为了对同轴激光熔覆过程中运动的金属粉末粒子的速度和温度进行理论分析,并研究各工艺参量的影响,建立了运动中金属粉末粒子的运动模型和热模型。模拟结果表明,粉嘴几何尺寸、粒子直径以及气/粉两相流初始速度是影响粒子运动行为的重要因素;粉嘴几何尺寸、激光焦点位置、激光发散角、激光功率、粒子直径以及气/粉两相流初始速度是影响粒子热行为的重要因素。在相同的工艺参量下(粉嘴出口内径r=2 mm, 粉嘴倾角α=60°, 初始气流速度v0=0.8 m/s),基于数字粒子图像测速(DPIV)技术,对316L不锈钢粉末粒子运动模型进行了实验验证。结果表明,运动理论模型是可靠的,该模型是掌握同轴激光熔覆过程中金属粉末粒子运动行为的有效工具;同时,热模型也是分析粉末粒子温度随不同参量变化的重要工具。

In order to analyze the velocity and temperature of moving metal particles in coaxial laser cladding, and to study the influence of process parameters, the movement model and thermal model of moving metal powder particle were proposed. The simulated results show that the nozzle geometric structure, particle size and initial velocity of the shield gas /powder two-phase flow are important parameters to affect movement behavior of the powder particles, and the nozzle geometric structure, position of laser beam focual point, divergent angle, laser power, particle size and initial velocity of the shield gas /powder two-phase flow are important parameters to affect thermal behavior of the powder particles. Under the same process parameters (the inner radius of nozzle exit r=2 mm, the nozzle angle α=60°, initial gas velocity v0=0.8 m/s), based on digital particle image velocimetry (DPIV), the movement model of 316L stainless steel powder particle was proved by experiment. Results show that the movement model is reliable, and it is an efficient tool to understand the movement behavior of metal powder particles in coaxial laser cladding, and the thermal model is also an important tool to analyze the temperature change of powder particles with different parameters.