The effect of support structure on residual stress in laser powder bed fusion of Ti6Al4V alloy

Abstract

Support structures are widely used in laser powder bed fusion (LPBF) for overhanging features. However, the majority of works carried out on support modeling were to obtain the best trade-off between production time, cost, and accuracy. A notable absence in the existing literature pertains to investigate support structure modeling for optimizing heat dissipation and residual stresses for improving the support structure, thus, enhancing the final part quality. In this study, the effects of the support structure on residual stress were investigated systematically. The influences of the support on residual stress in LPBF sample were categorized into the effect of the constraints and heat conduction area. The rigidity and area of the support structure are used to describe the effect of the support structure on the residual stress. The results showed that the constrain of LPBF samples mainly depends on their inherent characteristics, with limited impact from external constraints. The residual stress in the samples increased as the support area increased. Therefore, when designing the support, priority should be given to reduce its thermal conductivity area. In addition, the hardness of the support added sample were lower than that of the sample without the support, but the hardness distribution is uniform along the deposition height regardless of whether the support is added or not. Therefore, the introduction of support does not result in performance irregularities along the sample height direction.

Keywords

• Laser powder bed fusion
• Residual stress
• Support structure
• Ti6Al4V