Hydrogen Embrittlement Analysis in Nitrogen and Vanadium Alloyed Supermartensitic Stainless Steels

Hydrogen embrittlement (HE) is a phenomenon for which numerous models have been proposed over the years to elucidate its underlying mechanisms. This poses a challenge for industry, especially for facilities and components in the oil country tubular goods (OCTG), as it compromises the structural integrity of metallic materials and can lead to catastrophic failures. In this sense, this study investigated the susceptibility to hydrogen embrittlement of two distinct supermartensitic stainless steels, one containing nitrogen micro-additions and the other vanadium. Both alloys underwent different heat treatments representing potential industrial solutions. To detect this phenomenon, slow strain rate tensile (SSRT) tests were conducted under cathodic polarization in an aqueous solution containing 3.5% NaCl. The resulting flow curves were modeled, and the adjusting parameters were compared. Fracture surface analyses were performed using scanning electron microscopy (SEM), enabling the qualitative characterization of failure mechanisms induced by the presence of hydrogen and their correlation with the obtained curves and parameters. The results showed a significant discrepancy between the alloy’s mechanical response to hydrogen charging and a considerable influence of the applied heat treatments. It became evident that microstructural changes, such as the presence of carbides and retained austenite, are directly correlated to embrittlement severity. Therefore, this study is a step forward in the development of safer and more resistant materials for applications in harsh environments within the oil and gas industry.