A laser welding method includes a laser beam irradiation step of oscillating a laser beam and condensing the laser beam on a welding portion, and a scanning step of scanning a spot of the laser beam. In the execution of laser welding, while oscillating the laser beam, a screw portion having a dot shape in a plan view is formed in which a metal member is melted by scanning of the spot so as to circle around a predetermined position, and while the metal member in the screw portion is in a molten state, a linear portion being linear in a plan view and continuous with the screw portion is formed in which a metal member is melted by scanning of the spot so as to be separated from the screw portion.

Laser welding of a first metal substrate having a first planar surface and a second planar surface disposed opposite the first planar surface to a second metal substrate is performed by placing an end face of the second metal substrate proximate to the first planar surface. An input laser beam from a fiber laser is generated, and a beam delivery system is provided that is configured to receive the input laser beam and generate an output laser beam having a beam spot that moves in a predetermined pattern along a first and a second axes to irradiate a target area on the second planar surface such that the target area is positioned over an intersection region of the first planar surface where the end face is positioned proximate to the first planar surface.

Laser welding of a first metal substrate having a first planar surface and a second planar surface disposed opposite the first planar surface to a second metal substrate is performed by placing an end face of the second metal substrate proximate to the first planar surface. An input laser beam from a fiber laser is generated, and a beam delivery system is provided that is configured to receive the input laser beam and generate an output laser beam having a beam spot that moves in a predetermined pattern along a first and a second axes to irradiate a target area on the second planar surface such that the target area is positioned over an intersection region of the first planar surface where the end face is positioned proximate to the first planar surface.

This steel sheet is a steel sheet (100) formed by causing end surfaces of a first sheet material (111) and a second sheet material (113) to abut each other in an in-plane direction and welding the first sheet material (111) and the second sheet material (113) via a strip-shaped welded part (115), and in which a softened part (120) that is softened more than other parts in the welded part (115) is formed in at least a part of the welded part (115), and on a first end surface of the steel sheet in which an end part of the welded part (115) in a longitudinal direction is formed, a region in which the softened part (120) is not formed is provided in at least a part of the end part of the welded part (115) in the longitudinal direction, and a maximum value of a depth of the softened part (120) in a sheet thickness direction is, as a ratio to a sheet thickness of the steel sheet (100), 50% or less.

Provided is a method of manufacturing a joined member by joining a first metal member and a second metal member, the method including: melting an end portion on a joining side of the first metal member, while the first metal member is disposed adjacent to at least a portion of the second metal member, by irradiating the heat source while scanning, the heat source irradiated to the end portion on the joining side of the first metal member has a central portion and a peripheral portion located at a periphery of the central portion and having energy intensity lower than that of the central portion, and in the peripheral portion, a length in a scanning direction of the heat source is longer than a length in a direction perpendicular or substantially perpendicular to the scanning direction of the heat source.

A lap fillet weld joint and a lap fillet weld joint manufacturing method are provided. On a side of a first edge, a first metal plate is provided with a bulging portion that has an internal space of a prescribed size, and a second metal plate has a protruding portion that faces to the bulging portion and can be inserted into the bulging portion. In a state in which the protruding portion has been inserted into the bulging portion, the first metal plate and a second edge of the second metal plate are welded, and a first weld bead is formed.

Irradiation with a laser beam is performed along a welding bead, while the laser beam is aimed, as an irradiation point of the laser beam, at a contact point between a deck plate and a U-rib that is contained in a non-welded portion of a root part, from a side of the welding bead of the root part. Thereby, it is possible to remove a crack beginning at the non-welded portion of the root part generated at a joining portion between the deck plate and the U-rib of a steel floor slab, by the irradiation with the laser beam.

A method of manufacturing a terminal-attached electric wire includes: installing an electric wire including a core wire including a plurality of element wires to a terminal having a conductor coupling part having a pair of barrel pieces, the core wire being installed between the pair of barrel pieces; bending the pair of barrel pieces to cause the pair of barrel pieces to wrap around and cover the core wire in a circumferential direction to form a slit extending in an axial direction between the pair of barrel pieces, with respect to the circumferential direction; melting the element wires of the core wire by emitting laser light toward the core wire through the slit; and adhering the element wires melted with the laser light to the conductor coupling part.

To enable welding in a state in which aluminum plating in a desired welding region is removed at a desired high accuracy, a plating layer (103) in a welding region (151) and a plating layer (104) in a welding region (152) are removed using an alkaline solution to form a preprocessed aluminum plated steel sheet (101a), and a plating layer (123) in a welding region (153) and a plating layer (124) in a welding region (154) are removed using an alkaline solution to form a preprocessed aluminum plated steel sheet (121a).

To enable welding in a state in which aluminum plating in a desired welding region is removed at a desired high accuracy, a plating layer (103) in a welding region (151) and a plating layer (104) in a welding region (152) are removed using an alkaline solution to form a preprocessed aluminum plated steel sheet (101a), and a plating layer (123) in a welding region (153) and a plating layer (124) in a welding region (154) are removed using an alkaline solution to form a preprocessed aluminum plated steel sheet (121a).