A comprehensible explanation of the hard and soft acids and bases principle (HSAB principle) is described in this review first. Inhibition and stimulation of the anodic process for iron corrosion in an acid solution containing various anions are interpreted on the basis of the HSAB principle. Further, effects of anions on passive film breakdown of iron in solutions of various anions are discussed using the principle.
In order to obtain the relation between an intergranular corrosion behavior and an impurities for stainless steel, cellular automata modeling and simulation of intergranular corrosion was carried out. From intergranular corrosion simulation considering non-uniform phosphorus component distribution on grain boundary, it suggested that complicated intergranular corrosion shape as in experimental data was caused by the large precipitation of phosphorus compounds in part of grain boundary.
Cathodic protection is applied to prevent AC corrosion and soil corrosion, which are generated in holiday of buried coated steel pipe. However, there is no way to measure the current density flowing into holiday, cathodic protection is managed as an index to earth surface potential or the current density of a probe buried near the steel pipe. We developed new method for estimating the alternating current density by non-digging. Also we showed the effectiveness of the method through the verification experiment. The proposed method is expected to be applied for cathodic protection management of buried steel pipe.