| 摘要 |
PROBLEM TO BE SOLVED: To enable a high quality weld joint to be obtained that is free from weld metal solidification crack or weld zone hardening by welding by moving a laser irradiation position at a specific speed while it is oscillated with a specific amplitude and frequency against the abutting line. SOLUTION: A laser beam L from a laser generator 1 is transmitted to a working head 21 through a beam duct 13, 15. With the laser beam emitted from the working head 21, the abutting part of a steel tube 3 is melted and welded. The steel tube is welded by moving a laser irradiation position along the abutting part of the tube at 0.5-3.0 m/sec while the position is oscillated with an amplitude of 0.5-1.0 mm and a frequency of 10-60 Hz in the abutting line direction and/or in the direction vertical to it. The steel tube is constituted, in weight %, of 0.01-0.31% C, 0.5% or less Si, 1.0-2.0% Mn, 0.03% or less P, 0.03% or less S, and the remainder Fe and inevitable impurities. |
