Abstract
The hydrogen-assisted fatigue crack growth behavior in a ferritic Fe-3wt.%Si alloy was studied via in-situ electrochemical hydrogen charging and post-mortem characterization. The crack propagation rate was severely increased by the introduction of hydrogen by up to 1000 times, in comparison with a reference test in laboratory air. Fractographic analysis showed strong difference in the resulting fracture features: “quasi-cleavage” features were strongly promoted by hydrogen. Advanced scanning electron microscopy (SEM) characterization techniques including electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) were adopted to investigate the details in fatigue crack propagation behaviors with and without hydrogen. The possible mechanisms in hydrogen-assisted cracking in ferritic alloys were discussed.