Fluxless joining of aluminium alloy to steel by laser irradiation method

A6061 aluminium alloy was joined with steel using Zn filler metal under laser irradiation process. The quality of joint was evaluated by the strength of a lap joint. The effects of laser power irradiation conditions such as travelling speed and defocused distance on the joint strength were investigated. The maximum joint strength was obtained at relatively medium laser travelling speed. The excess reaction between filler metal and aluminium formed thick brittle intermetallic compounds between steel and aluminium alloy. The compounds are considered to lead to the reduction in joint strength. It was found that low wetting at high travelling speed and excess reaction layer formation at low travelling speed were responsible for low joint strength. The study revealed that the relatively high joint strength between aluminium alloy and steel was obtained by laser joining method using Zn filler without the use of flux in air atmosphere.