Numerical study of residual stress in TC4 alloy manufactured by laser directed energy deposition: comparison of three heat sources

Purpose Laser directed energy deposition (LDED) is an additive manufacturing technique. The shape of the laser heat source has a direct impact on the residual stress in LDED process. This paper aims to study the effects of three different heat sources on the residual stress in LDED process of TC4 alloy, with the goal of enabling residual stress control through optimized heat source. Design/methodology/approach Three different heat source models are established, namely, Gaussian heat source (GDHS), flat top heat source (FTHS) and annular heat source (ADHS) models. The microstructure of the deposition samples is analyzed, and the residual stress is measured using X-ray diffraction to validate the accuracy of the numerical simulations. Findings The results show that significant differences in the residual stress fields generated by the three heat sources. In the same laser power and deposition rate, both FTHS and ADHS are more effective than GDHS in suppressing residual stress, with ADHS exhibiting the most pronounced reduction. Moreover, a positive correlation between laser energy and residual stress magnitude is observed. For different deposition layers, the lower layers exhibited relatively lower residual stress, while the upper layers showed higher stress levels. Originality/value To the best of the authors’ knowledge, this paper is the first to compare the application of three different heat sources in LDED process of TC4 alloy, systematically analyzing their effects on residual stress. This paper provides theoretical and methodological support for the control of residual stress.