Abstract
In discussing the delayed failure of steel concerning the hydrogen embrittlement, it is important to understand the behavior of hydrogen, especially the occlusion and the permeation controled by the diffusion.
As to the diffusion of hydrogen in steel, many results of investigations have been reported, but many of them are obtained at high temperature. And there are a few investigations which are made at room tem-perature or below. Especially, the systematic investigations of the effects of the compositions and the structures have been rarely made.
In this report, considering these points, the hydrogen diffusion at the occlusion and the permeation at the room temperature is treated. As to the hydrogen diffusion in steel, Fick's law has been admitted Then, using the mild steel, the volumes of the occluded and the permeated hydrogen were determined by cathodically electric charging for various thicknesses, and comparison was made of the relation between the experimental results and the values which can be calculated using Fick's law and the diffusion coefficient offerd by Hobson.
The results of authors experiments are that the occluded hydrogen and the hydrogen distribution at the occlusion are comparable with the theoretical value, and in the case of permeabilty, the experimental value is a little greater than that of the theoretical value. And authors made sure that the hydrogen solubility for the mild steel, used in those experiments and under the condition of cathodical charging, was 43 cc/100g Fe.
