Process Research On Friction Stir Welding Of Cu/Al

Copper alloy, which has excellent conductive properties are widely used inelectrical power industry. Aluminum can instead of copper in some area with theadvantages of light weight, so the joint of Cu/Al has a better prospect. However,copper and aluminum are largely different in the properties of physical and chemical,so a fine joint can hardly be obtained by fusion welding. Friction stir welding(FSW),which is suitable for the welding of dissimilar materials, can effectively avoid thedefects during welding.In this paper, the7mm and2.6mm plate of LY12aluminum alloy and T2copperwere lap welded by friction stir welding. The impact of process parameters on theweld formation and the joint performance were investigated, and the cross-sectionalmorphology, microstructures, tensile strength, microhardness and electrical resistivitywere investigated. The10mm thick1060A pure aluminum plate and T2copper werewelded by friction stir welding, the joint analysis of the microstructure, phasecomposition, tensile strength, microhardness and electrical resistivity wereinvestigated. It can provide theoretical basis of the process parameters optimization.The result shows that a well joint can hardly be obtained for the welding of thickplate, in other words, a well joint can be obtained for the welding of thin plate. For thefriction stir lap welding, when the rotating speed was750r/min，welding speed was60mm/min and90mm/min, the well weld was formed and the connection of Cu/Alwas tight. The return side of the joint has a large Hook，a small Hook exist in theadvance side. There are many defects in Hook, which can be eliminated by method ofdouble-pass welding. The results of EDS, hardness and sheer test show that diffusionwidth of Cu/Al at the bottom of nugget is smaller than that of nugget and Hook.Maximum hardness values of copper and aluminum are existed in the vicinity ofinterface, which is160HV. When the rotating speed was750r/min，welding speed was90mm/min, the joint fracture along the heat-affected zone. Holes has a great effect onresistance, so the size of Hook.The subject is to research the10mm thick T2copper and1060A pure aluminum.The results show that T2copper should be plated on the advancing side and1060Apure aluminum should be placed on the retreating side, when the tool rotation speed is 950r/min, welding speed is60mm/min, it can get a good weld surface forminginternal and defect-free welded joints. The Cu was exhibited in the form of hook atthe Cu/Al interface at the joint, a sharp increase in the microhardness was shown nearto the Cu/Al interface, which fluctuation up to195HV, which was due to theformation of intermetallics Al2Cu and Al4Cu9. A thin strip of intermetallic compoundcan improve the tensile strength of joint. Tensile facture occurred in the aluminumside of the heat affected zone. The resistivity of welding zone is higher than purealuminum resistivity, and the resistivity of the joint is92.6%of that of purealuminum.