Mechanical Properties and Corrosion Resistance of GTAW Joint of S904L Super Austenitic Stainless Steel Tube

Tungsten argon arc welding with single-sided welding double-sided forming was conducted on S904L super austenitic stainless steel pipe with dimension of φ60 mm×3 mm. The microstructure, mechanical properties, corrosion resistance of the joint were analyzed. The results show that there were no pore, overlap, dent and undercut on the surface of the joint weld, and there were no crack, incomplete fusion, lack of penetration inside weld indicating the good forming performance of the weld. The microstructure of weld consisted of columnar grains and equiaxed grains, and the microstructures of heat affected zone and base metal were both anstenite. The tensile strength of the joint was not lower than 525 MPa, and the joint fractured at the heat affected zone; the fracture type was ductile fracture. No cracks were observed on surfaces of face bending and back bending samples after 180° bending, and the results met the standard requirement. The micro-hardness of the heat affected zone was the highest, and followed by the weld and base metal. The intergranular corrosion sensitivity of the base metal and the weld were relatively small, and the corrosion resistance of the weld in the sulfuric acid was only slightly poorer than that of the base metal.