SLM is characterized by selective zone melting and rapid metal cooling after melting. Therefore, there is an obvious difference in temperature field between the melted part and the unmelted part in the forming process, resulting in a large temperature gradient in the forming process, and at the same time, residual stress is easy to occur in the rapid cooling process. In the process of selective melting, the metal is squeezed by the unmelted part due to the thermal expansion effect of the melted part, resulting in a compressive stress