Comparative Microstructural, Mechanical and Corrosion Study between Dissimilar ATIG and Conventional TIG Weldments of 316L Stainless Steel and Mild Steel

Stainless steels and mild steels are widespread materials in several industries. The dissimilar welding of materials is a technique used to meet the needs of various industries. Mild steel and 316L austenitic stainless steel have different chemical compositions and thermal and mechanical properties. Therefore, it would be interesting to develop a flux paste that would ensure the reliability and sustainability of welded structures made of dissimilar materials. In this work, pseudo-component fluxes were analyzed regarding the resulting weld aspects, microstructures, mechanical properties and corrosion resistance of dissimilar 316L austenitic stainless steel and mild steel welded joints. Using a mixing design available in Minitab 17 software, the obtained optimal pseudo-component flux was composed of 74% SiO2, 3% Fe2O3, 13% Cr2O3 and 10% NaF. During this investigation, the weld carried out using the optimal flux combination with the activated tungsten inert gas (ATIG) technique was evaluated and compared to another weld executed using the conventional tungsten inert gas (TIG) process. In conclusion, we observed that the optimal flux combination used in the ATIG weld had beneficial effects on the mechanical properties without degrading corrosion resistance when compared to the conventional TIG weld. Moreover, in the ATIG process, the weld depth was achieved in a single pass, while edge preparation or the addition of a filler metal was not required.