Abstract: Provided is a laser lap welding method including the steps of: preparing two steel sheets, at least one of which is a galvanized steel sheet, in such a manner that the steel sheets are directly lapped one over the other with a galvanized layer of the galvanized steel sheet located as an interface of the steel sheets; and irradiating an outer surface of any one steel sheet in the lap region of the two steel sheets with a laser beam under predetermined power and speed conditions, so that an elongated hole is formed in a molten pool extending backward from a laser irradiation position at least in the steel sheet on the outer surface side. Welding of the two steel sheets is performed while venting metal vapor produced by the laser irradiation through the elongated hole backwards in a laser travelling direction and towards a laser irradiation source.

Abstract: Provided is a laser lap welding method for a galvanized steel sheet, comprising the steps of: preparing two steel sheets (11, 12), at least one of which is a galvanized steel sheet, in such a manner that the steel sheets are directly lapped one over the other with a galvanized layer of the galvanized steel sheet located as an interface of the steel sheets; and irradiating an outer surface of any one steel sheet in the lap region of the two steel sheets with a laser beam under predetermined power and speed conditions, so that an elongated hole (20) is formed in a molten pool (2) extending backward from a laser irradiation position (10) at least in the steel sheet on the outer surface side, whereby welding (3) of the two steel sheets is performed while venting metal vapor (23) produced by the laser irradiation through the elongated hole (20) backwards (R) in a laser travelling direction and towards a laser irradiation source, wherein at a starting end portion (131, 231, 331) of a welding section (103, 203, 303)

Abstract: A laser lap welding method, for a galvanized sheet, includes, irradiating a laser beam while traveling at a laser traveling speed (v) mm/sec which leads a power per volume in unit time (P/øtv) of the laser beam within a range from 0.07 to 0.11 kWsec/mm3 when the laser beam has a power (P) which is not less than 7 kW and an irradiation spot diameter (ø) which is not less than 0.4 mm and a galvanized steel sheet has a thickness (t) mm, so that an elongated hole is formed in a molten pool extending backward from a laser irradiation spot at least in the steel sheet on the outer surface side, whereby metal vapor produced by laser irradiation is vented through the elongated hole backward in a laser traveling direction and in a direction towards a laser irradiation source.