| 摘要 |
PROBLEM TO BE SOLVED: To prevent the development of spot defect by using assist gas having the blowing direction in specific range to the welding direction in the case of welding a carbon steel or an alloy steel having a specific value or more of thickness with laser beam having a specific value or more of output. SOLUTION: At the time of welding the carbon steel 1 or the alloy steel 1 having >=4.0mm thickness with the laser beam 2 having >=15KW output at >=2.0m/min welding speed, in order to prevent the development of the spot defect, the blowing direction of the assist gas 6 (helium) is made to 0-70 deg. forward or 0-10 deg. backward, i.e., (-10 deg.-70 deg.) to the welding direction (a) so that the force P does not affect to the direction which the welding metal 5 covers on a keyhole 4. Further, previous to the welding, the material 1 to be welded is preheated. |
