A battery module includes a plurality of battery cells each having a terminal, and a lead plate having a lead part each of which is joined to the terminal of each of the battery cells to electrically connect the battery cells to each other. The lead part includes an aluminum thin plate having aluminum purity higher than or equal to 99.0%. Surface roughness Ra of a joining surface of the lead part to the terminal is less than or equal to 10 μm. The lead part is electrically connected to the terminal by solid-phase bonding.

Described are methods for forming a friction stir weld between a steel piece and an aluminum piece, with specific examples of the steel piece and the aluminum piece being a cover and a base of an enclosure.

Method for establishing a connection between an electrical connecting element for a motor vehicle on-board network and a cable of the motor vehicle on-board network in which the cable (2) is provided with a metallic stranded conductor (4), firstly the metallic stranded conductor is mechanically compacted in such a way that a flat area is formed, whereby during the compacting, a material bond is formed between strands of the stranded conductor (4), and subsequently, the connecting element is connected to the flat region in a material bond.

The method includes a step of preparing a first member made of a first metal and a second member made of a second metal having a smaller deformation resistance than the first metal, and a step of joining the first member and the second member. The step of joining includes a step of disposing the second member in a cavity of a mold, a step of heating the first member and the second member by relatively rotating the first member with respect to the second member, while pressing the first member against the second member, without changing a positional relationship, and a step of cooling the first member and the second member with the members being in contact with each other. In the step of disposing, the second member is disposed such that a second member contact surface is surrounded by the sidewall of the cavity.

A method of joining a first component and a second component that are made of dissimilar metals. In some embodiments, the method comprises applying friction between the first component and the second component sufficient to generate a layer of quasi-liquid metal and produce shear localization within the quasi-liquid metal at a dissimilar metal interface between the first component and the second component and terminating the application of friction at a predetermined time after generation of the quasi-liquid metal. In some embodiments, the method comprises applying amorphous metal between at least a portion of the first component and the second component at a dissimilar metal interface, heating the amorphous metal to a temperature between its glass transition temperature (T.sub.g) and the lowest melting temperature of the components involved, and applying compression pressure to generate thermoplastic deformation of the amorphous metal.

A friction welding apparatus is provided, which includes a tool, a rotary driver, a linear driver, and a control device. The control device controls the linear driver and the rotary driver so that the tool is rotated while a tip-end part thereof is pressed against a to-be-joined part of a to-be-joined object to increase a temperature of the to-be-joined part at or above an A1 transformation point, the tip-end part of the tool reaches a given first position so that a softened second member sticks into a softened first member, and the tool is drawn out from the to-be-joined part while the tool is rotated.

The method for producing a metal member includes a step of preparing a first member made of a first metal and having a recessed portion formed therein, and a second member made of a second metal having a smaller deformation resistance than the first metal, and a step of joining the first member and the second member. The step of joining includes a step of increasing temperatures of the first member and the second member by relatively rotating the second member with respect to the first member while pressing the second member against the first member with at least a part of the second member being received in the recessed portion, and a step of stopping the relative rotation of the second member with respect to the first member and cooling the first member and the second member with the members being pressed against each other.

A molding method according to the present invention is a method of molding a composite material including a first member, a second member, and a reinforcement member interposed between the first member and the second member, the method including a first step of disposing the reinforcement member between the first member and the second member, and a second step of causing the first member to collide with the second member by a predetermined urging force after the reinforcement member is disposed, thus joining the first member and the second member with the reinforcement member interposed between the first member and the second member. The composite material has a thickness of 0.01 mm or more and 1 mm or less.

In a method of friction stir welding two pieces of material of greatly differing melting temperatures, provision is made that the first piece of material is overlapped by the second piece of material. The rotating pin of the friction stir welding tool provides for a butt joint welding and an overlap welding at the same time in that the pin is moved along the face side and contacts it either not at all or at most to a minimum extent. The same also applies to the planar side of the first piece of material, which is overlapped by the less stable piece of material.

A metal composite and a metal joining method that are capable of suppressing an influence on joining strength of a friction stir welded section due to a tool hole formed when a tool is extracted, in the case in which two metals are joined through friction stir welding. In an overlapping section in an axial direction in which a first shaft and a second shaft overlap in the axial direction, an inscribed section in which the first shaft and the second shaft come in contact with each other and an non-inscribed section in which the first shaft and the second shaft do not come in contact with each other are formed. In the non-inscribed section, a plate thickness of the second shaft is decreased. Then, a starting point of a friction stir welded section is formed in the inscribed section, and an endpoint is formed in the non-inscribed section.