Effect of alloying elements on intermediate temperature filler metal in stepped welding of 6063 aluminum alloy

The contents of Si, Cu, Ni and RE are changed by using orthogonal test in order to study the effect of the content changes on the melting points, spreading property and shear strength of Al-Si-Cu-Ni-RE, and the microstructure of filler metal is analyzed by SEM and EDS.It is indicated that the spreading area is mainly affected by the composition of filler metal and temperature;the DSC results show that Cu has the most important influence on the melting points filler metal, which decreases sharply with the Cu content increasing, and then Ni, Si and RE come second;the black brittle phase θ(CuAl₂) and the macrosegregation flocculent phase go against the performance of joint, but the matrix phase α(Al) with face-centered cubic solid solution and the Si phase with conglobulation make the performance of joint better.