26 Hydrogen Embrittlement in Super Duplex Stainless Steel Tubes UNS S32750 Under Mechanical Stress

In this study the influence of hydrogen embrittlement in Super Duplex Stainless Steel tubes was investigated in two conditions: as-received and as-welded. The tubes were hydrogen charged by applying different levels of cathodic current into artificial seawater under tensile stress during 160 hours. After hydrogenation, the specimens were submitted immediately to a uniaxial tensile test in order to evaluate how the hydrogen affects its mechanical properties. Additionally, electrochemical hydrogen permeation test was performed. It was observed that the loss of ductility is more pronounced in tubes that have been hydrogenated through higher cathodic currents, especially for samples in the welded condition. The hydrogen diffusivity obtained at room temperature was 6.5 x 10^-15 m² /s.