Ar-N₂ガスシールド溶接における銅溶接金属の気孔生成および組織におよぼす窒素ならびにチタンの影響

抄録

OFHC copper plates were welded with Cu and Cu-Ti electrode wires using Ar-N₂ gas shielding. The effects of welding conditions, N₂% in the shielding gas and titanium content of the electrode wire on the porosity and the microstructure of the weld metal were systematically examined. The results are as follows:
(1) Using copper electrode wire, the weld metal shows better surface appearance, less porosity and deeper penetration with increase of the welding current.
(2) As N₂% in the shielding gas increases, the porosity of the weld metal increases. However, the tendency becomes very slight in the case of using Cu-Ti electrode wire.
(3) The nitrogen content of the weld metal increases with N₂% in the shielding gas. This tendency becomes more remarkable with increase of the titanium content of the electrode wire.
(4) Using Cu-Ti electrode wire, a secondary phase is observed in the weld metal. The fractional area of the secondary phase in the weld metal increases with N₂% in the shielding gas and titanium content of the electrode wire.
(5) The electron diffraction patterns of the secondary phase are in good agreement with those of TiN.
(6) The temperature of molten copper pool was measured and the formation of TiN was discussed by using thermodynamic data.