Surface enhancement on TIG welded dissimilar Al-Mg alloy with ER5356 and scandium composites filler rod

Abstract

The effect of different process parameters on Tungsten Inert Gas (TIG) welded dissimilar aluminium magnesium alloy AA5083-H111 and AA5052-H32 by using ER5356 filler rod and scandium added ER5356 composites is investigated in this research. Extremely required in the automobile and aerospace industries, some defects like micro pores and weaken the fusion zone on the joint are identified with ER5356 filler rod. To resolve these defects, scandium added ER5356 composite filler rod is used to compose the TIG welded joints with free defects. There are three different TIG welding process parameters like Current (A), gas flow rate (L/min) and (0, 0.25 and 0.5 wt% of Scandium with ER5356 filler rod are used by Taguchi L9 method. The macrostructure, microstructure and mechanical properties of TIG welded joints are investigated on all the welded samples. To optimize the process parameter is more significant, therefore grey relational analysis used to optimize the parameters with identified mechanical properties tensile strength and micro hardness, respectively. Out of different process parameters, joint made with process parameter current at 190 A, gas flow rate 10 l min⁻¹ and 0.50% scandium added ER5356 enhances the mechanical properties (264 MPa and 119 Hv) which is maximum than other scandium free ER5356 and 0.255 scandium filler rod and enhanced strength welded sample exhibited fine grain refinement on the weld seam. Due to added scandium on the welded zones, secondary phase particles are generated during SEM examination and the optimized samples were utilized for fractography test to exhibit the ductile nature in fractured area. The EDS mapping also shows the elemental distribution on the welded zones, the scandium plays the major role as a better reinforcement to improve intermetallic strength. Finally, the grey with ANOVA also proves that the scandium added joints achieves influencing process parameters.