Microstructural characterization and mechanical properties of dissimilar friction welding of 1060 aluminum to AZ31B magnesium alloy

Dissimilar welding of aluminum bars and magnesium bars was produced by the friction welding technique. The interfacial microstructure characteristics was evaluated after friction welding of Al-Mg alloy using optical microscopy, scanning electron microscopy, as well as X-ray diffraction analysis. Friction and forge pressure were selected as variable parameters. The friction time was maintained at 10 s for a rotational speed of 2800 rpm. The chemical compositions of the interfaces of the welded joints were determined by using energy dispersive spectroscopy. Experimental results showed that intermetallic compounds (IMCs), consisting of phase β-Al3Mg2 and γ-Al12Mg17, were generated in the interfaces of the Al and Mg alloys. When the friction and forge pressure increased the thickness of IMCs layer at the interfaces decreased as a result of more mass discarded from the welding interfaces. Heavy thickness of IMCs layer seriously deteriorated the mechanical properties of the joints. Microcracks were generated along the welded interfaces of all the welded samples. Formation of microcracks could be controlled effectively under the higher friction and forge pressure. Mechanical evaluations were conducted by determining microhardness and the tensile tests. It was observed that the tensile strength of the joints depended on the friction and forge pressure and the maximum tensile strength was 138 MPa.