Mechanisms increasing welding efficiency during new development of double shielded TIG process

Abstract

A new welding method has been developed for the tungsten inert gas process which can both improve the weld depth/width (D/W) ratio and protect the electrode from oxidation during the welding process. The effects of the welding parameters and the Marangoni convection patterns on the weld pool shapes are discussed. Results showed that the change of welding parameters directly change the temperature distribution on the pool surface and the concentration addition of the surface active element, hence, eventually affect the pattern and strength of the Marangoni convection. For the liquid pool on stainless steel, the weld shapes depends to a large extent on the pattern and strength of the Marangoni convection. It is possible to generate a heavy oxide layer on pool surface under a relatively high oxygen content to affect the surface tension stress. The heavy oxide layer may inhibit the heat flow on the weld pool surface, and reduce the D/W ratio.