Abstract
In joining aluminum alloy to galvanized (GI) steel, the huge gap of thermophysical properties, defects by zinc from the steel surface, and formation of excessive brittle Fe-Al intermetallics (IMC) are the main factors that deteriorate the joint quality. In this study, alternating current pulse gas metal arc welding (AC pulse GMAW) was suggested as a solution with a mix of electrode positive and negative modes. A 1.2 mm thick AA5052 aluminum alloy and GI steel plates were joined using 1.2 mm diameter AA4047 filler wire. A comparative study on the joint interface was conducted varying the welding current and electrode-negative (EN) ratio to investigate the effect of different welding parameters on the growth of the Fe-Al intermetallics (IMC) layer, the effect of zinc, and the mechanical characteristics of the joints. It was confirmed that the change of polarity affects the distribution of zinc element in the joints. An increase in the EN ratio suppressed the growth of the IMC layer to 3.59 μm with decreased heat input. The maximum tensile-shear strength of the welded joints was approximately 171 MPa (78% joint efficiency) at the welding current of 50 A with 20% EN ratio.
Highlights
The purpose of the present study is to investigate the effect of the current wave form as process parameters on the formation of IMC layer and on the mechanical characteristics of the dissimilar materials joints by Alternating current (AC) pulse gas metal arc welding (GMAW)
GMAW process at welding currents of 40, 50, and 60 A with electrode negative (EN) ratios of 0, 10, and 20% are compared in Figures 4 and 5, respectively, and the corresponding dimensions are listed in and the current was increased from 40 to 60 A, the wet length was increased from 6.92 to
10.45 mm as the increased heat input increased the amount of molten aluminum filler wire, which was later deposited on the steel surface
Summary
Application of aluminum alloys to the body of the automobiles with joining to steel can be an efficient way to reduce the product weight because the alloy has one third of specific gravity compared to steel with high corrosion resistance. Joining these two materials is still challenging through the conventional arc welding process due to the sensitive and complicated phenomenon of the arc with high heat input [1,2,3,4,5,6]
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