Effect of Welding Heat Input on the Intermetallic Compound Layer and Mechanical Properties in Arc Welding-brazing Dissimilar Joining of Aluminum Alloy to Galvanized Steel

The effect of weld heat input on the formation of intermetallic compound (IMCs) layer during arc welding–brazing of aluminium and steel dissimilar alloys, was investigated through both finite element method (FEM) numerical simulations and experimental measurements. The results of FEM analysis as well as welding experiments indicated that increasing weld heat input increases the thickness of IMCs layer. The thickness of IMCs layers, as calculated from FEM simulations, was approximately equal to that measured from microstructural images, in a range of 2-6 μm. The tensile strength of arc welding–brazing­ joints­ was dependent on the thickness of IMCs layer and spreading of molten weld metal on the surfaces of steel sheet. The highest mechanical strength of 120­ MPa was obtained in the optimized heat input of 420 J/mm. The presence of the Si element in the Al-5Si filler metal led to IMCs layer with the composition of Fe­(Al,­Si)­3 phase in side of the steel and­ Al­7.2Fe­1.6Si phase in side of the weld seam.