激光熔覆产生的熔池温度与对流分析

由激光熔覆产生的熔池的内部存在复杂的传热与传质过程.鉴于熔池的尺度微小以至于难以对其进行实时监控，构建了一个激光熔覆数值模型，对熔池内部的温度分布与对流模式进行了仿真分析.结果表明:熔池的温度梯度非常高，且熔池底部延伸至基体的部分由于高温发生再奥氏体化.熔池内的流体流动主要由Marangoni运动驱动，且熔池内的对流形式为环形对流，最高流速达到0.1m/s.研究结果能够为熔覆层的成型过程及合金粉末在熔池内的传输过程提供理论依据.

Analysis of Molten Pool Temperatures and Convection Caused by Laser Cladding

Complicated heat and mass transfer exist inside the molten pool generated by laser cladding. Since the scale of the molten pool is so small that it is difficult to monitor it in real time， a numerical model of laser cladding was constructed， and the temperature distribution and convection mode inside the molten pool were simulated and analyzed. The results showed that the temperature gradient in the molten pool is very large， and the part of the molten pool bottom that extends to the matrix will re-austenitize due to high temperatures. The fluid flow in the molten pool is mainly driven by Marangoni movement， and the convection in the molten pool is annular convection with a maximum flow rate of 0.1m/s. The research results can provide a reliable theoretical basis for the forming process of the cladding layer and the transmission process of the alloy powder in the molten pool.