Hydrogen-Assisted Fatigue and Fracture of 15-5PH Precipitation Hardened Martensitic Stainless Steel

Precipitation hardened (PH) martensitic stainless steels are attractive for their unique combination of high strength and corrosion resistance. Commonly used in the power generation industry where hydrogen and hydrogen blends are being considered as an alternative fuel, high-strength precipitation-hardened stainless steels are generally very susceptible to hydrogen embrittlement. Compatibility of a material with hydrogen depends on the environment, stress, and material properties, thus the specific service conditions determine the compatibility of a material. There is a notable lack of literature on the compatibility of PH martensitic stainless steels for gaseous hydrogen service, particularly as a function of standardized heat treatment conditions. In this study, 15-5PH was heat-treated to three conditions (H1100, H1150D, H1150M) to evaluate the role of heat treatment on hydrogen susceptibility. Thermal H-precharging was performed on smooth and notched tensile specimens followed by testing in air to evaluate the role of internal H on tensile behavior and fatigue life, respectively. Compact tension specimens were tested in-situ in 34 and 210 bar gaseous hydrogen to evaluate external gaseous hydrogen effects on fatigue crack growth rate and fracture toughness. The susceptibility to hydrogen embrittlement was evaluated through the lens of strength, frequency and hydrogen pressure.