Friction stir welding of copper and copper alloys

Abstract

Copper, through having good thermal conductivity and a relatively high melting point, generally requires preheating treatment to maintain satisfactory penetration during arc welding, ranking as a hard-to-weld material. Like aluminium and magnesium, however, copper is basically a soft metal and can therefore be relatively easily joined by friction stir welding. Available FSW research has focused on fabrication of copper (oxygen-free copper) containment canisters for nuclear waste,^1–6 fabrication of copper backing plates for sputtering devices by FSW seal welding,^{7, 8} and some other applications,⁹ whereas FSW research on copper alloys has thus far been little documented.^{10, 11} Related research topics include studies of Al alloy to Cu alloy dissimilar joints^{12, 13} as well as – although not quite the same as friction stir welding – friction stir processing of Ni–Al bronze for casting structure modification^14–16 and friction stir processing of a Cu–Mn alloy for surface modification purposes.¹⁷