The invention relates to projection welding of a second metal sheet above a first metal sheet (50), wherein the first metal sheet is of a non-ferrous metal or metal alloy having as main component aluminum or magnesium, wherein the first metal sheet comprises an elongate projection that locally extends above the main upper surface of the first metal sheet to come into contact with the main lower surface of the second metal sheet, wherein the projection comprises an upper surface having a convex first section (65) with a first radius (R1) that defines in its middle the top height of the upper surface with respect to the main upper surface of the first metal sheet, and a convex second section (64) with a second radius (R2) along both elongate sides that merge into the first section, wherein the first radius is larger than the second radius.

A system and method of braze resistance spot welding of an aluminum component to a galvanized steel component involve providing an aluminum-side electrode having a first tip defining a rounded shape, providing a galvanized steel-side electrode having a second tip defining a flat shape, depositing a braze filler material between the aluminum and galvanized steel components at a desired location for a spot weld, performing a pre-heat including providing a first current across the electrodes for a first period such that the braze filler melts and removes a portion of a zinc coating from the galvanized steel component, and after performing the pre-heat, performing a spot weld between the aluminum and galvanized steel components by providing a second current across the electrodes for a second period such that the aluminum melts and the galvanized steel does not melt, wherein the second current is greater than the first current.

A system and method of braze resistance spot welding of an aluminum component to a galvanized steel component involve providing an aluminum-side electrode having a first tip defining a rounded shape, providing a galvanized steel-side electrode having a second tip defining a flat shape, depositing a braze filler material between the aluminum and galvanized steel components at a desired location for a spot weld, performing a pre-heat including providing a first current across the electrodes for a first period such that the braze filler melts and removes a portion of a zinc coating from the galvanized steel component, and after performing the pre-heat, performing a spot weld between the aluminum and galvanized steel components by providing a second current across the electrodes for a second period such that the aluminum melts and the galvanized steel does not melt, wherein the second current is greater than the first current.

A lithium-ion secondary-battery case that allows bonding without weld spatter and has high strength against external force acting on the battery case, and a method for manufacturing the lithium-ion secondary-battery case are provided. Specifically, an austenitic stainless steel foil is used for a cup component (2), and a two-phase stainless steel having an austenite transformation start temperature A.sub.C1 in a temperature increase process at 650° C. to 950° C. and an austenite and ferrite two-phase temperature range of 880° C. and higher, is used for a cover component (3), and the diffusion bonding is proceeded while accompanied by grain boundary movement upon transformation of the two-phase steel from a ferrite phase into an austenite phase within a heating temperature range of 880° C. to 1080° C.

A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is ≥4√t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

A highly corrosion-resistant spot weldment can be produced at low cost without occurrence of prominent protrusions and the like on the surface. The spot weldment is joined by a nugget formed inside stacked sheet materials through bringing a pair of electrodes arranged opposite to each other into pressure contact with the stacked sheet materials from outside and energizing the stacked sheet materials from the electrodes. The nugget has a diameter that is ≥4√t (t: thickness of sheet material) and a flattening level of 3.5 to 8, which is a ratio of diameter to thickness. Both outer surface parts of the sheet materials are free from protrusions formed due to bulging of molten metal. Even when the electrodes are made of a copper alloy, the increased amount of Cu in the outer surface parts is 0.2 mass % or less with respect to the component composition before spot welding.

An electrically assisted pressure joining apparatus and an electrically assisted pressure joining method join a first metal member and a second metal member together, and includes an electrode portion, an intermediate portion including a plurality of micropores and inserted between a first metal member and a second metal member, and a pressure portion connected to the electrode portion to receive a current from the electrode portion and transfer the current to the first metal member and the second metal member to apply a pressure to the first metal member such that the first metal member and the second metal member are joined together by the intermediate portion.

A component including at least one joint, at which a joining connection to a further component is to be formed later, is provided. A joining element having a holding section is pressed into the component, and the joining element also has a functional section, by way of which at least one further function can be implemented. The holding section of the joining element is arranged in a passage hole, and the passage hole is widened in at least one edge region by an embossing. The holding section of the joining element is pressed into the passage hole and is connected to the hole wall in a force-fitting and/or form-fitting manner and engages in the embossing. A component combination of at least two components which includes such a component and a method for producing the component and the component combination are also provided.

A component including at least one joint, at which a joining connection to a further component is to be formed later, is provided. A joining element having a holding section is pressed into the component, and the joining element also has a functional section, by way of which at least one further function can be implemented. The holding section of the joining element is arranged in a passage hole, and the passage hole is widened in at least one edge region by an embossing. The holding section of the joining element is pressed into the passage hole and is connected to the hole wall in a force-fitting and/or form-fitting manner and engages in the embossing. A component combination of at least two components which includes such a component and a method for producing the component and the component combination are also provided.

A joint structure includes a first metallic material having a first projection, a second metallic material similar to and weldable to the first metallic material, and a different material having a first penetrating part and sandwiched between the first and second metallic materials, the different material being difficult to weld to the first and second metallic materials. The first projection is smaller than the first penetrating part and is spaced from the rim of the first penetrating part. The first projection is positioned in the first penetrating part and spaced from the second metallic material by a gap. The gap has a size of a predetermined percentage of the thickness of the first projection to which arc welding is applied. The first and second metallic materials are melted and joined together inside the first penetrating part to compress and fix the different material, so all three are fixed together.