Laser cladding is one of the material additive manufacturing processes used to produce a metallurgically bonded deposition layer. To obtain a high-quality resulting part, a deep understanding of the underlying mechanisms is required. In this article, a mathematical model is developed to simulate the coaxial laser-cladding process with powder injection, which includes laser-substrate, laser-powder, and powder-substrate interactions. The model considers most of the associated phenomena, such as melting, solidification, evaporation, evolution of the free surface, and powder injection. The fluid flow in the melt pool, which is mainly driven by Marangoni shear stress as well as particle impinging, together with the energy balances at the liquid-vapor and the solid-liquid interfaces, are investigated. Powder heating and laser power attenuation due to the powder cloud are incorporated into the model in the calculation of the temperature distribution. The influences of the powder injection on the melt pool shape, penetration, and flow pattern are predicted through the comparison for the cases with powder injection and without powder injection. Dynamic behavior of the melt pool and the formation of the clad are simulated. The effects of the process parameters on the melt pool dimension and peak temperature are further investigated based on the validated model.

Laser aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it becomes an attractive technology for part repair in small scale. However, the details of the process remain an active area for research because of the complicated interactions involved. In this study, a mathematical model was established to investigate thermal and mass transportation phenomena, which include substrate melting and solidification as well as the powder heating process. Affected by the powder injection, the melt pool surface keeps fluctuating during the process and dynamic evolution of the melt pool shape is tracked by using the level set method. Melt pool shape and energy balance at liquid–vapor and solid–liquid interfaces are taken into account in the model. A typical hole repair process based on material deposition technology is presented. The detailed process together with the temperature distribution were simulated. The simulation results of the melt pool length and peak temperature are validated for the laser deposition process through the measurements on the melt pool geometry and surface peak temperature by the complementary metal–oxide–semiconductor camera and dual-wavelength temperature sensor.

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