Friction stir extrusion of thin AA 7075-T6 into low-carbon steel: Effects of low weld pitch value

Abstract

Friction stir extrusion, a derivative process of friction stir welding, forms a mechanical joint between workpieces by forging one into a prefabricated geometry within the other. Thin sheet AA7075-T651 extrusion joints were made into an O-ring dovetail channel within a low-carbon steel workpiece. The effects of low weld pitch process parameters on joint characteristics between the extruded thin sheet AA7075-T651 and low-carbon steel were observed. The weld pitch was varied from 0.02 to 0.05 mm rev⁻¹. No material mixing was observed. Tensile-shear test results were normalised by sample width. The 0.04 mm rev⁻¹ weld pitch group yielded the highest average joint strength at 493 N mm⁻¹. The weld pitch parameters reduced machine in-process forces without a large decrease in joint strength.