Fracture Toughness and Fatigue Behavior of Carbon and Stainless Steel in High Pressure Hydrogen

Abstract In response to the growing demand for hydrogen energy and the need for large-scale underground storage, this study evaluates the fracture toughness and fatigue behavior of oil country tubular goods (OCTGs) materials under high-pressure hydrogen environments. Sour-service carbon steels (L80, T95) and stainless steel (L80-13CR) were tested at 38 MPa hydrogen pressure to assess their suitability for hydrogen storage wells. Fracture toughness values were obtained using ASTM(1) E1820-20b, and required toughness values were calculated based on API(2) 579-1/ASME(3) FFS-1 guidelines considering potential defect scenarios. All tested materials exhibited fracture toughness values at least 2.4 times higher than the required thresholds, indicating sufficient safety margins. Fatigue tests simulating seasonal pressure fluctuations in underground storage were conducted under 39–40 MPa hydrogen pressure, revealing no crack initiation in any specimen. These results demonstrate that L80, T95, and L80-13CR possess adequate resistance to hydrogen embrittlement and fatigue, confirming their applicability for use in high-pressure hydrogen storage wells.