Analysis of Factors Affecting Fatigue Crack Growth Life in Hydrogen Storage Vessels

Abstract In this paper, based on the mechanical properties, fatigue crack growth rate and fracture toughness of 4130X steel under 45MPa hydrogen environment, the following studies are carried out: (1) the step-by-step accumulation method and step iteration method used in GB/T 19624 and ASME BPVC Section-VIII Div.3 (ASME VIII-3) for the calculation of fatigue crack growth life were compared and analyzed. (2) Based on the methods in the two standards, the effects of different stress intensity factor (KI) calculation methods and fatigue crack growth rate models on the fatigue analysis results are investigated. (3) The effects of loading conditions, material parameters and vessel geometry on the fatigue evaluation results are investigated. The results show that: (1) The difference in calculation process does not affect the results of crack growth life calculation. (2) The KI calculated by the ASME VIII-3 method is larger than the KI calculated by the GB/T 19624 method, resulting in the crack growth life calculated by ASME VIII-3 being smaller than that calculated by GB/T 19624. (3) The decrease in material fracture toughness, yield strength and wall thickness all lead to a decrease in fatigue life. Fatigue life increases rapidly with increasing pressure ratio. Fatigue life shows the greatest sensitivity to the fatigue crack growth rate parameter, and small changes in the fatigue crack growth rate parameter can have a large effect on fatigue life. When carrying out the design of hydrogen storage vessel, the influence of the fatigue crack growth rate parameter on fatigue life should be emphasized.