A method of resistance spot welding a stacked assembly of dissimilar workpieces. The stack assembly includes a first workpiece formed of a first alloy, a second workpiece formed of a second alloy, and a third workpiece formed of a third alloy sandwiched between the first workpiece and the second workpiece. The third alloy includes a lower resistivity than the first alloy and a lower resistivity than the second alloy. A faying interface is defined by a portion of the first workpiece in direct contact with a portion of the second workpiece through the third workpiece. A weld nugget, a braze, or a combination of a weld nugget and a braze joins the first workpiece to the second workpiece at the faying interface. An annular ring of re-solidified molten pool of third alloy surrounds the faying interface and a region of re-solidified partially melted third alloy surrounding the annular ring.

A method of resistance spot welding a stacked assembly of dissimilar workpieces. The stack assembly includes a first workpiece formed of a first alloy, a second workpiece formed of a second alloy, and a third workpiece formed of a third alloy sandwiched between the first workpiece and the second workpiece. The third alloy includes a lower resistivity than the first alloy and a lower resistivity than the second alloy. A faying interface is defined by a portion of the first workpiece in direct contact with a portion of the second workpiece through the third workpiece. A weld nugget, a braze, or a combination of a weld nugget and a braze joins the first workpiece to the second workpiece at the faying interface. An annular ring of re-solidified molten pool of third alloy surrounds the faying interface and a region of re-solidified partially melted third alloy surrounding the annular ring.

A coupling device couples, using a coupling member, a first plate of a first metal to a second plate of a second metal. A power source is connected to first and second electrodes. A driver moves the first and second electrodes relative to the coupling member and the first and second plates. A controller controls the power source and the driver to electrify the coupling member and the first and second plates under pressure. The coupling member includes a third metal approximately identical to the second metal. The first metal has a melting point lower than melting points of the second and third metals. The coupling member includes a pilot portion that is located about a center of a flat surface of a body of the coupling member and that protrudes in an extending direction. The flat surface has discharge grooves radially extending from the pilot portion.

A coupling device couples, using a coupling member, a first plate of a first metal to a second plate of a second metal. A power source is connected to first and second electrodes. A driver moves the first and second electrodes relative to the coupling member and the first and second plates. A controller controls the power source and the driver to electrify the coupling member and the first and second plates under pressure. The coupling member includes a third metal approximately identical to the second metal. The first metal has a melting point lower than melting points of the second and third metals. The coupling member includes a pilot portion that is located about a center of a flat surface of a body of the coupling member and that protrudes in an extending direction. The flat surface has discharge grooves radially extending from the pilot portion.

Welded assemblies and related methods of making the welded assemblies include a first component of a first metal material, a second component of a second metal material that is different from the first metal material, and a transition material including one or more of a high entropy alloy, a pure element, and an alloy that is not a high entropy alloy, and that is arranged between and contacting the first component and the second component. An ultrasonic weld joins the transition material to the first component, and a fusion weld joins the first component to the second component. The fusion weld contact the first component, the second component, and the transition material. The amount or level of one or more of galvanic corrosion, intermetallic compounds, and solidification cracking in the fusion weld is less than if the first component was fusion welded directly to the second component.

Welded assemblies and related methods of making the welded assemblies include a first component of a first metal material, a second component of a second metal material that is different from the first metal material, and a transition material including one or more of a high entropy alloy, a pure element, and an alloy that is not a high entropy alloy, and that is arranged between and contacting the first component and the second component. An ultrasonic weld joins the transition material to the first component, and a fusion weld joins the first component to the second component. The fusion weld contact the first component, the second component, and the transition material. The amount or level of one or more of galvanic corrosion, intermetallic compounds, and solidification cracking in the fusion weld is less than if the first component was fusion welded directly to the second component.

A method to join three panels together for a motor vehicle includes one or more of the following: layering the three panels, the three panels including a first panel, a second panel, and a third panel, the second panel being positioned between the first panel and the third panel, the third panel having a higher electrical conductivity than the first panel and the second panel; joining the first panel and the second panel together; and joining the third panel to the first panel and the second panel.

A method to join three panels together for a motor vehicle includes one or more of the following: layering the three panels, the three panels including a first panel, a second panel, and a third panel, the second panel being positioned between the first panel and the third panel, the third panel having a higher electrical conductivity than the first panel and the second panel; joining the first panel and the second panel together; and joining the third panel to the first panel and the second panel.

A coupling device is configured to, using a coupling member, couple a first plate made of a first metal and a second plate made of a second metal to each other, and includes a first electrode, a second electrode, a power source, a driver, and a controller. The power source is connected to the first electrode and the second electrode. The driver is configured to move the first electrode and the second electrode relative to the coupling member, the first plate, and the second plate. The controller is configured to control the power source and the driver to electrify the coupling member, the first plate, and the second plate while controlling the first electrode and the second electrode to apply pressure to the coupling member, the first plate, and the second plate.

A coupling device is configured to, using a coupling member, couple a first plate made of a first metal and a second plate made of a second metal to each other, and includes a first electrode, a second electrode, a power source, a driver, and a controller. The power source is connected to the first electrode and the second electrode. The driver is configured to move the first electrode and the second electrode relative to the coupling member, the first plate, and the second plate. The controller is configured to control the power source and the driver to electrify the coupling member, the first plate, and the second plate while controlling the first electrode and the second electrode to apply pressure to the coupling member, the first plate, and the second plate.