Numerical simulation and solidification characteristics for laser cladding of Inconel 718

During the laser cladding process, the interaction between laser beam and materials (substrate and conveyed powder) results in melting deposition. The thermal behavior and solidification characteristics significantly influence the cladding geometry and the solidified microstructure. In this paper, a three-dimensional numerical model of heat-flow multiphysics is established to investigate the non-isothermal flow and solidification characteristics in laser cladding of Inconel 718 on a substrate. The theoretical analysis of laser-powder interaction is carried out to obtain the laser energy attenuation and temperature rise of powder particles. Based on the apparent heat capacity and the moving mesh methods, the solid-liquid phase transition and material addition are handled. Subsequently, the transient evolution of the temperature and velocity fields is discussed, meanwhile the variations of solidification characteristics (including temperature gradients (G) and solidification rates (R)) on the curved solidification front are analyzed. The results indicate that the temperature gradient and solidification rate at the top of the solidification interface, compared to that at the bottom, undergo a maximum twofold and thirtyfold decrease, respectively. Supplementary, the reliability of the model was verified by comparing the simulated cladding geometry (width and height) with the experimental measurements. The simulation is found to have a relatively good agreement with the experiments. Research in this paper is instructive for understanding the thermal behavior in the melt pool and the evolutionary laws of the solidification microstructure, while reducing the cost of cladding process optimization.