Argon–helium mixtures in gas tungsten arc welding of an iron workpiece are investigated using an axisymmetric computational model that includes the cathode, workpiece, and arc plasma in the computational domain. The three-gas combined diffusion coefficient method is used to treat diffusion of helium, argon, and iron vapour. Calculations for argon–helium mixtures without metal vapour are performed; good agreement with previous numerical results is found. A transition from a helium-like to an argon-like arc occurs when the argon mole fraction increases above about 0.3. Calculations for a wide range of argon–helium mixtures including iron vapour are then performed. Adding helium to argon alters the arc properties and affects the weld geometry. Iron vapour cools the arc for all argon–helium mixtures. Iron vapour is present above the workpiece, near the cathode and in the arc fringes for very low argon mole fractions. As the argon mole fraction increases, the iron vapour becomes increasingly confined to the region above the workpiece, with small amounts near the cathode tip. Emission spectroscopy measurements of arcs in argon–helium mixtures with water-cooled copper and uncooled iron workpieces were performed. The measured distributions of atomic helium and iron emission show good agreement with the predictions of the model.

使用轴对称计算模型研究了铁工件的气体钨极电弧焊中的氩氦混合物，该模型在计算域中包括阴极，工件和电弧等离子体。三气体组合扩散系数法用于处理氦，氩和铁蒸气的扩散。进行不含金属蒸气的氩氦混合物的计算。发现与先前的数值结果吻合良好。当氩气摩尔分数增加到约0.3以上时，发生从氦样到氩气的过渡。然后进行包括铁蒸气在内的各种氩氦混合物的计算。向氩气中添加氦气会改变电弧性能并影响焊缝几何形状。铁蒸气会冷却所有氩氦混合物的电弧。铁蒸气存在于工件上方，阴极附近和电弧边缘处的氩气摩尔分数非常低。随着氩气摩尔分数的增加，铁蒸气变得越来越局限在工件上方的区域，而在阴极尖端附近的逸出量却很少。用水冷铜和未冷铁工件对氩氦混合物中的电弧进行发射光谱测量。测得的原子氦和铁的发射分布与模型的预测结果吻合良好。