Optimization of Weld-bonding Process Conditions of Dissimilar Materials using Delta Spot Welding

In the automobile industry, studies have been made on spot welds of non-ferrous metals such as aluminum, which has lightweight, high-strength, and excellent impact properties, in order to improve fuel efficiency through lightening of vehicle body weight. However, these dissimilar welds cause intermetallic compound formation and the galvanic corrosion in corrosion environments at the weld interface. On the other hand, it is known that the weld bonding process has the property of improving strength of spot welds by applying a structural adhesive between two metals and increasing the surface adhesive force.In this study, Al 6061-T6 with a thickness of 1mm and galvanized steel sheet (GA) with a grade of 440 MPa were used as target materials. As a process method, delta spot welding equipment was used for reducing the heat input using a special process tape and the weld bonding process by the D type structural adhesive was done. As a result, tensile shear strength after salt spray test for 1920 hours was more than twice that of spot welding condition and it was confirmed that the corrosion amount of the welds was lowered. Key words: GA440, Al6061-T6, Shearing stress, Weld nugget, Resistance spot welding, Delta-spot welding, Weld-bonding process