In the first part of the paper, in view of the data scatters of hydrogen diffusion coefficient in metals, a simplified model was developed which can be used to deal with the diffusion of hydrogen in metals and the corresponding phenomenon of hydrogen trapping. Based on the solution of hydrogen diffusion equation deduced from the ideal condition, the simplified model, in which the effect of hydrogen trapping in metals is completely eliminated, can be used to get the lattice diffusion coefficient of hydrogen in metals more accurately. By use of this simplified model the expression of the lattice diffusion coefficient of hydrogen in α-iron in the vicinity of room temperature was obtained, and the trapping of hydrogen in α-iron was also studied. In the second part of the paper, in view of the experiment fact that the apparent diffusion coefficient of hydrogen in metals increases with the increase of the hydrogen permeation time, a model in which hydrogen diffusion coefficient is dependent on the hydrogen concentration was first developed to describe the diffusion of hydrogen in metals. From the numerical solution of the hydrogen diffusion model newly developed the theoretical hydrogen permeation curves under the two supposed conditions, i.e., the normal hydrogen trapping dynamics and the local equilibrium assumption of hydrogen trapping, were obtained, respectively. Finaly, by the application of the hydrogen diffusion model to the hydrogen permeation experiment results, a well satisfied result was achieved and the corresponding hydrogen trapping parameters were also obtained.
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