An information retrieval system of computer programs has been proposed for processing a large amount of corrosion data obtained both in laboratory and in field tests and experiences. This system can accept various types of data, i. e. numerical, non-numerical, and graphic data as input, which are not restricted by their quality and quantity. The user of the system can refer desirable informations from the file with a name of material, temperature, a name and composition of environmental solution, etc. This is useful to know not only the limit of corrosion resistance of materials but also the influence of environmental factors.

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To investigate the effect of zinc content distribution on pit growth rate toward the direction of thickness, immersion test has been carried out in tap water containing 1ppm Cu⁺⁺ on vacuum heated Al-Zn, Al-Mn-Zn and Al-Mg-Zn alloys. Pitting potential of aluminum alloys decreases with zinc content, whereas, no apparant difference is observed on pit growth rate between the materials having various profiles of zinc. This is attributed to the relatively uniform anodic dissolution of the alloys containing small amount of zinc in the solution within pit.

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The effect of heat treatment preceded by cold rolling on the corrosion resistance and the hydrogen absorption of commercially pure titanium in a boiling 1%H₂SO₄ solution was investigated. The results obtained are summarized as follows:
(1) The corrosion loss and the amount of absorbed hydrogen of titanium annealed at 550°C are larger than those of as-cold rolled titanium. The textural change seems to be responsible for this phenomenon.
(2) The corrosion loss and the amount of absorbed hydrogen of titanium decrease gradually with the raising of the annealing temperature from 550°C to 880°C. This phenomenon can be explained by the precipitation of iron at grain boundaries of alpha phase. Consequently, in titanium annealed at higher temperature, corrosion resistance of grain boundary becomes inferior because of precipitation of iron compound but the corrosion resistance of the grain is improved by decreasing iron content. As a result, corrosion loss of titanium annealed at 800°C is smaller than that of titanium annealed at 550°C.
(3) The corrosion resistance of titanium annealed at 1000°C is greatly deteriorated. The reason is why less corrosion resistant acicular alpha phase comes out.

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Critical pitting potential was measured for copper tubes in a flowing synthetic water at 60°C. The chemical composition of the synthetic water (HCO₃^- 36.6, Cl^- 42.6, and SO₄^2- 76.8mg/l) was selected from chemical analysis data of waters prone to pitting. Anodic polarization curves did not give current rise due to pitting. Thus it was impossible to determine the critical potential from polarization curves alone. The critical pitting potential of 150mV (SCE) was determined by optical microscopic examination of potentiostatically polarized copper surfaces at various values of potential. X-ray and EPMA analysis showed that the products inside a pit were Cu₂O and CuCl, and that the green product overlaying a pit was Cu₄(OH)₆SO₄. The structure and morphology of the pit were the same as those reported for the type II pitting of copper, which is commonly observed in soft waters with low [HCO₃^-]/[SO₄^2-] ratio.

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The recent studies of corrosion resistance of the stainless steels in hot water environment are reviewed. The new ferritic stainless steels which are resistant to SCC and IGC are most promising for application to this environment. More studies are necessary to increase resistance to crevice corrosion through better design and fabrication, and more quantitative studies concerning concentrating behavior of the anolyte in the crevice are required for reliability of the application.

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