Type 316LN austenitic stainless steel is widely used in the fabrication of high-temperature power plant components. High nitrogen stainless steels are desirable since they have better creep strength and good mechanical properties. Various welding processes are used in joining of 316LN stainless steel.

Among the welding processes, A-TIG welding is being considered due to single pass, autogenous process with enhanced productivity. The flux plays an important role in the penetration, microstructure and mechanical properties of weldments.

In the present study, among the welding process variables, effect of shielding gas composition on weldment properties was carried out. Shielding gas composition (%) was varied from pure argon to pure helium. The weldments were defect-free and the microstructure has equiaxed zone surrounded by columnar zones.

The helium shielded weldments have better mechanical properties than argon shielded weldments. As the helium content increases, there was an increase in heat input and penetration in A-TIG welding process. Hence there is a possible advantage in joining of high thickness plates with argon and helium mixed shielding gas than pure argon gas shielding alone.

This article is shared by B. Arivazhagan, Pavan A R and M. Vasudevan of IGCAR, Kalpakkam.