Aluminum Alloy to Steel Welding Process

摘要

A resistance spot welding method may involve spot welding a workpiece stack-up that includes a steel workpiece and an aluminum alloy workpiece that overlap one another to provide a faying interface. A pair of opposed welding electrodes are pressed against opposite sides of the workpiece stack-up with one welding electrode contacting the aluminum alloy workpiece and the other welding electrode contacting the steel workpiece. The welding electrodes are constructed so that, when an electrical current is passed between the electrodes and through the workpiece stack-up, the electrical current has a greater current density in the steel workpiece than in the aluminum alloy workpiece to thereby concentrate heat within a smaller zone in the steel workpiece. Concentrating heat within a smaller zone in the steel workpiece is believed to modify the solidification behavior of the resultant molten aluminum alloy weld pool in a desirable way.

主权项

1. A method of spot welding a steel workpiece to an aluminum alloy workpiece, the method comprising:
providing a stack-up that includes a steel workpiece and an aluminum alloy workpiece, the steel workpiece and the aluminum alloy workpiece overlapping to provide a faying interface; contacting an electrode-contacting surface of the steel workpiece with a steel welding electrode; contacting an electrode-contacting surface of the aluminum alloy workpiece with an aluminum alloy welding electrode; passing an electrical current between the steel and aluminum alloy welding electrodes and through the stack-up to initiate a molten aluminum alloy weld pool within the aluminum alloy workpiece and at the faying interface, the electrical current having a greater current density in the steel workpiece than in the aluminum alloy workpiece; and ceasing passage of the electrical current at which time a contact patch formed by the aluminum alloy welding electrode at the electrode-contacting surface of the aluminum alloy workpiece is greater in surface area than a contact patch formed by the steel welding electrode at the electrode-contacting surface of the steel workpiece, the contact patch formed by the aluminum alloy welding electrode having a surface area that is greater than the contact patch formed by the steel welding electrode by a ratio of 1.5:1 to 16:1.