Study on microstructure and mechanical properties of 304 stainless steel joints by TIG-MIG hybrid welding

Abstract

Abstract: Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion, and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a TIG-MIG hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using the current of 190A, and a hybrid TIG-MIG welding with currents of 190/170A respectively. The MIG, TIG, and hybrid TIG-MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created towards the transition zone and the HAZ. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG weld and hybrid TIG-MIG welds. A TIG-MIG hybrid weld of specimen welded at the currents of 190/170A has the highest UTS value and percentage elongation of 397.72 MPa and 35.7 %. The TIG-MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry