Comparison of welding behavior of SUS316L steel by gas tungsten and gas metal arc processes in high pressure nitrogen atmosphere

Austenitic stainless steels of SUS316L were welded by GTA and GMA methods in high pressure nitrogen atmosphere and have investigated the welding condition, nitrogen absorption and microstructure. In the case of GTA welding could not be started arc over 2.1 MPa of nitrogen atmosphere, because the tungsten electrode was remarkably consumed in high-pressure nitrogen. However, in case of GMA welding, welding could be performed up to 6.1 MPa of nitrogen atmosphere at constant welding current of 200 A and the arc length of 7 mm. Arc voltage increased with increase in pressure of nitrogen atmosphere. Nitrogen content of GMA solidified metal increased from 0.2 to 0.65 mass% with increase in pressure from 0.1 to 6.1 MPa. Bending test indicated formation of a few micro cracks in solidified metal that included more than 0.5% nitrogen content. (orig.)