Corrosion of ordinary structural steel (JIS-G 3101; SS 41) in sea water was studied by considering the change of seasonal factors, such as temperature, oxygen content and activity of sulfate-reducing bacteria.
The results obtained are as follows.
(1) The corrosion rate of this steel in sea water was highest in summer. Localized corrosion was found only in this season.
(2) The biological activities of sulfate-reducing bacteria had a direct influence on the corrosion of this steel in spring and summer.

抄録全体を表示

The adsorption behavior of atmospheric moisture on paper and corrosion of steel in contact with paper bearing condensed water have been studied by determining adsorption isotherms, electric resistivity and the intensity of corrosion. The following conclusions were drawn from the results.
(1) Distribution of adsorbed water across paper is not uniform at any humidity.
(2) For the same amount of adsorbed water, capillary condensation takes place more intensively near the surface as the temperature rises.
(3) The corroded area of steel in contact with paper for 24 hours increases exponentially as the adsorbed water increases up to some level in the capillary condensation region.
(4) Further increase of adsorbed water in the above region, however, gives relatively little increase in the corroded area.
(5) There is a close correlation between the corroded area of steel and the surface resistivity of the paper in contact.
(6) The lowest humidity above which corrosion proceeds is about 42% R. H. at 40°C. The value becomes greater as the temperature falls.

抄録全体を表示