Modeling of Heat and Mass Transfer in the Laser-Plasma Method of Direct Powder Deposition

For the direct laser-plasma powder cladding method, the temperature distributions and surface profiles of deposited layers from a steel micro powder on the flat sample are numerically investigated. The deposition is performed using various scanning strategies of the laser system—with oscillations in a sinusoidal curve, circular, elliptical or figure-eight trajectories with constant linear motion, for both single and multi-layer beads. Numerical modeling of the problem is carried out taking into account the heat and mass transfer processes in a region containing moving curvilinear boundaries occurring during the gas-jet feed of powder particles into the melt pool created by laser-plasma action. Effective trajectories and frequencies of the periodical oscillations of the laser beam were discovered, at which the amount of cladded powder is maximal, and the resulting beads have a smooth symmetrical shape. It’s shown that this occurs due to flexible and precise control of the melt pool size and shape, when it best corresponds to the profile of the powder particles flow. As the result, the model allows determining the optimal regimes of laser-plasma cladding, ensuring the highest powder utilization coefficient and the absence of excessive substrate overheating, simultaneously.