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利用稳态磁场辅助激光熔凝,在不改变激光工艺参数的条件下,抑制了熔凝层表面的波纹。同时,建立了考虑熔池内部的传热、对流、相变、电磁力和熔池表面形貌的多物理场耦合仿真模型。通过对比实验结果讨论了在稳态磁场作用下,熔凝层熔池内部温度场和流场的变化规律以及表面波纹的抑制原理。结果显示,稳态磁场所提供的洛伦兹力为抑制熔池对流的阻力,其方向与熔池对流方向时刻相反。随着磁场强度的增加,熔池内部的整体流速逐渐降低,但温度场的变化不甚明显。当稳态磁场的强度大于0.5 T时,熔池形状发生变化,熔凝层表面的波纹高度明显降低,但金相组织基本不变。
The use of steady-state magnetic field assisted laser melting, without changing the laser process parameters, inhibited the surface of the melt layer ripples. At the same time, a multi-physics coupled simulation model considering the heat transfer, convection, phase transition, electromagnetic force and the surface morphology of the weld pool was established. By comparing the experimental results, the variation rules of the temperature field and the flow field inside the melt pool under the steady state magnetic field and the suppression principle of the surface corrugation are discussed. The results show that the Lorentz force provided by the steady state magnetic field is to suppress the convection resistance of the weld pool, and its direction is opposite to that of the convection direction of the weld pool. With the increase of magnetic field intensity, the overall flow rate inside the weld pool decreases gradually, but the change of temperature field is not obvious. When the steady state magnetic field intensity is greater than 0.5 T, the shape of the weld pool changes, and the corrugation height on the surface of the melt layer decreases obviously, but the microstructure is basically unchanged.