The content at the reversible potential of hydrogen evolution reaction, diffusion coefficient and permeation rate of hydrogen in deformed mild steel were measured with a modified electrochemical technique. The dislocation density of such specimens was estimated from the integrated breadth of the profile of X-ray diffraction. From these experiments we obtained the following conclusion: (1) The content and diffusion coefficient of hydrogen in the undeformed specimen showed a good agreement with those given by Gonzalez' equation. (2) The plastic deformation was found to increase the content and to decrease the diffusion coefficient, and to change occlusion mode from endothermic to exothermic. (3) Such change in occlusion mode could be explained with an interaction between dislocation core and hydrogen. (4) The relationship obtained in the present study between dislocation density estimated from the amount of content and true strain was found to be in good agreement with previous results such as estimated from the profile of X-ray diffraction.

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The mechanism of nodular oxidation on 13Cr-0.3C stainless steel at the quenching treatment, and the effects of base metal were studied by EPMA and electron diffraction analysis. Nodular oxidation scale was constructed from two layers, outer layer was mainly consisted of Fe-oxide but inner layer included Cr-oxide. Normal and uniform oxidation scale was identified as Cr₂O₃ film. It was detected that a large quantity of precipitates identified as β-Cr₂N or CrN were found on the interfacial surface under the nodular oxidation scale, and that the specimen included larger quantity of N showed higher ratio of nodular oxidation. Nodular oxidation of Fe-Cr alloy did not occur only in case of which the normal scale consisted of Cr₂O₃ film was cracked to oxidize Fe directly, but in case of inevitable depletion of Cr at the interfacial surface under normal oxidation scale because of preferential oxidation of Cr. From these facts, Cr-nitride was mentioned as one of the factor of nodular oxidation on Fe-Cr alloy. Namely the location where the precipitation of Cr-nitride depleted metallic Cr, that is the effective Cr, under normal oxidation scale growed into the site of nodular oxidation.

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It has been well known that titanium has low susceptibility against pitting corrosion in halide solutions because of its highly stable surface film. However, we have encountered a pitting corrosion of commercially pure titanium in chemical equipment handling a bromide solution at high temperature. Some peculiarities were observed in the corrosion accident; Only JIS grade 1 of titanium was subject to pitting corrosion while grade 2 and grade 3 were not attacked. Furthermore, pit formation occurred only in polished zone of grade 1 surface.
In order to interpret these corrosion behaviours, laboratory tests were conducted on the effects of a small amount of impurity elements, such as oxygen and iron, and surface treatments on the pitting potential of commercially pure titanium.
The electrochemical test results revealed that pitting potential of titanium became higher in the following order, grade 1>grade 2>grade 3 at higher temperatures while the order was reversed at lower temperatures. In addition, surface oxidation treatment improved the resistance of titanium against the pitting corrosion.
These phenomena seem to be related to the intermetallic compound TiFe precipitated in titanium and the stability of the passive film which is affected by oxygen in titanium substrate.

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A technique is described for measuring the true pipe-to-soil potential of buried pipelines by means of an analog probe simulating a holiday in a coating on steel. Examples are given comparing data obtained from traditional measurements and the alternate. Results are also described of the practical applications to the field pipe-to-soil potential survey as well as corrosion rate survey.

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