Highly efficient TIG welding of Cr13Ni5Mo martensitic stainless steel

A double-shielded TIG welding process using pure He gas as the inner shielding layer and He and CO2 mixed gas as the outer shielding layer was proposed for the welding of Cr13Ni5Mo martensitic stainless steels. This proposed welding process can successfully address the problem of electrode oxidation with mixed-gas TIG welding and the issue of low weld depth and welding efficiency of traditional TIG welding. A change in the direction of the surface tension convection mode was the primary mechanism that affected the fusion zone profile. When the oxygen content in the weld pool was in the range of 80–120 ppm, the surface tension convection direction changed from outward to inward, resulting in both a larger weld depth and a larger weld depth/width ratio. This process not only allows for a high welding efficiency comparing with traditional TIG welding but also produces better weld impact properties than those of MAG welding (metal active gas welding).