The influence of silicon content on the microstructure and corrosion behavior of Laser welding-brazed steel/aluminum joint

Abstract

Laser welding-brazing is an ideal method for connecting galvanized steel and aluminum alloys. In this paper, the influence of silicon content on the microstructure and corrosion behavior of laser welding-brazed steel/aluminum joint was studied. The results indicate that silicon content can improve the wettability and control the growth of inter-metallic compound (IMC) layer. The average thickness of IMC layer is all less than 5μm. Fe-Al-Si solid solution can be found in IMC layer. Fe₂Al₅Si_0.2 and FeAl₃Si_0.09 were found in seam with AlSi₅ filler metal. Fe₂Al₅Si_0.45 and FeAl₃Si_0.17 are found in seam with AlSi₁₂ filler metal. The results of tensile test show that with the increase of silicon content, the joint can achieve good mechanical property. Corrosion test results indicate that Zn-rich zone and IMC layer are most susceptible to corrosion in NaCl or CH₃COOH solution.