New aspects of solid-state welding in the aluminium accumulative roll bonding

Abstract

The phenomena in solid-state welding (SSW) of metals during accumulative roll bonding (ARB) are analysed. The basic mechanism in SSW is described by the ‘film theory’, where superficial oxide layers/cover layers of metals fracture when submitted to elongations, the material on both sides of the sheets to be joined are extruded through these fractures and opposing virgin surfaces touch and weld. Present results reveal new aspects of these phenomena: the presence of ‘mountain ridges’ on delaminated surfaces after ARB, bonding regions along the rolling direction and the flattening of the geometric characteristics of delaminated surfaces as the number of ARB passes rises. A model is proposed for the development of the bonds along the rolling direction.