活性元素氧对AA-TIG焊熔池传输行为影响的数值模拟

电弧辅助活性TIG焊(arc assisted activating TIG welding,AA-TIG焊),采用辅助电弧以Ar+O₂作为保护气体预熔待焊母材表面以形成氧化层,再进行常规TIG焊,可使熔深明显增加.文中结合AA-TIG焊熔池氧元素分布的实验研究,提出焊接熔池表面氧元素的两种不均匀分布模式,考虑浮力、电磁力和表面张力,建立了更完善的电弧辅助活性TIG焊熔池模型,模拟研究氧元素在熔池表面呈不均匀分布时,AA-TIG焊瞬态熔池中动量及能量的传输行为.假设熔池内部液态金属是湍流、不可压缩Newton流体,使用FLUENT RNG k-ε湍流模型进行处理.结果表明,当氧在熔池上表面呈非均匀分布,并且氧的不均匀分布模型为低氧模型时,熔池内部仍然以内对流流动为主.

Numerical simulation of the effects of oxygen as active element on weld transportation behavior in arc assisted activating TIG welding

In arc assisted activating TIG welding process, the base metal is pre-melted by an assisting arc along with mixture of argon and oxygen to form an oxide layer. After TIG welding, the weld penetration can be increased significantly. In this paper, two modes of uneven oxygen distribution at the surface of weld pool is proposed based on the experimental measurements; buoyance. A more sophisticated model of the weld pool in AA-TIG welding is developed, taking Lorentz force and surface tension into account. This model is developed to calculate the transportation hehavior of mass, momentum and energy in AA-TIG weld pool with the uneven oxygen distribution. In this paper, surface tension is a function of the temprerature coefficent and the concentration coefficient of the surface tension.The fluid flow in the weld pool is assumed to be turbulence and incompressible Newtonian fluid. The model is based on the RNG k-ε turbulence model. The experiments show that the calculated results agree well with measured value.