meter ranges. Similar welding parameters for duplex stainless
steel pipes were obtained in the work of Huismann and
Hoffmeister [8] with welding speed of 4 mm/s and pulse
currents of 250±350 A.
3.3. Microstructure
Metallographic examination and nitrogen content determination
were done with acceptable weld beads obtained
from welding with the parameters shown in Table 3.
The amount of nitrogen in the weld metal at various
nitrogen contents in the argon shielding gas is shown in
Fig. 9. Pure argon shielding gas in this TIG pulse welding
did not totally shield the weld pool from air. A higher
nitrogen content in weld metal welding with pure argon
shielding gas than the content in the base metal was
observed. The weld metal nitrogen content increased from
0.06 to 0.15 wt% as the nitrogen content in the argon
shielding gas was increased from 0 to 5% (v/v.). (Additional
data of welding with 4 and 5% (v/v.) nitrogen content in
argon shielding gas was obtained for con®rmation of the