Characteristic of fusion-brazed joint between 5052 aluminum alloy and zinc-coated steel by CO₂ laser

Welding between aluminum and steel has become a hot and difficult problem in the field of welding. By means of CO₂ laser welding and brushing metal powder and flux before welding,overlap fusion-brazed joint between 5052 aluminum alloy and ST04Z zinc-coated steel sheets was obtained,in which the 5052 aluminum alloy was melted but zinc-coated sheet was brazed. The microstructure in the joint and fracture features of the tensile specimen were investigated by optical microscope, scanning electron microscope (SEM) and universal testing machine. The results indicate that after brushing metal powder and flux,the laser absorption could be improved greatly,and the resultant weld appearance was sound and the zinc-coated layer was not burned. The thickness of the intermediate layer was less than 10 μm,and acicular intermetallic compounds did not diffuse into the aluminum weld. The maximum tensile strength of the joint was 208 MPa,about 95% of 5052 aluminum alloy.