Analysis and study of distortion and residual stresses in the layer produced from Ti۶Al۴V alloy by selective laser melting method

Selective Laser Melting (SLM) is an Additive Manufacturing (AM) technique used to process Ti۶Al۴V in medicine, aerospace and other industries. In this research, a finite element model using ANSYS software has been used to investigate residual stresses in laser melting of Ti۶Al۴V powders. Initially, a thermal model was developed to calculate the temperature distribution. Then the temperature field results were used for stress field analysis and prediction of residual stresses, deformation due to fabrication. Using a numerical model, the effect of a number of process variables on residual stresses in the printed layer was investigated. In this study, two speeds of ۸۰۰ and ۱۲۰۰ mm/s and a thickness of ۰.۵ and ۱ mm have been used for the build platform. Also, for the printedlayer, two thicknesses of ۳۰ and ۱۵ micrometers are considered. The results showed that with increasing the scanning speed, the longitudinal residual stress increased by ۴۰ MPa and by decreasing the thickness of the printed layer from ۳۰ to ۱۵ μm, the amount of residual stress increased from ۱۳۰ to ۲۳۳ MPa. By reducing the thickness of the build platform from ۱ to ۰.۵ mm, the residual stress decreases to ۱۰۰ MPa, and by changing the material of the platform from steel to titanium alloy, the longitudinal residual stress in the printed layer increases by ۳۰ MPa

Keywords:

Additive manufacturing , Ti۶Al۴V , Residual stress , Selective Laser Melting