Fatigue Crack Propagation Behavior of AZ61 Magnesium Alloy under Controlled Cathodic Potential

In the present study, fatigue crack propagation (FCP) tests on Mg alloy, AZ61, were performed in 3% NaCl solution. The cathodic potential was controlled to achieve the hydrogen charged condition without anodic dissolution to figure out the effect of hydrogen on FCP behavior. The cathodic potential was set to be-3.0V, which corresponds to the immunity region without corrosion reaction based on Pourbaix diagram of Mg. The FCP rates were accelerated under hydrogen charged condition compared to those in dry air. Magnesium hydrides, MgH2, were not detected along the crack wake in the measurement by X-ray Diffraction (XRD) method, suggesting that the acceleration could be attributed to the diffusion of hydrogen atoms.