Investigation of Friction-Stir Welding Parameters in the Fabrication of a 2-Layer Aluminum–Copper Pipe with Monolithic Interface

In this study, the friction-stir welding process was used to fabricate a 2-layer pipe consisting of AA5086 aluminum alloy and Cu12200 pipes. The welding was done with cylindrical and conical pin tool. The effect of rotational speed and linear velocity of the tool on the microstructure, macrostructure and mechanical properties of the joints was investigated. In this study, AA5086 aluminum alloy tube was placed upon the copper tube. Macro-studies have shown that at a rotational-travel speed ratio of 5–15 rev/mm using a conical pin tool and at a rotational-travel speed ratio of less than 10 rev/mm using a cylindrical pin tool, the tunnel defect was created in the weld cross section. The heat input is a more effective factor than the strain applied during the process, on the grain size of the stir zone. The cylindrical pin tool at rotational speed 600 rpm and travel speeds of 40 and 60 mm/min results in sound weld and a 2-layer Al/Cu pipe with monolithic interface. The effective bonding thickness and the distribution of copper particles and intermetallic compounds are important factors in achieving maximum joint strength.