塩化物を含む乾湿繰り返し環境におけるCu-P系耐食鋼の腐食特性

抄録

Paid particular attention to the characteristics of rust layers, this study was conducted to research the corrosion behavior of low-alloy steel containing small amounts of Cu and P in the saline environment which composes cyclic variation between wet and dry periods. Corrosion resistance of the low-alloy steel depends on the relative humidity of atmosphere in dry periods. According to the results of the X-ray diffraction analysis of rust layers and polarization measurements, cathodic reaction of the low-alloy steel exposed to this environment is reduction of β and γ FeOOH to Fe₃O₄. EPMA analysis of rust layers indicates that localized corrosion of low-alloy steel proceeds in chloride nest to which chloride ions are concentrated. The tight rust layer containing Cu acts as effective barrier to the permeation of chloride ions.