A Method for Measuring of Hydrogen Diffusion Coefficient of a Low Alloy Cast Steel for Train

The method of electrochemical hydrogen permeation in a double electrolytic cell was applied to measure the diffusion coefficient of hydrogen in a low alloy cast steel. The modified hydrogen permeation formula based on semi-infinite diffusion model was applied to evaluate the effects of the thickness of testing specimen, the current of charging hydrogen and experimental temperature on the measured value. The results indicate that the thickness of experimental sample did not exert influence on the measured value of diffusion coefficient of hydrogen. However, from the viewpoint of homogeneity of the material, more accurate measured value would be obtained by measuring a thicker sample. the observed value was closer to the theoretical value with increasing the current density of charging hydrogen. Rising experimental temperature could increase the diffusion coefficient of hydrogen, D=0.052 8 exp (-22.47/RT).