Field corrosion tests of various kinds of stainless steel were carried out for ten years, partly for three years, to select optimum construction materials in the down stream of pasteurizing unit. Resistance to localized corrosion was also evaluated by measuring anodic polarization characteristics in soy sauce and sodium chloride solution. Pitting and crevice corrosion was the most remarkable with SUS 304, followed by SUS 316L and the least remarkable with SUS 317J1. Pitting and crevice corrosion of SUS 329J1 was less remarkable than these of SUS 444. The consistency of the result of field corrosion test for long term and the result of anodic polarization characteristics was confirmed. Dissolved oxygen concentrations and natural electrode potentials in soy sauce, amino acid, sodium chloride solution suggested that initiation and growth of the localized corrosion of stainless steels would be restrained in the brewing soy sauce, because of its lower concentration of dissolved oxygen than sodium chloride solution.

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Intergranular corrosion of austenitic stainless steel is associated with the Cr depleted zone surrounding Cr carbide precipitated at grain boundary. Computer simulation program of intergranular corrosion, caused by attack of Cr depleted zone, was developed to predict intergranular corrosion susceptibility. Assuming that the formation of Cr depleted zone adjacent to grain boundary is controlled by carbide nucleation rate, thermodynamical property of carbide and Cr diffusion coefficient, two-dimensional redistribution of Cr concentration on grain boundary was calculated by differential method. Induction time of carbide precipitation was calculated by taking account of the effect of C, Cr and Ni content based on the nucleation theory. Calculated corrosion depth in Strauss test coincided well with experimental data in specimens heated at the temperature range of 823 to 1073K and cooled from 1073K. From these results, this computer simulation is found to be able to predict the sensitization of SUS 304 steel heated at the range of 823 to 1073K.

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A study was made of the effect of addition of NO₃^- ions on the corrosion of titanium in HCl solutions. For titanium, NO₃^- ions was necessary to add at least 0.008kmol·m^-3 (0.05mass%) to achieve corrosion inhibition in HCl solutions. Above this concentration, titanium passivates, and hydrogen pick up by titanium was also prevented. Ti³⁺ ions near surface seem to be quickly oxidized by NO₂ formed with other products in the reduction of NO₃^- to Ti⁴⁺ in the reaction Ti³⁺+NO₂→Ti⁴⁺+NO₂^-. As a result, titanium passivates and corrosion inhibition of titanium is achieved.

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Copper is widely used to make cables, printed circuit boards and various structural components. However, copper tends to form thin film of oxide or sulfide on its surface, presenting tarnished appearance or undesired effects such as lowering of electrical characteristics. The present study elucidates the growth mechanism of such film through analysis of the influence of temperature, humidity, contaminating substance, surface treatment and impurity gases (SO₂, HCl, H₂S) on the growth speed of the film. It was found out that the long-established cathodic reduction technique was the simplest and yet considerably accurate analyzing method.

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Since fine ceramics are superior to metals in corrosion, heat and wear resistance, it is the key technologies for industrial progress to apply them to industrial field. While, fine ceramics have so poor toughness to fracture under stress concentration relatively easily and therefore it is difficult to utilize them to industrial products. This report shows the application examples and problems of fine ceramics applied to industrial field, mainly combustion engines and chemical plants.

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For the corrosion protection of marine structures immersed in sea water such as ship hulls, condensers of power station and buried submarine pipe lines, catholic protection is effective. This report describes the concept of cathodic protection method and the result of its application to corrosion caused by dissimilar metal contact in narrow crevice.

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