INVESTIGATING TIG ARC WELDMENTS FOR AUSTENITIC STAINLESS STEEL 304 AND 304L: A MECHANICAL AND METALLURGICAL ANALYSIS

Abstract

In this study, the mechanical properties and microstructural characteristics of welded joints made from stainless steels 304 and 304L were investigated with respect to the applied TIG welding parameters, including the filler type and applied current. Two different filler electrodes (ER304 and ER309) were used, and two distinct currents (70 and 80 A) were applied during the welding process. The dissimilar metals being joined had a thickness of 2 mm. The welded joints were evaluated using X-Ray radiography examination, tensile strength testing, microhardness testing, and microstructure investigation under all proposed welding conditions. The examination results revealed that all welding passes were continuous and free of internal defects, except for the samples welded with ER309 at 70 A. The sample welded with ER304 at 80 A demonstrated the highest average maximum tensile strength (UTS) of 692 MPa, while the sample welded with ER309 at 70 A had the lowest average UTS of 670 MPa. It was observed that welding with 80 A resulted in higher mechanical properties than welding with 70 A. The microhardness of the base metal (BM), heat-affected zone (HAZ), and weld zone (WZ) was measured for all welding conditions. A dendritic structure was formed at the WZ of the welded joints, with ferrite and austenite homogeneously distributed throughout. Consequently, based on the excellent properties obtained, ER304 at 80 A is recommended for high-tech industrial applications.