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根据合金熔化与凝固过程液相区、固相区和糊状区共存的特点，建立了适合于ＧＴＡ焊接熔化与凝固过程的统一模型控制方程和辅助方程，并用控制容积积分的有限差分法对其进行了数值求解。能量方程中考虑了固／液相变潜热、表面合金元素的气化、表面对流和辐射热损失， 动量方程中考虑了浮力、电磁力和Ｍａｒａｎｇｏｎｉ力驱动流。重点讨论了Ｆｅ－１８Ｃｒ－９Ｎｉ合金中表面活性元素—硫 （Ｓ） 对Ｍａｒａｎｇｏｎｉ力诱导的熔池内涡流环路和熔池形状的影响。结果表明， Ｓ质量分数较小时， 每半个熔池内存在两个相反的涡流环路， 随着Ｓ质量分数的增加向外的流体环路逐渐减弱并消失， 面向内的流体环路逐渐增强与扩大， 造成熔池深度的增加。
According to the coexistence of liquid zone, solid zone and pasty zone in the process of melting and solidification, a unified model control equation and auxiliary equation suitable for GTA welding melting and solidification process are established. The finite difference method The numerical solution was carried out. The energy equation takes into account the latent heat of solid / liquid phase transition, gasification of surface alloy elements, surface convection and radiative heat loss, and the buoyancy, electromagnetic force and Marangoni force driving flow are taken into account in the momentum equation. The effects of sulfur (S) in the Fe-18Cr-9Ni alloy on the shape of vortex loops and puddle in a molten pool induced by Marangoni force were discussed. The results show that when S mass fraction is small, there are two opposite vortex loops in every half of the melt pool. As the S mass fraction increases, the outward fluid loop gradually weakens and disappears, and the inwardly facing fluid loop gradually increases with Expand, resulting in increased depth of the pool.