Cooling to control thermal stress and solidification for welding of dissimilar materials
First Claim
1. A method of resistance spot welding comprising:
- providing a workpiece stack-up that comprises an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, the faying surfaces of the aluminum-based workpiece and the steel workpiece overlapping and contacting to provide a faying interface between the workpieces, the aluminum-based workpiece and the steel workpiece each further having an opposed side surface;
contacting the opposed side surface of the aluminum-based workpiece with a spot welding electrode and contacting the opposed side surface of the steel workpiece with another spot welding electrode such that the spot welding electrodes are aligned at a spot weld site;
controlling a passage of electrical current between the spot welding electrodes and through the aluminum-based workpiece and the steel workpiece to grow a molten weld pool in the aluminum-based workpiece that extends from the faying interface into the aluminum-based workpiece; and
cooling the aluminum-based workpiece externally around the spot welding electrode in contact with the opposed side surface of the aluminum-based workpiece to drive solidification of the molten weld pool radially inwardly and to produce a weld nugget that includes a weld bond area joined to the faying surface of the steel workpiece, the cooling being controlled to reduce residual stress in the aluminum-based workpiece at the spot weld site.
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 a spot welding method in which the welding current is controlled to perform one or more stages of weld joint development. When it is desired to terminate weld current flow and to solidify a liquid weld pool into a weld nugget (of mostly aluminum-based composition), additional cooling is applied to the outer surface of the aluminum-based workpiece around the contact area of the spot welding electrode engaging the surface of the aluminum-based workpiece surface. The additional cooling is applied and controlled so as to increase the rate of solidification of the liquid aluminum-based material and to control the direction of solidification of the weld nugget to better confine impurities, and the like, originally in the melt, at the surface of the steel workpiece.
-
Citations
18 Claims
-
1. A method of resistance spot welding comprising:
-
providing a workpiece stack-up that comprises an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, the faying surfaces of the aluminum-based workpiece and the steel workpiece overlapping and contacting to provide a faying interface between the workpieces, the aluminum-based workpiece and the steel workpiece each further having an opposed side surface; contacting the opposed side surface of the aluminum-based workpiece with a spot welding electrode and contacting the opposed side surface of the steel workpiece with another spot welding electrode such that the spot welding electrodes are aligned at a spot weld site; controlling a passage of electrical current between the spot welding electrodes and through the aluminum-based workpiece and the steel workpiece to grow a molten weld pool in the aluminum-based workpiece that extends from the faying interface into the aluminum-based workpiece; and cooling the aluminum-based workpiece externally around the spot welding electrode in contact with the opposed side surface of the aluminum-based workpiece to drive solidification of the molten weld pool radially inwardly and to produce a weld nugget that includes a weld bond area joined to the faying surface of the steel workpiece, the cooling being controlled to reduce residual stress in the aluminum-based workpiece at the spot weld site. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method of resistance spot welding comprising:
-
providing a workpiece stack-up that comprises an aluminum-based workpiece and a steel workpiece, the aluminum-based workpiece having a faying surface and the steel workpiece having a faying surface, the faying surfaces of the aluminum-based workpiece and the steel workpiece overlapping and contacting to provide a faying interface between the workpieces, the aluminum-based workpiece and the steel workpiece each further having an opposed side surface; contacting the opposed side surface of the aluminum-based workpiece with a spot welding electrode and contacting the opposed side surface of the steel workpiece with another spot welding electrode such that the spot welding electrodes are aligned at a spot weld site; controlling a passage of electrical current between the spot welding electrodes and through the aluminum-based workpiece and the steel workpiece to (1) grow a molten weld pool in the aluminum-based workpiece that extends from the faying interface into the aluminum-based workpiece, (2) solidify the molten weld pool into a weld nugget, (3) remelt at least a portion of the weld nugget, and (4) resolidify the remelted portion of the weld nugget; and
,cooling the aluminum-based workpiece externally around the spot welding electrode in contact with the opposed side surface of the aluminum-based workpiece as the remelted portion of the weld nugget resolidifies. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
-
Specification