A Review of Strategies for In Situ Mitigating of Residual Stress in Laser-Based Metal Additive Manufacturing: Insights, Innovations, and Challenges

Additive manufacturing (AM) has emerged as one of the most utilized processes in manufacturing due to its ability to produce complex geometries with minimal material waste and greater design freedom. Laser-based AM (LAM) technologies use high-power lasers to melt metallic materials, which then solidify to form parts. However, it inherently induces self-equilibrating residual stress during fabrication due to thermal loads and plastic deformation. These residual stresses can cause defects such as delamination, cracking, and distortion, as well as premature failure under service conditions, necessitating mitigation. While post-treatment methods can reduce residual stresses, they are often costly and time-consuming. Therefore, tuning the fabrication process parameters presents a more feasible approach. Accordingly, in addition to providing a comprehensive view of residual stress by their classification, formation mechanisms, measurement methods, and common post-treatment, this paper reviews and compares the studies conducted on the effect of key parameters of the LAM process on the resulting residual stresses. This review focuses on proactively adjusting LAM process parameters as a strategic approach to mitigate residual stress formation. It provides a result of the various parameters influencing residual stress outcomes, such as laser power, scanning speed, beam diameter, hatch spacing, and scanning strategies. Finally, the paper identifies existing research gaps and proposes future studies needed to deepen understanding of the relationship between process parameters and residual stress mitigation in LAM.