US 2020/0139481 A1Published application

High aspect ratio weld face design for dissimilar metal welding

AssigneeGM Global Technology Operations LLC

InventorsAmberlee S. Haselhuhn, David R. Sigler

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Abstract

An electrical resistance spot welding electrode is disclosed for contact with a narrow or other selected spot weld region in a steel workpiece in a stack-up with an aluminum alloy workpiece for use in a spot welding method in which the weld nugget is carefully formed in the aluminum workpiece at the interface of the stack-up. The welding face of the welding electrode for contact with the steel workpiece is shaped with an aspect ratio greater than one, which fits against the contact surface of the steel workpiece, while the welding face for the aluminum-contacting weld electrode is circular (with an aspect ratio equal to one). The stack-up of workpieces may include a single steel workpiece facing two aluminum workpieces in a sandwich type stack-up or two steel workpieces facing a single aluminum workpiece with the outer steel workpiece having the narrow contact surface for the steel welding electrode.

Claims20

Dependent claims

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, the steel welding electrode having a shaped welding face with an aspect ratio greater than 1.5;
simultaneously contacting an electrode-contacting surface of the aluminum alloy workpiece with an aluminum alloy welding electrode, the aluminum alloy welding electrode having a circular-shaped welding face with an aspect ratio substantially equal to one;
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.

3 more elements

Dependencies are inferred from the claim text.