A welded assembly and a method of reaction metallurgical welding are disclosed. The assembly includes a first metallic workpiece and a second metallic workpiece attached together by at least two overlapping weld joints. The overlapping weld joints are reaction metallurgically joined (RMJ) weld joints, and each overlapping weld joint overlaps with the other overlapping weld joint by 10-75%. The method of welding includes providing a reactive material between and in contact with the first and second workpieces. In a first position, the workpieces and the reactive material are pressed together, heated, and held between first and second tools to form a first RMJ weld joint between the workpieces. Then, in a second position, the workpieces are pressed together, heated, and held between the tools to form a second RMJ weld joint that overlaps with the first RMJ weld joint.

An apparatus (10) for joining a predetermined geometrical profile shape from a sheet material (SM) includes a positioning assembly (12) including a base member (14) and a frame (16) that is operable to receive the sheet material (SM), to configure the sheet material in a predetermined orientation and to linearly translate the sheet material along a process direction (20). A Z-bar (22) is configured to guide a first longitudinal edge (FE) and second longitudinal edge (SE) of the sheet material (SM) into adjacent alignment along the process direction (20). A welding and forging assembly (60) welds and then forges a seam between the first longitudinal edge (FE) and the second longitudinal edge (SE) of the associated sheet material (SM).

An ironing plate is attached to a friction stir welding apparatus in such a manner that the ironing plate surrounds an outer peripheral portion of a rotating tool and does not rotate together with the rotating tool, an inside diameter of a portion of the ironing plate into which the rotating tool is inserted is larger than the diameter of the rotating tool, and a material inflow path through which an excessive material of two metallic plates flows in is formed between the ironing plate and the rotating tool when the ironing plate is disposed to surround the outer peripheral portion of the rotating tool.

A joining apparatus for panel sheets and a joining method for panel sheets using the same are provided. The joining apparatus includes an element punching device which stores and supplies elements according to a specification of a panel sheet and inserts the element into a first panel sheet among different types of panel sheets. Additionally, a welding device resistively welds a part of the first panel sheet into which the element is inserted by the element punching device.

A joining apparatus for panel sheets and a joining method for panel sheets using the same are provided. The joining apparatus includes an element punching device which stores and supplies elements according to a specification of a panel sheet and inserts the element into a first panel sheet among different types of panel sheets. Additionally, a welding device resistively welds a part of the first panel sheet into which the element is inserted by the element punching device.

A method for manufacturing an electric resistance welded steel pipe having an identifiable seam portion. The method includes electric resistance welding a steel pipe, cutting an inner surface bead and an outer surface bead of the steel pipe in such a manner so as to cut: (i) a whole the outer surface bead and a part of the inner surface bead to leave an uncut portion in the inner surface bead, or (ii) a whole of the inner surface bead and a part of the outer surface bead to leave an uncut portion in the outer surface bead, coating the steel pipe with zinc phosphate, and cold drawing the steel pipe using a plug and a die to make the seam portion of the steel pipe identifiable.

An electric resistance welded steel pipe having an identifiable seam portion and a method for manufacturing the same. The electric resistance welded steel pipe includes a steel pipe portion with a seam portion, which is formed by electric resistance welding, and a coating portion of zinc phosphate. The coating portion covers at least an outer surface side of the steel pipe portion. A part of the coating portion that is immediately above the seam portion forms a color difference portion that has a width W along a pipe circumferential direction of greater than or equal to 0.1 times a wall thickness of the pipe and less than or equal to the wall thickness of the pipe. The color difference portion has a visually identifiable color difference from the other parts of the coating portion.

An electric-resistance-welded stainless clad steel pipe or tube that is excellent in both the fracture property of the weld and the corrosion resistance of the pipe or tube inner surface as electric resistance welded without additional welding treatment such as weld overlaying after electric resistance welding is provided. An electric-resistance-welded stainless clad steel pipe or tube comprises: an outer layer of carbon steel or low-alloy steel; and an inner layer of austenitic stainless steel having a predetermined chemical composition, wherein a flatness value h/D in a 90 flattening test in accordance with JIS G 3445 is less than 0.3, and a pipe or tube inner surface has no crack in a sulfuric acid-copper sulfate corrosion test in accordance with ASTM A262-13, Practice E, where h is a flattening crack height (mm), and D is a pipe or tube outer diameter (mm).

An apparatus (10) for joining a predetermined geometrical profile shape from a sheet material (SM) includes a positioning assembly (12) including a base member (14) and a frame (16) that is operable to receive the sheet material (SM), to configure the sheet material in a predetermined orientation and to linearly translate the sheet material along a process direction (20). A Z-bar (22) is configured to guide a first longitudinal edge (FE) and second longitudinal edge (SE) of the sheet material (SM) into adjacent alignment along the process direction (20). A welding and forging assembly (60) welds and then forges a seam between the first longitudinal edge (FE) and the second longitudinal edge (SE) of the associated sheet material (SM).

A welded state monitoring system according to an aspect of the present invention is a welded state monitoring system used for plasma shielded electric resistance welding in which electric resistance welding is performed while irradiating a weld zone of a steel sheet with plasma, and is provided with a plasma irradiation device which irradiates the weld zone with plasma, a first image capturing device which captures an image of the weld zone from above and has an image sensor capable of detecting light having a wavelength of 850 nm or more, a first wavelength region limiting device which limits light incident on the first image capturing device to a wavelength region of 850 nm or more, and an image processing device which subjects the image captured by the first image capturing device to image processing and analyzes the welded state of the weld zone thereby being able to analyze the welded state without being affected by the plasma.