Research on the Melt Pool Shape Formation Mechanism of the Laser Surface Remelting of Nickel-Based Single-Crystal Superalloy

By numerical simulation and experimental analysis, the melt pool shapes for the laser surface remelting of nickel-based single-crystal superalloy under different processing parameters are investigated. The results show that heat conduction and heat convection work together to determine the formation of the melt pool during the laser surface remelting, and the melt pool shape can be controlled by adjusting the laser power and laser scanning speed. For processing with large laser power and low scanning speed, the alloy vaporizes in the melt pool, which makes the melt pool shape unstable. For laser surface remelting with smaller laser power or higher scanning speed, one can have a stable "?" shape melt pool, which is because the Peclet number is large, and the heat convection plays the dominant role. For the condition with further smaller laser power or higher scanning speed, the Peclet number in the melt pool is much lower, and the heat convection is the weakest, which produces the semi-elliptical melt pool shape that has no essential difference from that of the pure heat conduction model. The present study offers theoretical support to our previous research and the future parameters selection of processing parameters for the laser repairing of nickel-based single-crystal superalloys.