Numerical Investigation of Transient Marangoni Effects on Weld Pool Dynamics in Gas Tungsten Arc Welding of Stainless Steel

In this study, the fluid flow, heat transfer, and phase change occurring during the Gas Tungsten Arc (GTA) welding of stainless steel are numerically analyzed. Of all the driving forces involved during GTA welding, the Marangoni convection due to surface tension gradient is the most dominant. The amount of surfactant present in the metal strongly influences the strength, location, and direction of the Marangoni convection. Limited work has been done in the study of transient Marangoni convection behavior in the regime where a significant amount of surfactant is present, and depending on the thermal distribution in the molten metal pool, the surface tension gradient undergoes inflection, resulting in a flow reversal. The present investigation aims to address the complex relationship among the flow reversal, surfactant activity, and thermal pattern in the weld pool.