Abstract: There is provided a laser welding device that welds an object to be welded including two or more conductors contacting each other. The laser welding device includes: a welding laser irradiation unit that faces a first face of the object, the welding laser irradiation unit welding the object by irradiating the object with laser light; and a preheating device preheating the object. The preheating device includes a first electrode including a first contact part contacting the first face, and a second electrode including a second contact part contacting a second face of the object, the second face being on an opposite side to the first face. The preheating device heats at least part of the object by heat generated when a current flows in the object via the first electrode and the second electrode.

Abstract: A laser welding method is a laser irradiating method for irradiating with a laser beam an irradiation target surface of a welding target formed by a plurality of overlaid metal plates, and welding the plurality of metal plates, the plurality of metal plates include a first metal plate that forms the irradiation target surface, and a second metal plate, and the laser welding method includes: a first process of irradiating the irradiation target surface with the laser beam, thereby welding the plurality of metal plates, and forming a welded part; and a second process of irradiating with the laser beam a target range of the irradiation target surface including at least part of the welded part, and remelting at least the first metal plate without remelting the second metal plate among the plurality of metal plates after the first process.

Abstract: A laser welding device that welds an object to be welded including two or more members includes: a welding laser irradiation unit that faces the object, the welding laser irradiation unit welding the object by irradiating a target portion of the object with laser light; and a heating device disposed on an opposite side to the welding laser irradiation unit seen from the object, the heating device preheating the target portion by heating the target portion from the opposite side.

Abstract: A method for joining different kinds of metal materials includes: preparing a rivet, a plurality of metal members, and a first electrode and a second electrode, each having shanks and electrode portions provided at the tips of the shanks; sandwiching the rivet and the plurality of metal members between a first electrode and a second electrode; and embedding the rivet into the metal member by pressurization and energization using the first electrode and the second electrode. The preparation step includes preparing, as the first electrode and the second electrode, two electrodes that satisfy a condition in which each of electrical resistance values of the first and second electrodes is lower than or equal to a sum of an electrical resistance value of the plurality of metal members to be joined and an electrical resistance value of the rivet.

Abstract: An iron rivet including a head and a shank, an aluminum plate, an iron plate, and first and second electrodes are prepared. A sandwiching step of sandwiching the rivet, the aluminum plate, and the iron plate between the first electrode and the second electrode, a penetration step of performing pressurization and current application by the first and second electrodes so that the shank penetrates through the aluminum plate, and a forming step of performing pressurization and current application by the first and second electrodes so that a nugget is formed between the shank and the iron plate are included. In the penetration step, the pressurization and current application is performed while air is blown to a side face of the shank so that the air hits a region around a boundary between the shank and the aluminum plate.

Abstract: An iron rivet including a head and a shank, an aluminum plate, an iron plate, and first and second electrodes are prepared. A sandwiching step of sandwiching the rivet, the aluminum plate, and the iron plate between the first electrode and the second electrode, a penetration step of performing pressurization and current application by the first and second electrodes so that the shank penetrates through the aluminum plate, and a forming step of performing pressurization and current application by the first and second electrodes so that a nugget is formed between the shank and the iron plate are included. In the penetration step, the pressurization and current application is performed while air is blown to a side face of the shank so that the air hits a region around a boundary between the shank and the aluminum plate.