Fatigue and Fracture Behavior of Low-Alloy Wrought and Cast Steels in Gaseous Hydrogen

Abstract Low-alloy steels offer an attractive balance of affordability and performance for natural gas infrastructure applications. These materials can be utilized to fabricate thick components, which are then heat treated for use in valves, pipelines, pressure vessels, and flanges. With a growing focus on enhancing the energy sector, hydrogen is a promising solution to achieve greater diversity and resilience of energy assets. However, the performance of cast low-alloy steels in comparison to wrought steels in such demanding environments has yet to be thoroughly assessed. Notably, thick-walled vessels made from cast steels may exhibit a higher tendency for porosity, raising concerns regarding their compatibility with hydrogen. This study investigates the fatigue and fracture behavior of ASTM(1) A352 LCC, a cast steel, and ASTM A350 LF2, a wrought steel, when in the presence of 210 bar of gaseous hydrogen. The microstructures of both cast and wrought steels are analyzed and compared to previously evaluated low-alloy pressure vessel steels and low-carbon pipeline steels. Additionally, the fatigue performance is benchmarked against the recently established ASME Code Case 2938-2 fatigue design curves.