填材对激光焊接匙孔与熔池三维瞬态行为的影响

Effect of Filler Metal on Three-Dimensional Transient Behavior of Keyholes and Molten Pools in Laser Welding

建立了填材送入过程的三维瞬态激光焊接热-流耦合模型与组合热源模型,在模型中引入了反冲压力、表面张力、热浮力、重力等焊接驱动力。采用流体体积方法追踪匙孔的气-液界面,研究了填材对匙孔三维形态和熔池流动行为的影响。研究结果表明,在激光填丝焊中,填材不利于维持匙孔的稳定性,容易出现匙孔底部闭合的情况;在激光自熔焊过程中,匙孔壁面呈现由内向外和由下向上的流动趋势,这有利于匙孔的稳定张开。

The three-dimensional transient laser welding heat-flow coupling model for the filler metal feeding process and the combined heat source model are established, in which the welding driving forces, such as recoil pressure, surface tension, thermal buoyancy and gravity, are introduced. The volume-of-fluid method is used to track the gas-liquid interfaces of keyholes, and the effect of filler metal on the three-dimensional shape of keyholes and the flow behavior of molten pools is studied. The influence mechanism of the filler metal filling on the keyhole stability is analyzed. The research results show that the filler metal filling is unfavorable to the stability of keyholes and the keyhole bottom is prone to close. In the autogenous laser welding process, a flow from inside to outside and from bottom to top appears on the keyhole walls, which is favorable to the stable opening of keyholes.