Effect of double-side welding on the microstructural characteristics and mechanical performance of dissimilar AA6061-AA5052 aluminium alloys

Abstract

In this study, cold metal transfer (CMT) based double-side welding process was employed to weld AA5052-H32 and AA6061-T6 plates having a thickness of 6 mm. The microstructure and mechanical integrity of the weldment was examined systematically. Symmetric and defect free joint with full penetration was achieved. The multiple heating and cooling cycles during CMT welding did not affect the weldment while the microstructure comprised of columnar and equiaxed dendrites and the heat affected zone (HAZ) width was < 50 mu m at all interfaces. Precipitates such as Al3Mg2, Mg2Si, and alpha-Al(FeMn)Si were observed in the fusion zone. Intergranular Al-Si eutectic structure along with few microliquefaction cracks were noticed in the alpha-Al matrix. The maximum ten-sile properties for double-side welded joint were 214 MPa and 12.30 % with a joint efficiency of 70.68 %. Tensile specimens underwent ductile fracture in the weaker AA5052-H32 side with confined plastic deformation.