Abstract: A method of forming a casting includes providing a preform to a mold cavity. The preform is formed from one of a first metal and a second metal and defines an interface surface. A molten portion of the other of the first metal and the second metal is cast into the mold such that the molten portion proximately contacts the interface surface of the preform. An interface layer at the interface surface, a first portion defined by the mold cavity and the interface layer, and a second portion defined by the interface layer, are formed during casting. The interface layer may define a metallurgical bond between the first portion and the second portion. In the non-limiting example provided herein, the first portion is substantially comprised of aluminum and the second portion is substantially comprised of magnesium. In a non-limiting example, the casting may be configured as a vehicle wheel.

Abstract: Methods of crack avoidance during resistance spot welding are provided. The compressive stress from the spot welding is distributed across an electrode assembly having an enlarged footprint. The electrode assembly includes a conductive core and a non-conductive cover. The delivery of current through the electrode assembly is localized to the conductive core.

Abstract: A method of laser welding aluminum alloy workpieces with dual laser beams arranged in a cross-beam orientation is disclosed. The method comprises directing dual laser beams, which include a first laser beam and a second laser beam, at and along a weld seam established between the aluminum alloy workpieces together with a filler wire. The first laser beam includes a first longitudinal axis and the second laser beam includes a second longitudinal axis. When arranged in the cross-beam orientation, a plane that intersects the first longitudinal axis and the second longitudinal axis of the first and second laser beams, respectively, forms a line where it meets the aluminum alloy workpieces that is oriented transverse to the weld seam.

Abstract: A method can be used for joining workpieces using a fastener. The fastener includes a first head and a shank extending from the first head along a fastener axis. The joining method includes the following steps: (a) rotating a fastener about a fastener axis; (b) moving the fastener toward the first and second workpieces while the fastener rotates about the fastener axis such that the fastener increases the temperature in the first and second workpieces in order to soften and pierce the first and second workpieces along the fastener axis; and (c) advancing the fastener through the first and second workpieces and toward an open cavity of a die after piercing the first and second workpieces while the fastener rotates about the fastener axis such that the shank is partially disposed inside the open cavity in order to form a second head.

Abstract: A method of spot welding a workpiece stack-up that includes a steel workpiece and an adjacent aluminum alloy workpiece involves passing an electrical current through the workpieces and between opposed welding electrodes. The formation of a weld joint between the adjacent steel and aluminum alloy workpieces is aided by a cover plate that is located between the aluminum alloy workpiece that lies adjacent to the steel workpiece and the welding electrode disposed on the same side of the workpiece stack-up. The cover plate, which includes an intruding feature, affects the flow pattern and density of the electrical current that passes through the adjacent steel and aluminum alloy workpieces in a way that helps improve the strength of the weld joint.

Abstract: A method of spot welding a workpiece stack-up that includes a steel workpiece and an aluminum alloy workpiece involves passing an electrical current through the workpieces and between welding electrodes that are constructed to affect the current density of the electrical current. The welding electrodes, more specifically, are constructed to render the density of the electrical current greater in the steel workpiece than in the aluminum alloy workpiece. This difference in current densities can be accomplished by passing, at least initially, the electrical current between a weld face of the welding electrode in contact with the steel workpiece and a perimeter region of a weld face of the welding electrode in contact with the aluminum alloy workpiece.

Abstract: The corrosion resistance of formed and shaped sheet magnesium alloy articles may be improved by applying to the article a substantially crack- and pore-free ductile metal layer on at least selected surfaces and cut or sheared edges. An exemplary ductile metal may be aluminum or its alloys. Two methods of applying such a ductile metal layer are described. One method is suitable for extended areas of the magnesium alloy surface, and is applied prior to stamping the article while a second method, suitable for cut or sheared edges, is intended for application after the article is fully formed. The incorporation of both embodiments into conventional sheet metal stamping processes to form the corrosion resistant formed magnesium article is described.

Abstract: A system and method for stabilizing the molten pool in a laser welding operation by suppressing a laser-induced plume which occurs when zinc coated steels are laser welded. The plume is a result of vaporization of zinc, and the zinc vapor in the plume disturbs the molten pool and causes blowholes, spattering and porosity. The stabilization is achieved by applying a gas such as air through a nozzle to the weld area, where the gas has sufficient velocity and flow rate to blow the zinc vapor away from the molten pool. Dramatically improved weld quality results have been demonstrated. Configuration parameters which yield optimum results—including gas flow rate and velocity, and nozzle position and orientation relative to the laser impingement location on the steel—are disclosed.

Abstract: An apparatus for resistance welding with a welder includes a heat pipe including a hollow tube and a weld electrode fitted around a portion of the heat pipe. The weld electrode and heat pipe are conductively coupled to conduct heat across an inner surface of the weld electrode.

Abstract: 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.

Abstract: A method of resistance spot welding a steel workpiece and an aluminum or aluminum alloy workpiece together includes several steps. One step involves inserting a cover between the aluminum or aluminum alloy workpiece and an adjacent welding electrode. In another step, the adjacent welding electrode is pressed against cover, and another opposed welding electrode is pressed against the steel workpiece at a weld site. In yet another step, electrical current is passed between the welding electrodes, passed through the cover, and passed through the workpieces in order to initiate and grow a molten weld pool within the aluminum or aluminum alloy workpiece.

Abstract: A method of forming a bimetallic forging includes providing a blank comprising at least a first element and a second element of a first metal, and an insert of a second metal. A blank is configured such that the insert may be substantially encapsulated by a shell defined by the first element and the second element. The blank is forged to form a bimetallic forging including an outer portion defined by the shell, an inner portion defined by the insert, and an interface layer therebetween. In a non-limiting example, the first metal is substantially comprised of aluminum and the second metal is substantially comprised of magnesium. In a non-limiting example, the blank may be forged to form a vehicle wheel including an aluminum skin substantially encapsulating a magnesium inner portion, providing wheel with a high strength to weight ratio and improved corrosion performance.

Abstract: A method of resistance spot welding a steel workpiece and an aluminum or aluminum alloy (“aluminum”) workpiece together includes several steps. One step involves providing a workpiece stack-up with a steel workpiece and an aluminum workpiece. Another step involves attaching a cover over a weld face of a welding electrode. The cover is made of a metal material with an electrical resistivity that is greater than an electrical resistivity of a material of the welding electrode. Yet another step involves performing multiple individual resistance spot welds to the workpiece stack-up. The cover abuts the aluminum workpiece while the individual resistance spot welds are performed. And another step involves removing the cover from the welding electrode after the individual spot welds are performed.

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.

Abstract: Resistance spot welding of a steel workpiece to an aluminum or an aluminum alloy workpiece can be facilitated by replacing the refractory aluminum oxide-based layer(s) on at least the faying surface of the aluminum or aluminum alloy workpiece with a protective coating that is more conducive to the spot welding process. The protective coating may be a metallic coating or a metal oxide conversion coating. In a preferred embodiment, the protective coating is a coating of zinc, tin, or an oxide of titanium, zirconium, chromium, or silicon.

Abstract: One or more ductile metal inserts may be selectively incorporated into articles of limited ductility, including metal castings and molded polymers. The inserts are positioned at joint locations for joining of the article to other articles using self-piercing riveting (SPR). The inserts are of suitable ductility, thickness and strength to receive and retain self-piercing rivets and enable a strong riveted joint between the article and a second article. In an embodiment the articles are magnesium alloy castings formed by any of sand casting, die casting and semi-solid metal casting. The chemical composition of the insert may be informed by the anticipated corrosive environment of the joint and the casting temperature of the magnesium alloy. For magnesium alloy castings which may be exposed to corrosive environments, aluminum alloy inserts are preferred.

Abstract: A method of forming a casting includes providing a preform to a mold cavity. The preform is formed from one of a first metal and a second metal and defines an interface surface. A molten portion of the other of the first metal and the second metal is cast into the mold such that the molten portion proximately contacts the interface surface of the preform. An interface layer at the interface surface, a first portion defined by the mold cavity and the interface layer, and a second portion defined by the interface layer, are formed during casting. The interface layer may define a metallurgical bond between the first portion and the second portion. In the non-limiting example provided herein, the first portion is substantially comprised of aluminum and the second portion is substantially comprised of magnesium. In a non-limiting example, the casting may be configured as a vehicle wheel.

Abstract: A method of forming a casting includes providing a preform to a mold cavity. The preform is formed from one of a first metal and a second metal and defines an interface surface. A molten portion of the other of the first metal and the second metal is cast into the mold such that the molten portion proximately contacts the interface surface of the preform. An interface layer at the interface surface, a first portion defined by the mold cavity and the interface layer, and a second portion defined by the interface layer, are formed during casting. The interface layer may define a metallurgical bond between the first portion and the second portion. In the non-limiting example provided herein, the first portion is substantially comprised of aluminum and the second portion is substantially comprised of magnesium. In a non-limiting example, the casting may be configured as a vehicle wheel.

Abstract: One or more ductile metal inserts may be selectively incorporated into articles of limited ductility, including castings and molded polymers. The inserts are positioned at joint locations for joining of the article to other articles using self-piercing riveting (SPR). The inserts are of suitable ductility, thickness and strength to receive and retain self-piercing rivets and enable a strong riveted joint between the article and a second article. In an embodiment the articles are magnesium alloy castings formed by any of sand casting, die casting and semi-solid metal casting. The chemical composition of the insert may be informed by the anticipated corrosive environment of the joint and the casting temperature of the magnesium alloy. For magnesium alloy castings which may be exposed to corrosive environments, aluminum alloy inserts are preferred.

Abstract: A method of joining a first and a second work piece, such as automotive closure panels, includes supporting the work pieces on a fixture, and then joining the work pieces to one another by a first solid state weld with a vibrating roller head of a tool assembly, such as a robotically-controlled ultrasonic seam welder. Next, a flange of the second work piece is hemmed about an outer periphery of the first work piece using the same or a different roller head with the work pieces supported by the fixture. The hemmed flange is then joined to the first work piece by a second solid state weld with the vibrating roller head of the robotically-controlled ultrasonic seam welder. A system for joining a first and a second work piece is also provided.