Patent ID: 8350185

Claim:
A method for laser welding, the method comprising: providing an underlying metal sheet; providing an overlying metal sheet that is positioned over a portion of the underlying metal sheet; and irradiating a weld zone with a low heat input laser beam, wherein: the weld zone includes a selected edge of the overlying metal sheet and an upper surface region of the underlying metal sheet that is adjacent to the selected edge; the laser beam is moved across the weld zone in a zigzag pattern; the laser beam is oscillated by an Nd:YAG laser oscillator; the laser beam has an output power from 3.2 kW to 3.8 kW; the zigzag pattern has a width between 4 mm and 6 mm; the zigzag pattern has a pitch that is (a) equal to or less than 1 mm and (b) constant across at least a portion of the weld zone; the laser beam is moved across the weld zone with a welding speed that is (a) from 150 mm sec −1 to 250 mm sec −1 and (b) constant across at least a portion of the weld zone; the laser beam has a fusion zone having a fusion zone width that is larger than the pitch of the zigzag pattern; and adjacent laser beam fusion zones in the zigzag pattern are partially overlapped.