By using GTAW（tungsten argon arc welding） welding method,and respectively using pure Ar and φ（Ar）98%+φ（N,2,）2% as the shielding gas,the microstructure and corrosion resistance of welded joints are investigated. The results show that the welding technology using φ（Ar）98%+φ（N,2,）2% as the austenite（γ） content shielding gas in the welded joint’s weld zone and heat affected zone is better than the one using pure Ar. The corrosion rate of the weld point with the shielding gas adding φ（N,2,）2% is 6.4 mdd（mg/dm2·d）,which meets the standards of ASTM A923 C;With the shielding gas adding φ（N,2,）2%,the weld’s pitting potential（Eb） is1179.60 mV, the potential difference（Eb-Ep） is 32.40 mV. And the pitting corrosion resistance of the welds and the repair ability of the passive film are better than those of the welds with shielding gas of pure Ar.