Development of a novel autogenous double pulse tungsten inert gas welding technique for joining IN625 in concentrated solar power plants

Abstract

The research focuses on the challenges of joining the IN625 alloy for high-temperature applications. Tungsten inert gas (TIG) welding has drawbacks such as higher heat input (HI), which causes elemental segregation and secondary phases, ultimately affecting the quality of weldments. Previous literature indicates that single-pulsed TIG (SP-TIG) welding has shown improvements over TIG welding. In this study, a new technique called double-pulsed TIG (DP-TIG) welding was developed to address the HI and elemental segregation issues during the welding process. The study also compares the improvements in properties of DP-TIG with SP-TIG welding. The results demonstrate that DP-TIG significantly reduces HI by 53% compared to SP-TIG. It effectively decreased residual stress by 26% and suppressed secondary phase formation. Moreover, DP-TIG exhibits superior mechanical properties, with an 11% increase in hardness and a 10% increase in tensile strength compared to SP-TIG. These findings establish DP-TIG as the preferred method for joining the IN625 alloy.