Hydrogen Diffusion−Elastoplastic Coupling Analysis for Hydrogen Concentration Gradient around a Blunting Crack Tip

For a fatigue crack growth (FCG) test of carbon steel, JIS-SM490B, in gaseous hydrogen, hydrogen diffusion / Elastoplastic coupling FEM analysis was performed with various combination of hydrogen-gas pressure from 0.1 to 90 MPa and test frequency from 0.001 to 10 Hz, and stress intensity factor from 12 to 40 MPa∙m1/2. The FCG acceleration induced by gaseous hydrogen was investigated with experimental and numerical results. The numerically obtained original parameter “effective diffusion depth Xh” based on the gradient of hydrogen concentration qualitatively predicted the experimental hydrogen-induced FCG acceleration.