Activated flux TIG welding of dissimilar SS202 and SS304 alloys: Effect of oxide and chloride fluxes on microstructure and mechanical properties of joints

Abstract Low depth of penetration limits the use of favored tungsten inert gas (TIG) welding process for joining of ferrous and non-ferrous metals, demanding weld bead profile of high quality. This article aims to study the effect of chloride and oxide fluxes viz. calcium chloride (CaCl2) and ferric oxide (Fe2O3) on micro-structural and mechanical properties of TIG welded joints of dissimilar SS304 and SS202 steels. Results reflected that use of oxide and chloride fluxes significantly affects the weld bead geometry, bead dimensions and penetration. The use of oxide flux resulted in complete penetration and approximately linear root of weld with good fusion of both the base metals. Fusion zone showed columnar dendritic cast grain structure while coarse grain structure was obtained in heat-affected zone. Fusion zone hardness was higher than SS304 base metal and an opposite trend observed for SS202 irrespective of welding condition. Fine grained heat affected zone hardness was higher than coarse rain for all welding conditions.