| 摘要 |
PURPOSE:To obtain a weld zone having high toughness at a low cost by using a double-shielding nozzle and using an inert gas as a primary shielding gas and a reducing gas as a secondary shielding gas. CONSTITUTION:A double-shielding nozzle 21 is used in TIG welding or MIG welding. An inert gas 24 such as Ar, He or the like is supplied to the welding point of a weld metal 2 from a primary shielding nozzle 22 and a reducing gas 25 such as H2 or the like is supplied to the circumference of the welding point from a secondary shielding nozzle 23. Then when the O2 in the atmosphere is going to enter the inside of the inert gas 24 from the nozzle 22, the O2 reacts with the H2 from the nozzle 23 in the midway and is discharged in the form of H2O. When oxygen enters the inside of the gas 24 and oxidizes the surface of the weld metal 2, the oxygen contacts with the H2 from the nozzle 23 and is reduced to H2O. |
