Effects of hydrogen and casting defects on the fatigue behavior of Cu–Al–Ni–Fe–Mn cast alloy

Fatigue tests on Cu–Al–Ni–Fe–Mn cast alloys were conducted under hydrogen-free and hydrogen-precharged conditions. The hydrogen-precharged specimens were exposed to hydrogen gas at 100 MPa and 270 °C for 200 h to ensure a uniform hydrogen distribution. Rotating-bending fatigue tests were performed at 0.1–10 Hz at room temperature. Fractures consistently originated from casting defects, regardless of hydrogen charging. To isolate the defect's effect, an artificial defect was introduced. Hydrogen charging slightly extended the fatigue crack initiation life without accelerating the crack growth rate, resulting in a slight increase in total fatigue life. The fatigue limit was also marginally higher in hydrogen-precharged specimens. Although localized slip deformations induced by hydrogen were observed, their negative effects on fatigue properties were negligible. The dominant positive effect was attributed to increased hardness, while the overall impact on fatigue life remained slight, likely due to the low hydrogen content and the alloy's FCC structure.