutectic (Cu2O+Cu) generate in the grain boundary of copper under high temperature, which abates intergranular binding force of copper. Mechanical property testing shows tensile strength of the welding joint decreases a lot. Furthermore, the simulation results about stress field of the welding joint during the brazing cooling process show tensile strength of the HS201 welding joint existing welding crack cannot receive tensile stress during this process, which induces the crack or fracture of the welding joint.Based on these failure analyses, a new welding test using welding wire B30 is conducted. Results of high temperature mechanical property test and weld microstructure analysis show tensile strength of the welding joint using welding wire B30 under high temperature is higher than that of the welding joint using welding wire HS201, and even higher than 80% of the tensile strength of the base metal copper. Weld microstructure of the B30 welding joint is better than that of the HS201 welding joint, and no crack is found. The simulation results about stress field of the welding joint during the brazing cooling process show tensile strength of the B30 welding joint can receive tensile stress during this process, which satisfies operational requirement.The welding joint optimization of the copper ring is conducted for settling poor conductivity and high cost of production of the welding joint after using B30 welding wire. The results indicate both compound welding joint and using single V groove instead of single X groove on the welding joint of the copper can satisfy operational requirement.