Abstract Dissimilar materials lap joining of aluminum alloy to galvanized steel sheets was investigated with refilled friction stir spot welding (Refilled FSSW). For the lap joint between 1.0 mm thick Novelist AC 170 PX aluminum alloy and 1.2 mm thick ST06 Z galvanized steel sheets, the maximum tensile/shear fracture load is 3044 N with cross-tension fracture load of 296 N. For that between 1.5 mm thick Aleris Superlite 200 ST aluminum alloy and 1.2 mm thick ST06 Z galvanized steel sheets, the maximum tensile/shear fracture load reaches 4500 N and the maximum cross-tension fracture load is 359 N. All samples failed through the Al/steel interface during tensile/shear and cross-tension tests. The microstructure, composition, fractogragh and fracture mode of Al/steel joints were analyzed with electron probe microanalysis (EPMA), scanning electron microscope (SEM) and X-ray diffraction (XRD). Zinc and oxygen rich layer were observed in the interface on aluminum alloy side, and ZnO phase was detected on the fractured surface of both aluminum alloy and steel sides. The samples during tensile/shear test failed mainly through shear brittle fracture with features of cleavage and intergranular fracture feature. The spot weld can be distinguished as pin-refilled zone and sleeve-plunging zone due to the distribution of zinc coating.

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Refilled friction stir spot welding of aluminum alloy to galvanized steel

The Mechanical attributes and the Microstructure of distinctive 5052 aluminum alloy and 316L Stainless steel joint fabricated by resistance spot welding were studied. Influence of spot-welding method's variables on the vital functions such as shear tensile strength, diameter of nuggets and modes of failure were analyzed. The results of the experimental analysis showed that tensile shear strength increases with the increase in weld time and weld current. Increase in tensile strength could be related with the increase in nugget diameter. Fractography was done to find out the quality of joints by distinguishing different failure modes.

Gulshad Nawaz Ahmad

Papers

Material characterization of resistance spot welded aluminium alloy 5052 and stainless steel 316L joints