The first report on the cost of corrosion in Japan had been published at 1977. The report estimated that the corrosion loss in Japan which did not include indirect loss was 1-2 percent of Gross National Product (GNP) at that time. Since then, almost two decades have been passed and the industrial structure has drastically changed. Corresponding to this situation, the committee on the cost of corrosion in Japan was organized at 1999 jointly by Japan Society of Corrosion Engineering (JSCE) and Japan Association of Corrosion Control (JACC). The project was funded by the National Research Institute for Metals (NRIM) in the program of the Ultra-Steels (STX-21) Project. Cost of corrosion at 1997 was estimated by the Uhlig method and the Hoar method. The estimated cost was compared with the past data which was estimated at 1974 by the same Uhlig and Hoar method. In addition to the above estimation, the preliminary analysis by the Input/Output method is performed for estimating the total cost of corrosion including the direct and indirect cost. The overall cost estimated by the Uhlig and Hoar method at 1997 was found to be 3, 938 billion yen and 5, 258 billion yen, respectively, which is equivalent to 0.77% and 1.02% to GNP of Japan. The total cost including the direct and indirect cost, which is estimated preliminary by the Input/Output analysis, is likely to be more than 2 times larger than the direct cost estimated by the Uhlig method.
Structure and properties of the protective rust layers on systematically exposed weathering steels underneath 5 bridges in the main island of Japan for 17 years were investigated using various analytical methods. The weathering steels formed a protective rust layer containing alloying elements such as Cr and Cu. It was clarified that so obtained rust layers on the weathering steels were mainly composed of the goethite (α-FeOOH)-type structure. Protective properties of the rust layers were considered to be related with the suppression of ion transport due to its densely packed structure as indicated by nitrogen adsorption isotherm analysis. The influence of air-borne salt on the rust structure was also elucidated in such a way that content of β-FeOOH and rust particle size increase as the level of air-borne salt becomes high, which would cause less protective performance of the rust layer on weathering steels.