A joining method, etc., is provided, suitable for providing improved joining giving attention to the relation between a horn part and a joining member group. A joining machine performs joining of the joining member group (a first joining member and a second joining member). A horn part of a joining processing part applies sound vibration and/or ultrasound vibration to the joining member group via a buffer member. The horn part and the first joining member are each formed of metal. The buffer member has a greater softness than that of the metal that forms the horn part.

Disclosed in the present invention is a manufacturing method for a carbon steel and austenitic stainless-steel rolling clad plate, comprising the steps of: (1) obtaining a blank material of a carbon steel layer and a blank material of a stainless-steel layer; (2) assembling blank materials; (3) cladding and rolling; (4) cold rolling; (5) first annealing; and (6) second annealing. The carbon steel and austenitic stainless-steel rolling clad plate has two unique annealing processes, so that the clad plate has the performance advantages of the austenitic stainless-steel and the carbon steel. In addition, further disclosed in the present invention is a carbon steel and austenitic stainless-steel rolling clad plate manufactured by this method.

The method comprises applying a spot load to a joint part between a first metal material and a second metal material in a state where sites to form the joint part are superposed on each other. When a total thickness of the first metal material and the second metal material at the joint part before bonding is defined as T.sub.0 mm, the total thickness thereof after bonding is defined as T.sub.1 mm, and T.sub.0/T.sub.1=R is defined as a reduction ratio, the reduction ratio R is 1.4 or more.

A friction stir spot welding apparatus includes a pin member formed in a solid cylindrical shape, a shoulder member formed in a hollow cylindrical shape, the pin member being inserted in the shoulder member, a rotary actuator that rotates the pin member and the shoulder member on an axis that is in agreement with an axial center of the pin member, and a linear actuator that linearly moves each of the pin member and the shoulder member along the axis. A tip-end part of the shoulder member is formed in a tapered shape.

Provided is a multimaterial joint material that contributes to multimaterialization and a reduction in weight of a transport apparatus, the multimaterial joint material being configured from: a flame-retardant magnesium alloy; and a metal or alloy selected from the group consisting of aluminum alloys, titanium alloys, stainless steel, and steel. This multimaterial joint material is such that two or more layers of different types of metal materials are joined, wherein the multimaterial joint material is characterized in that: of the two or more layers of metal materials, at least one layer comprises a flame-retardant magnesium alloy, and another layer comprises a metal or alloy selected from the group consisting of aluminum alloys, titanium alloys, stainless steel, and steel; and the two or more layers of metal materials are joined together across the entire surface of joining surfaces that overlap each other.

A dissimilar material solid phase bonding method is disclosed wherein one member and another member having different compositions are brought into contact with one another by way of an insert material to form an interface (1) to be bonded, at which the one member and the insert material are in contact with one another, and an interface (2) to be bonded, at which the other member and the insert material are in contact with one another; the temperature of the interface (1) to be bonded and the interface (2) to be bonded is raised by means of frictional heat and/or by electrical heating; a bonding pressure (1) is applied substantially perpendicular to the interface (1) to be bonded; a bonding pressure (2) is applied substantially perpendicular to the interface (2) to be bonded; and the bonding pressure (1) and the bonding pressure (2) are set to different values.

Steel sheet low in cost and improved in fatigue characteristics without causing a drop in the cold formability, characterized in that it comprises an inner layer and a hard layer on one or both surfaces of the inner layer, a thickness of the hard layer is 20 μm or more and 40% or less of the thickness of the steel sheet, an average micro-Vickers hardness of the hard layer is 240 HV or more and less than 400 HV, an amount of C of the hard layer is 0.4 mass % or less, an amount of N is 0.02 mass % or less, a variation of hardness measured by a nanoindenter at a depth of 10 from the surface of the hard layer is a standard deviation of 2.0 or less, an average micro-Vickers hardness of the inner layer is 80 HV or more and less than 400 HV, a volume rate of carbides contained in the inner layer is less than 2.00%, and the average micro-Vickers hardness of the hard layer is 1.05 times or more the average micro-Vickers hardness of the inner layer.

An embodiment relates to an ultrasonic additive manufacturing process, comprising joining a foil comprising a bulk metallic glass to a substrate; and forming a cladded composite comprising the foil and the substrate; wherein a thickness of the cladded composite is greater than a critical casting thickness of the bulk metallic glass, wherein the cladded composite comprises a cladding layer of the bulk metallic glass on the substrate and the bulk metallic glass comprises approximately 0% crystallinity, approximately 0% porosity, less than 50 MPa thermal stress, approximately 0% distortion, approximately 0 inch heat affected zone, approximately 0% dilution, and a strength of about 2,000-3,500 MPa.

An embodiment relates to an ultrasonic additive manufacturing process, comprising joining a foil comprising a bulk metallic glass to a substrate; and forming a cladded composite comprising the foil and the substrate; wherein a thickness of the cladded composite is greater than a critical casting thickness of the bulk metallic glass, wherein the cladded composite comprises a cladding layer of the bulk metallic glass on the substrate and the bulk metallic glass comprises approximately 0% crystallinity, approximately 0% porosity, less than 50 MPa thermal stress, approximately 0% distortion, approximately 0 inch heat affected zone, approximately 0% dilution, and a strength of about 2,000-3,500 MPa.

A friction stir welding tool, which includes a pin and a shoulder rigidly connected to the pin, for welding components composed of a parent material having a melting point of more than 900° C., in particular steel. To achieve a particularly long service life of the tool even with thick-walled components, it is provided that the shoulder is at least partially composed of a first material and the pin is at least partially composed of a second material. Furthermore, the shoulder is at least partially composed of a first: material and the pin is at least partially composed of a second material. In addition, a method for joining components of one or more parent materials having a melting temperature of more than 900° C. is provided.