Thermal and elasto-plastic simulations of dual-laser powder bed fusion and comparative study of various scan strategies

Abstract Laser powder bed fusion involves highly localized and transient heat input, resulting in steep thermal gradients and residual stresses that may lead to distortion, cracking, and non-uniform mechanical properties. Dual-laser powder bed fusion (D-LPBF) incorporates a secondary laser to locally modulate the thermal field, offering a route to mitigate thermal stresses and improve process efficiency. We develop a multi-physics framework integrating phenomenological D-LPBF process simulation and sequential thermo-mechanical analysis. The framework simulates variations in melt pool geometry and thermal response induced by D-LPBF interactions. The thermal model is validated against experimental melt pool size data for SS316L from literature. The numerical results further suggest that D-LPBF can modify the thermal history and reduce the maximum von Mises residual stress by about 10% and the normal stress components, $$\sigma _{yy}$$ and $$\sigma _{zz}$$ , by up to 40% compared with single laser processing. We evaluate three representative scanning strategies, including fixed offset, spot-wise pulsed, and circular trajectories. Relative to the fixed-offset strategy, the spot-wise pulsed and circular trajectory approaches enhance temperature uniformity but induce stronger transient stress fluctuations due to thermally constrained reheating. These results provide insight toward optimization for D-LPBF scan strategies to balance temperature uniformity and transient stress response, while experimental validation of the predicted stress fields remains necessary.