Evaluation of the residual fatigue lifetime of a semi-elliptical crack of a Low-Alloy steel pressure vessel under High-Pressure gaseous hydrogen

The demand for broadening fatigue crack growth behavior has increased owing to the extended use of hydrogen gas as an energy carrier, and it is known that high-pressure hydrogen has a major effect on fatigue crack growth behavior. In this study, the effect of high-pressure hydrogen on an SA-372 Grade J steel pressure vessel was analyzed using fatigue crack growth testing, fracture toughness testing, and finite element analysis. A test was performed to compare the fatigue crack growth of SA-372 Grade J steel in ambient air and 99-MPa hydrogen environments. The test results, including the identified degradation of fracture toughness and the presence of hydrogen inflection in the fatigue crack growth rate, were used in the finite element analysis to analyze the fatigue crack growth behavior under various loading and environmental conditions. The residual fatigue life was evaluated considering the morphological evolution of the crack during growth, the initial aspect ratio, and the initial crack-to-depth ratio.