Multi-physics simulation of wobbling laser melting injection of aluminum alloy with SiC particles: SiC particles gradient distribution in fusion zone

Abstract

Laser melting injection (LMI) with SiC particles can strengthen fusion zone of metal alloy. How to improve the distribution uniformity of SiC particles are critical. In this work, a novel process of wobbling laser melting injection (WLMI) is proposed to suppress the gradient distribution of SiC particles in fusion zone of aluminum alloy. Moreover, a multiphase flow model by bi-directionally coupling the discrete element method and computational fluid dynamics is developed to simulate this WLMI process. The exchanges of both momentum and energy between particles and liquid are incorporated. It is the first time that the dynamic behaviors of both the liquid and particles during melting-solidification process under WLMI are reproduced in computational modeling. Both experimental and simulated results indicate that the distribution uniformity degree of SiC particles under WLMI, along depth and width directions, improves significantly compared with LMI. Physical mechanisms accounted for this phenomenon can be more thoroughly understood by the model. Firstly, the wobbling laser can increase the keyhole opening area, and decrease the distance between keyhole and molten pool bottoms, leading to a greater possibility that particles are captured by the liquid-solid interface in the bottom. Secondly, the reflected wobbling laser rays distributed unevenly on keyhole wall and the impact on melt surface caused by injected particles will produce downward drag forces, making the particles float to the center or the middle of molten pool.