The study of mechanical strength for fusion-brazed butt joint between aluminum alloy and galvanized steel by arc-assisted laser welding

Abstract By the method of arc-assisted laser brazing with preset filler powder, the dissimilar metals butt welding experiment between 5A06 aluminum alloy and galvanized steel was conducted. The intermetallic compounds (IMCs) thickness was observed by scanning electron microscope (SEM), the spreading width was measured by micrometer and the tensile strength (TS) was tested by the tensile test machine. The effects of laser power, arc current, welding speed and the distance of heat sources on TS were investigated. The results show that the IMCs thickness increases with the increase of laser power, arc current, welding speed and the decrease of the distance of two heat sources. The assisted arc can improve spreading width with a low heat input. The TS is not only related to the IMCs thickness, but also related to the spreading width, the TS can be enhanced by improving the spreading width of aluminum liquid on steel side based on the IMCs thickness is less than 10 μm. The solder joint with good mechanical property can be obtained, and it’s IMCs thickness can be controlled in the range of 10 μm by using the optimum laser power, arc current, welding speed and the distance of heat sources that is 1.2 kW, 15 A, 10 mm/s, 15 mm, respectively. The maximum TS of joint is up to 163 MPa and the IMCs thickness of which is 8.7 μm.