| 摘要 |
PURPOSE:To obtain a defectless weld zone having a good mechanical property without welding defect such as porosity, by supplying an inert shielding gas and performing laser welding while injecting a gas contg. active gas such as O2 into the pierced hole in a molten pool. CONSTITUTION:A laser beam 2 is irradiated from the center of a torch nozzle 1 toward a material 4 to be welded, and an inert shielding gas 3 such as Ar or He is injected from the circumference thereof. The material is welded while an additive gas 11 is supplied from the 2nd nozzle 10 of a fine hole. The nozzle 10 of a substantially small hole is used to inject the gas 11 deep into the pierced hole 6 in the molten pool. An active gas such as O2, N2, H2, CO2 or the like or a gaseous mixture of said gas and an inert gas such as Ar or He is used as the gas 11 to decrease the surface tension of weld metal 5 and to improve wettability. Thus, the molten metal 5 fills the hole 6 and prevents the generation of porosity. |
