An Experimental study of joining aluminum to galvanized and plain carbon steels using the welding-brazing hybrid method

Today, the demand for joining dissimilar metals of aluminium and steel to reduce the vehicle weight in the automotive, aerospace and shipbuilding industries has witnessed a rapid growth. In the present study, 5083 aluminium alloy was joined to galvanized steel and plain carbon steel with 4043 and 4047 filler metals by using the welding-brazing hybrid method. The brittle intermetallic compound (IMCs) layer formed in the interface of steel-weld seam was found to have a significant influence on the joint strength. The results also indicated that increasing heat input enhanced the thickness of IMCs layer. The thickness of IMCs layers, as measured from microstructural images, was in a range of 2-6 μm. Further, the results obtained from microstructural observation showed that with equal weld heat input, the thickness of IMCs layer for the joint produced with 4047 filler metal was approximately half of that obtained for the joint produced with 4043 filler metal. The highest mechanical resistance (of about 170 MPa) was obtained for aluminum to galvanized steel joint with 4047 filler metal. Moreover, in this joint, the failures occurred in the welded seam and for aluminum to plain carbon steel joint, it was in the interface of steel‌-‌weld seam.‌ The results obtained by Energy dispersive x-ray spectrometry analysis of IMCs layer for aluminum to galvanized steel joint showed the presence of the FeAl3 intermetallic compound. This was confirmed by x-ray diffraction analysis of the fracture plane.