The Welding Deformations of Stainless Steel Pipes With Thick Wall by Narrow Gap Gas Tungsten Arc Welding

The austenitic stainless steel pipes with thick wall are widely used in the nuclear power station and are welded by narrow gap gas tungsten arc welding process. The welding deformations of multi-pass butt-welded pipes with 65 and 70mm thickness are investigated experimentally and numerically in the paper. The transient axial deformation and axis shift deformation are measured during welding. An axisymmetric FE model and a thermal mechanical calculating procedure are presented to simulate the welding axial deformations. An effective calculating method by only considering the contraction of each welding pass in the model is proposed. The experimental results show that the axis shift deformation is very small and demonstrates an elastic movement during welding; the axial shrinkage of welded pipes is the mainly deformation, which is very significant during the first several weld pass, and decreases sharply after the weld groove has been filled at the height of 30% wall thickness that makes the stiffness of pipes large enough to resist the welding shrinkage.