在静态磁场辅助激光加工过程中,熔池内部流场、热场等实验测定比较困难,因此采用数值模拟方法计算相关参量场完整信息。以固液多相统一模型为基础,同时考虑激光熔池内部固液相变、传热与流动、表面张力、热浮力以及洛仑兹力,研究静态磁场对电磁-激光复合熔凝过程中流场的控制机理。通过COMSOL Multiphysics软件对上述物理过程的控制方程及边界条件进行耦合求解,模拟磁场强度在0.0～0.6 T范围内熔池速度场、温度场演变规律。模拟结果显示,静态磁场对速度场具有抑制作用,但对温度场影响较小。最后以316不锈钢为基体进行验证实验,对比试样表面温度随时间变化曲线,证实计算结果与实验结果吻合度较好,表明该数学模型具有一定精度,能为电磁复合激光加工工艺提供指导。

In the process of static magnetic field assisted laser machining, the flow field and thermal field of molten pool is difficult to be measured, therefore the numerical simulation method was used to calculate complete information of relevant parameters. A solid-liquid multiphase untied model was developed, including the solid-liquid phase transition, heat transfer, surface tension, thermal buoyancy and Lorentz force. The mechanism of laser melting which was regulated by static magnetic field was studied. The above mentioned physical processes coupled equations with boundary conditions were successfully solved by the finite element differential equation solver COMSOL Multiphysics. The distribution of the velocity field and temperature field were simulated with the magnetic field strength from 0.0 T to 0.6 T. The result showed that the velocity field was significantly inhibited by the magnetic field but it had a little effect on the temperature field. Finally, the simulation was confirmed by experiment with 316 stainless and results of sample surface temperature had a good agreement with experiment data. It indicated that the mathematical model had a certain precision and could provide guidance for the electromagnetic complex laser processing technology.