Effects of Filler Compositions on Mechanical and Physical Properties of the Dissimilar Resistance Spot Welded between Aluminium Alloy and Carbon Steel

Abstract

The resistance spot weld (RSW) of dissimilar materials betweeen steel and aluminium is generally more complex than that of similar materials due to the extreme differences in the mechanical, physical and chemical properties of the base metals. This study proposed the use of filler material to connect the differences of their properties. Al-Alloy 5083 with thickness of 4 mm and 1.2 mm thick carbon steel SS400 were joined in lap joint types using RSW with the filler materials. The filler materials were a mixture of steel and aluminium in which weight composition variations (Fe:Al) were 90:10; 70:30; 30:70 and 90:10 in percent. The physical properties were examined based on the microstructure using optical microscope while the mechanical properties were measured with respect to the strength and hardness using Universal Testing Machine and Vickers Microhardness respectively. Results showed that weld metals with filler composition of 70:30% had highest shear-strength. The microstructure examinations showed that Microstructure of base metal and HAZ carbon steel was ferrite and perlite while that of weld metal was bainite. There were no significant differences in the microstructures and the hardness of weld metal, HAZ, and the base metal of aluminium alloy-5083 due to nonheat-treatable material.