FEM analysis of thermal and residual stress profile in selective laser melting of 316L stainless steel

摘要

High temperature gradients and resulting large residual stresses are among the most challenging areas of selective laser melting. In order to control these issues, proper understanding of the influence of process parameters on thermal as well as residual stress profile during selective laser melting is of paramount importance. Despite the large number of parametric investigations regarding stress profiles, a lot is yet to be understood especially for 316L stainless steel. Therefore, a 3D FEM model is established in this work to investigate the parametric influence on thermal and residual stress profile in a realistic multi-track multi-layer SLM process. Influences of process parameters on thermal and stress profile were investigated through the experimentally validated FEM model. It was observed that an increase in laser power or a decrease in the scanning speed results in an increased maximum melt pool temperature. Whereas, increasing laser power or scanning speed both increases cooling rates and residual stresses. An increased maximum melt pool temperature and decreased residual stress was observed by increasing the hatch spacing. Residual stress profile was observed to be symmetrical along the scanning direction and non-uniform along the direction perpendicular to the scanning direction. A relatively small residual stress at the top surface and maximum residual stress inside the component around the interface region of powder bed and baseplate was observed.