焊丝熔化填充方式对激光焊接熔池影响的数值模拟

结合激光深熔焊的焊接特性，建立焊丝熔化后进入熔池过程的三维瞬态激光焊接热-流耦合模型。研究了焊丝熔化填充方式对匙孔三维形态、熔池流动行为的影响，最后分析了焊丝熔化填充对匙孔稳定性的影响机制。计算结果表明，焊丝熔化以自由过渡的形式落入熔池对匙孔的形态影响较大，对匙孔前壁的挤压作用非常明显，造成了匙孔闭合、倒塌的情况；焊丝熔化沿熔池边缘流入熔池对匙孔的形态影响相对较小，匙孔下部会出现内凹的现象。焊丝熔化进入熔池之后在匙孔后方的熔池会产生两个顺时针的流动漩涡，流动漩涡的存在会使熔池内部流动行为更加复杂。

Numerical simulation of effect of filler wire melting and filling mode on molten pool in laser welding

Based on the welding characteristics of laser deep penetration welding, a three-dimensional transient thermal-flow coupling model of laser welding was established in the process when filler was melted into molten pool. The effect of filler metal filling mode on the three-dimensional shape of keyhole and the flow behavior of molten pool was studied. Finally, the influence mechanism of filler metal filling on keyhole stability was analyzed. The results show that filler metal in the form of a free transition into the molten pool had larger impact on the keyhole shape, causing the keyhole to close and collapse. The filler metal in the form of filling along the edge of the molten pool into the molten pool had relatively small impact on the keyhole shape, the keyhole bottom appeared concave phenomenon. After filler metal filled into the molten pool, two clockwise flow vortices were produced behind the keyhole wall, which made the flow behavior of the molten pool more complex.