Analysis for the Mechanism of Accelerated Corrosion on Low Alloy Steel in Air-solution Alternating Condition

Abstract

In the present study, the iron rust layer formed on the low ally steel in air-solution alternating condition was investigated by cross-sectional observation and analysis, and the mechanism of accelerated corrosion of the steel in the alternating condition was clarified. Observation and analysis showed that the multi-layered iron rust layer composed of red rust layer （γ-FeOOH）, rust crust layer （Fe₃O₄）, inner crystal （Fe₃O₄）, and inner rust layer was formed on the low alloy steel. It can be considered that the multi-layered iron rust layer accelerated the cathodic reaction rate of dissolved oxygen in the alternating condition. This acceleration would be the reason why the corrosion rate of the low alloy steel in the alternating condition was accelerated.