Study on the Microstructure and Mechanical Properties of Butt GMAW Al/Fe Dissimilar Joints using Pure Copper Filler Metal

Abstract

The automobile industry is required to reduce the automotive exhaust emissions and enhance fuel efficiency by reducing the weight of the vehicle body (lightweight body) and increasing the strength of the vehicle. To manufacture a lightweight body, there have been numerous studies on Al/Fe dissimilar joining globally. However, the biggest problem of those studies was the formation of the Al-Fe intermetallic compound (IMC) layer, which broke the weld metal on the Al-Fe IMC layer. Therefore, in this study, Al/Fe dissimilar joining using gas metal arc welding using pure copper (Cu) filler metal was proposed to solve the aforementioned issues. As the travel speed increased 5 to 9 mm/s, the temperature gradient and crystal cooling rate increased. This made the Al-Cu Eutectic and Hypereutectic Zone to be narrow and dendrite α-Al Zone to be wide in the Al-based weld zone (Weld Zone Ⅱ). From the travel speed of 8 mm/s, the hardness at the Weld Zone Ⅱ is lower than the under the travel of 7 mm/s. The tensile test results for fracture was observed in the Al base metal.