Numerical Simulation Study on the Motion Behavior of WC Hard Phase Particles in the Laser Cladding Process of Nickel-Based WC60 Powder

Abstract The distribution uniformity of WC hard phase particles during laser cladding of Ni-based WC60 powder critically determines the mechanical properties and wear resistance of the coating. The frequent deposition of WC particles is a primary cause of coating cracking and performance degradation, with particle size playing a decisive role in this behavior. In this study, a 3D coupled thermal‑flow‑particle multiphysics model was established to investigate the motion and deposition of WC particles of five different diameters (144, 124, 104, 84, and 64 µm). The results show that coarse particles (124 and 144 µm) are inertia-dominated, moving along a slanting downward trajectory and finally concentrating at the bottom of the molten pool with high accumulation density. Fine particles (64 and 84 µm) are drag‑dominated, horizontally transported to the pool edge by Marangoni convection, and dispersed over the upper, middle, lower and edge regions. Medium particles (104 µm) exhibit transitional behavior. The particle size effect can be quantitatively characterized by the Stokes number: as the particle size decreases, the deposition distribution gradually shifts from bottom-concentrated to edge-spread in a gradient manner. The predicted errors of the cladding layer height and width agree well with the experimental data; the simulated particle distribution trends are consistent with SEM observations. The proposed model effectively predicts the motion behavior of WC particles of different sizes, providing a theoretical basis for tailoring the spatial distribution of the reinforcing phase in laser cladding.