铝合金激光深熔焊熔池小孔演变行为数值模拟研究

Numerical Simulation of Pore Evolution Behavior in Laser Deep Penetration Welding of Aluminum Alloy

高功率激光深熔焊接是目前工业应用当中最理想的先进技术。本文提出了一种三维数值模拟方法,考虑了作用在熔池小孔上的表面张力、反冲压力,利用VOF追踪气液界面,利用焓–孔隙度法解决焊接过程中熔化凝固问题,考虑了热对流、热辐射、小孔自由表面的多重吸收等传热过程,采用随小孔深度变化的旋转高斯体热源来简化焊接的过程。分析了熔池小孔的演变过程以及工艺参数对小孔形貌的影响,结果表明:熔池小孔的形貌变化是反冲压力作用的结果;焊接速度对熔池小孔的深度影响不大,焊接功率越大,熔池小孔的深度越深。

High power laser deep penetration welding is the most ideal advanced technology in current indus-trial applications. In this paper, a three-dimensional numerical simulation method is proposed, which considers the surface tension and recoil pressure on the orifice of the molten pool, uses VOF to track the gas-liquid interface, uses enthalpy porosity method to solve the melting and solidifica-tion problem in the welding process, and considers heat transfer processes such as heat convection, heat radiation and multiple absorption of the orifice free surface. A rotating Gaussian heat source varying with the depth of the hole is used to simplify the welding process. The evolution process of molten pool hole and the influence of technological parameters on the morphology of molten pool hole are analyzed. The results show that the morphology change of molten pool hole is the result of recoil pressure. The welding speed has little influence on the depth of molten pool holes. The great-er the welding power, the deeper the depth of molten pool holes.