Evaluation of the Susceptibility of a Superduplex Stainless Steel Welded Joint to Sulfide Stress Corrosion by Slow Strain Rate Tensile Tests in Sour Solutions

The usage of superduplex stainless steels in offshore petroleum production has increased considerably in the last years. Particularly, the use as flowline pipes for oil production needs careful research on the effect of critical environmental conditions on the stress corrosion resistance of welded joints. In this work, welded joints of UNS S32750 were produced by automatic gas tungsten arc welding (GTAW-orbital) using a J-groove weld geometry. The welded joints were evaluated using slow strain rate tensile tests in acid solutions containing hydrogen sulfide (H₂S) and chloride. H₂S partial pressure and pH were varied to determine safe operating conditions. Specimens tested at pH = 3.5 and p(H₂S) = 3.75 and 6.75 showed brittle behavior. The specimens tested with lower p(H₂S) or higher pH exhibited ductile behavior.