To utilize the inhibition effect of magnetic field on metal dissolution, it was required to be examined in the flowing conditions of solutions. A 100cm³ of 0.015mol dm^-3 nitric acid solution for zinc and of 1.5mol dm^-3 nitric acid solution for copper and brass were used respectively. The flowing rate of solutions were changed from 0 to 27cm³ min^-1. A column with a sintered-glass filter (G1) (10.5mm∅×80mm) was used, and the nitric acid solutions were circulated upward through the column. The dissolution rate of copper, zinc and brass were reduced by the magnetic field effect. The inhibition effect was larger in the solutions in the stationary state or in the flowing solution with low flow rate than that with high flow rate, and it had no dependence on the direction of line of magnetic force. The selective dissolution of crystal planes on metal surface were slightly brought about by magnetic field. The magnetic field activated dissolution of copper in flow of fresh nitric acid solution. The magnetic field effects did not appear in the solution side but in the metal side.

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Noise analysis has become an important method for studying localized corrosion such as pitting corrosion on stainless alloys. The noise observed from anodic polarized stainless alloys is in the form of current fluctuations caused by the localized breakdown and repassivation of passive film. In this study, the current fluctuations from anodic polarized SUS 304 stainless steels and Fe-Cr-Si-B amorphous stainless alloys in 3% NaCl solution are measured. The shape, size, and other characteristics of each current fluctuation are analyzed.
The results are as follows. Passive film breakdown, pit growth and repassivation processes include a great random factor. Also both the pit growth rate and the repassivation rate become higher with potential rise. Amorphous stainless alloys indicate an extremely high repassivation rate which is related to a high pitting potential.

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Diagnoses and remedies of corrosion failure of 13 Cr martensitic stainless steel parts used for hydraulic machines in fresh water at ambient temperature and in high purity water at high temperature are presented. The failures of the rotation parts in the hydraulic machines were occurred by SCC or corrosion fatigue induced with pitting and intergranular corrosion in these mild environments. These localized corrosion may be attributed to the sensitization by medium tempering temperature of 13 Cr martensitic stainless steels. On the other hand, the failures of the sliding contact parts in the hydraulic machines were occurred by brittle fracture induced with micro-pitting. These failures may be attributed to the presences of the abnormal stress caused by high hardness of hydraulic machine in service duration. Possible methods to prevent these failure may be use of the non-sensitized materials by full annealing for rotation parts and be use in the normal stress condition for sliding contact parts. No failure has been reported for over long duration since the countermeasures had been adapted.

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In coastal areas, sea-salt particles floating in the air above the ocean are blown toward by the wind and adhere to the surface of metals, severely corroding them. Japan is an island country and thus, salt damage is the most impotant factor affecting atmospheric corrosion. However, sea-salt-particle level decreases with increasing distance from the coast. Other factors such as temperature and precipitation also affect the corrosion rate. Therefore, it was difficult to determine the corrosion rates at each area. A method has been developed for estimating the atmospheric corrosion rate of zinc caused by airborne salinity. The method estimates the corrosion rate from easily available data such as temperature, humidity, precipitation, direction and velocity of wind, and distance from the coast. The accuracy of the method was ±30% compared with the results of field tests.

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Importance of corrosion in the maintenance of steel bridges is described. Implementation of dehumidification plant to protect inside of steel box section from corrosion is explained. A measurement of corrosion environment inside the steel box tower/girder is being conducted using clean steel specimens and some results are also presented.

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