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

Abstract

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∙m^1/2. The FCG acceleration induced by gaseous hydrogen was investigated with experimental and numerical results. The numerically obtained original parameter “effective diffusion depth X_h” based on the gradient of hydrogen concentration qualitatively predicted the experimental hydrogen-induced FCG acceleration.