Effect of Plasma Cloud Shielding on Heat and Mass Transfer Mechanism During Laser Cladding

During the laser cladding process, the temperature, flow velocity, and element concentration of the molten pool will be affected by the plasma. Quantitative analysis of the mechanism by which the plasma affects heat and mass transfer during the laser cladding process is of great significance for improving the quality of the cladding layer. In this paper, a multi-field coupled numerical model of the laser cladding process of Fe60 using an ASTM 1045 disk laser was established. In the modeling, the interaction between the plasma cloud and the laser beam (the ionization process of metal vapor absorbing photon energy and the absorption and shielding effect of the plasma on laser energy), as well as the influence of surface tension, buoyancy, and shock waves generated by the expansion of the plasma cloud on the Marangoni flow of the liquid metal, was considered. A comparative analysis was performed on the transient evolution of the temperature field, flow field, and concentration field during the laser cladding process in the presence of the plasma cloud. The results show that the ionization process of metal vapor and the shielding effect of the plasma cloud cause a decrease in laser energy and the temperature of the cladding layer. The Marangoni flow is affected by the shock waves generated by the expansion of the plasma cloud, resulting in a decrease in the flow velocity of the melt. A slight decrease in the concentration of Fe, Cr, and Ni elements and a slight increase in the concentration of C element in the cladding layer are caused by melt evaporation.