Laser-assisted machining (LAM) has been proven to improve the machinability of hard-to-cut materials, by lowering cutting forces, increasing tool life and improving surface finish. Yet, not enough work has been done so far on how LAM would affect residual stresses (RS). The current study investigates the effects of LAM on RS, using finite element modelling, after dry orthogonal cutting of Inconel 718. First, the cutting process was modelled using the smoothed-particles hydrodynamics (SPH) method; secondly, an implicit Lagrangian model was used to simulate the relaxation process. Predicted LAM results were compared to conventional machining. The model was validated using previously published experimental results

Laser powder bed fusion exhibits many advantages for manufacturing complex geometries from hard to machine alloys such as IN625. However, a major drawback is the formation of high tensile residual stresses, and the complex relationship between the process parameters and the residual stresses has not been fully investigated. The current study presents multi-scale models to examine the variation of process parameters on melt pool dimensions, cyclic temperature evolutions, cooling rate, and cyclic stress generation and how they affect the stress end state. In addition, the effect of the same energy density, which is often overlooked, on the generated residual stresses is investigated. Multi-level validation is performed based on melt pool dimensions, temperature measurements with a two-color pyrometer, and finally, in-depth residual stress measurement. The results show that scan speed has the strongest effect on residual stresses, followed by laser power and hatch spacing. The results are explained in light of the non-linear temperature evolution, temperature gradient, and cooling rate during laser exposure, cooling time, and the rate during recoating time.