MULTI-STEP DIRECT WELDING OF AN ALUMINUM-BASED WORKPIECE TO A STEEL WORKPIECE
First Claim
1. A method of resistance spot welding a workpiece stack-up, which includes an aluminum-based workpiece and a steel workpiece, so as to form a resistance spot weld joint between the aluminum-based workpiece and the steel workpiece, the method comprising:
- contacting a workpiece stack-up with a pair of spot welding electrodes such that the spot welding electrodes make contact with opposed sides of the workpiece stack-up, the workpiece stack-up comprising an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, and wherein the faying surfaces of the aluminum-based workpiece and the steel workpiece overlap and contact one another to provide a faying interface between the workpieces; and
controlling the passage of electrical current between the spot welding electrodes and through the aluminum-based workpiece and the steel workpiece to perform multiple stages of weld joint development that include;
growing a molten weld pool in the aluminum-based workpiece that extends from the faying interface into the aluminum-based workpiece;
allowing the molten weld pool to cool and solidify into a weld nugget that includes a weld bond area joined to the faying surface of the steel workpiece;
re-melting at least a portion of the weld nugget including at least part of the weld bond area of the weld nugget;
allowing the re-melted portion of the weld nugget to cool and solidify.
1 Assignment
0 Petitions
Accused Products
Abstract
A workpiece stack-up that includes at least a steel workpiece and an aluminum-based workpiece can be resistance spot welded by employing a multi-stage spot welding method in which the passage of electrical current is controlled to perform multiple stages of weld joint development. The multiple stages include: (1) a molten weld pool growth stage in which a molten weld pool is initiated and grown within the aluminum-based workpiece; (2) a molten weld pool solidification stage in which the molten weld pool is allowed to cool and solidify into a weld nugget that forms all or part of a weld joint; (3) a weld nugget re-melting stage in which at least a portion of the weld nugget is re-melted; and (4) a re-melted weld nugget solidification stage in which the re-melted portion of the weld nugget is allowed to cool and solidify.
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Citations
20 Claims
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1. A method of resistance spot welding a workpiece stack-up, which includes an aluminum-based workpiece and a steel workpiece, so as to form a resistance spot weld joint between the aluminum-based workpiece and the steel workpiece, the method comprising:
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contacting a workpiece stack-up with a pair of spot welding electrodes such that the spot welding electrodes make contact with opposed sides of the workpiece stack-up, the workpiece stack-up comprising an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, and wherein the faying surfaces of the aluminum-based workpiece and the steel workpiece overlap and contact one another to provide a faying interface between the workpieces; and controlling the passage of electrical current between the spot welding electrodes and through the aluminum-based workpiece and the steel workpiece to perform multiple stages of weld joint development that include; growing a molten weld pool in the aluminum-based workpiece that extends from the faying interface into the aluminum-based workpiece; allowing the molten weld pool to cool and solidify into a weld nugget that includes a weld bond area joined to the faying surface of the steel workpiece; re-melting at least a portion of the weld nugget including at least part of the weld bond area of the weld nugget; allowing the re-melted portion of the weld nugget to cool and solidify. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of resistance spot welding a workpiece stack-up, which includes an aluminum-based workpiece and a steel workpiece, so as to form a resistance spot weld joint between the aluminum-based workpiece and the steel workpiece, the method comprising:
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providing a workpiece stack-up that includes an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, and wherein the faying surfaces of the workpieces overlap and contact one another to provide a faying interface between the workpieces; passing electrical current through the aluminum-based alloy workpiece and the steel workpiece and across the faying interface for a first period of time during which a molten weld pool that extends from the faying interface into the aluminum-based workpiece is initiated and grown; allowing the molten weld pool to cool and solidify into a weld nugget by either, for a second period of time after passage of electrical current for the first period of time, passing electrical current through the workpieces at a reduced level that allows for solidification of the molten weld pool or ceasing passage of electrical current through the workpieces; and passing electrical current through the aluminum-based alloy workpiece and the steel workpiece for a third period of time, after the weld nugget has solidified during the second period of time, during which at least a portion of the weld nugget is re-melted. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A multi-stage spot welding method comprising:
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pressing a pair of spot welding electrodes against a workpiece stack-up such that the spot welding electrodes are pressed against opposed sides of the workpiece stack-up, the workpiece stack-up comprising an aluminum-based workpiece and a steel workpiece; growing a molten weld pool in the aluminum-based workpiece that extends from a faying interface of the steel workpiece and the aluminum-based workpiece into the aluminum-based workpiece; allowing the molten weld pool to solidify into a weld nugget that includes a weld bond area joined to a faying surface of the steel workpiece at the faying interface; re-melting at least a portion of the weld nugget that includes at least part of the weld bond area; and allowing the re-melted portion of the weld nugget to solidify into a re-solidified portion of the weld nugget. - View Dependent Claims (19, 20)
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Specification