Low-carbon and environmentally friendly new energy electric vehicles are becoming increasingly popular and have become the mainstream trend for people when buying cars. In electric vehicles, the motor is one of the core components, replacing the engine and generator of traditional cars and directly affecting the power performance and economy of the vehicle. The motor shaft, as a key component of the motor, is prone to be affected by alternating bending force and torsion force during operation, which requires very high quality standards for the surface and interior of the used materials.