Abstract
The positive effect of nitrogen in the backing gas on the pitting corrosion resistance when welding duplex stainless steels with the gas tungsten arc welding (GTAW) process is discussed and the further improvement with up to 10 % hydrogen emphasised. In this work, 16 mm thick super duplex EN 1.4410/UNS S32750 was welded with three different backing gases (100 % Ar, 100 % N2 and 90 % N2 + 10 % H2) in a butt joint with and without root gap. The rest of the joint was filled using the flux-cored arc welding (FCAW) process. The fillers were of ISO 25 9 4 NL type. The welds were subject to ferrite measurement, impact toughness, tensile, hardness and bend testing, while pitting corrosion resistance was determined in accordance with ASTM G48 Method E. The welds performed with 100 % Ar showed somewhat higher impact toughness, but it was only the 90 % N2 + 10 % H2 welds that passed the corrosion test.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
