Particle floating and transfer effect in cored wire arc additive manufacturing: Formation mechanism and laser shock inhibition

Abstract

Multi-material wire arc additive manufacturing (WAAM) presents a promising approach for fabricating high-end equipment components, with cored wire arc additive manufacturing (CWAAM) attracting significant interest. However, uneven particle distribution in CWAAM impedes technological advancement, as the mechanisms of particle flotation and its suppression remain unexplored. To address this issue, a novel nickel alloy cored wire incorporating TiC particles was developed, and the mechanism of particle flotation was investigated for the first time. The results indicate that the cored wire exhibits excellent formability, with particle flotation attributed to unstable droplet transfer, particle overflow along the side seam, and density differences. Furthermore, a laser shock-assisted CWAAM method was introduced to suppress particle flotation. Laser shock generated shock waves in the molten pool, inducing significant oscillations. Shock wave propagation altered molten pool flow dynamics and particle motion, effectively suppressing particle flotation and mitigating defects. This resulted in uniform particle dispersion in the deposited layer and facilitated particle size reduction. Additionally, laser shock eliminated porosity and fusion defects caused by particle flotation. The average grain size of the deposition layer decreased by 34.5 % and 23.3 % compared to solid wire arc additive manufacturing (SWAAM) and CWAAM, respectively, with a more random grain orientation. The average microhardness reached 394.8 HV_0.3, exceeding that of the other two methods, with no significant distribution differences. Yield strength, ultimate tensile strength, and elongation increased by 7.71 %, 5.37 %, and 12.71 % in the horizontal direction, and by 18.62 %, 6.63 %, and 13.03 % in the longitudinal direction, respectively, compared to conditions without laser shock, effectively reducing performance anisotropy. This innovative laser shock-assisted CWAAM method effectively mitigates weakened reinforcement effects and defects caused by particle flotation, thereby advancing WAAM toward large-scale, multi-material, and high-performance manufacturing.