A COMPARATIVE ANALYSIS AMONG THE WELDED Al-6061 PLATES JOINED BY FSW, MIG AND TIG WELDING METHODS

The present work deals with the assessment of tensile strength, hardness, fracture behavior and microstructural changes in welded Al -6061 plates. Based on that, the performance of three different welding techniques-friction stir welding (FSW), metal inert gas welding (MIGW) and tungsten inert gas welding (TIGW) has been compared. MIG welding has been done with a filler rod whereas no filler metal has been applied during TIG welding for comparing the results with FSW, filler-less solid-state welding. The ultimate tensile strength (UTS) of MIGW sample has been found 75% and 111% higher than that of FSW and TIGW samples respectively. Also, the elongation shown by MIG joint is nearly 50% higher than that of the other two welds. The tensile properties of two non-filler welds, i.e., FSW and TIG have been found similar. The fractography results have established the ductile behavior of all three joints. The primary phase (bright Al-grains) of the base metal zone (BM) with thin solid boundary has changed into thick dendritic shapes in the welded zone (WZ). Also, the coarse secondary phase of BM has converted into fine particles in WZ under the influence of rapid cooling. The WZ has been reported harder than HAZ in MIG and FSW plates whereas the HAZ of TIGW plate has been found harder than WZ due to the accumulation of fine equiaxed secondary phase.

Automated summary

This study compares the tensile strength, hardness, fracture behavior, and microstructural changes of welded Al-6061 plates using three different welding techniques - friction stir welding (FSW), metal inert gas welding (MIGW), and tungsten inert gas welding (TIGW). MIG welding showed a 75% and 111% higher ultimate tensile strength (UTS) compared to FSW and TIGW respectively, and had a nearly 50% higher elongation than the other two welds. The tensile properties of FSW and TIG welds without filler metal were found to be similar. Fractography results confirmed the ductile behavior of all three joints. Changes in microstructure were observed, including the transformation of the primary phase in the base metal zone (BM) into dendritic shapes in the welded zone (WZ) and the conversion of the coarse secondary phase into fine particles in WZ due to rapid cooling. The WZ was found to be harder than the heat-affected zone (HAZ) in MIG and FSW plates, while the HAZ in TIGW plates was harder than the WZ due to the accumulation of fine equiaxed secondary phase.