采用有限元法对H13钢基体表面激光熔覆Stellite6钴基粉末的温度场进行了数值模拟。分析了不同功率、扫描速率和光斑半径对单道激光熔覆温度场分布的影响, 得出了最佳工艺参数为: 激光功率1 200 W, 扫描速率200 mm/min, 光斑半径2 mm。模拟了多道搭接温度场分布, 获得了温度梯度以及熔池边缘的冷却速率。结果表明: 多道搭接时, 前一道对后一道有着明显的预热作用; 垂直于扫描方向的温度梯度最大。采用优化的工艺参数进行了激光熔覆钴基合金实验研究, 获得了组织细小、致密且无缺陷的熔覆层。数值模拟结果与实验结果吻合较好。

Numerical simulation of the laser cladding temperature field of Stellite6 cobalt-based powder on the surface of H13 steel was simulated with finite element method. Influence of different laser power, scanning speed and radius of the laser beam spot on the distribution of the temperature field were analyzed, and the optimum process parameters were obtained: the laser power is 1 200 W, scanning speed is 200 mm/min and the laser spot radius is 2 mm. After the temperature distribution of multi-track overlapping laser cladding was simulated, the temperature gradient and cooling rate at the edge of molten pool were obtained. The results show that in multi-track overlapping laser cladding, the former track has an obvious preheating effect on the latter one. The temperature gradient perpendicular to the scanning direction is the largest, which will influence the growing status of the microstructure. Laser cladding experiment of cobalt-based alloy has been carried out with the optimized parameters, and cladding layer with fine and compact microstructure without defects has been obtained. The simulated results is well coincided with the experimental results.