| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-electrode arc welding method capable of reducing the dissolved oxygen amount in a weld part. SOLUTION: The two-electrode arc welding method uses a welding torch, which is equipped with a wire W to be fed to a welding base material P and with a non-consumable electrode arranged concentrically so as to surround the wire W, to generate a GMA arc 6a between the wire and the welding base material P, and to generate a plasma arc 6b between the non-consumable electrode and the welding base material P. A center gas Gc is supplied so as to directly surround the GMA arc 6a, and a shielding gas Gs is concentrically supplied to the outside of the center gas Gc. The center gas Gc is an inert gas, and the shielding gas Gs is a mixture of an inert gas and a reducing gas. The composition like this enables removal of the oxygen dissolved in a molten pool Mp and reduction of the dissolved oxygen amount in a weld bead Wp, so that low-temperature toughness of the weld bead Wp is improved. COPYRIGHT: (C)2009,JPO&INPIT
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