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

Abstract

In this study, the iron rust layer formed on the low alloy steel under air-solution alternating conditions was investigated by cross-sectional observation and analysis, and the mechanism of the accelerated corrosion of the steel under alternating conditions was clarified. The observations and analysis showed that the multilayered iron rust layer composed of the 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 multilayered iron rust layer accelerated the cathodic reaction rate of dissolved oxygen under alternating conditions. This acceleration is the reason why the corrosion rate of the low alloy steel under alternating conditions was accelerated.

 

This Paper was Originally Published in Japanese in Zairyo-to-Kankyo 68 (2019) 205–211.

Fig. 11 Schematic representation of the mechanism of accelerated corrosion of low alloy steel in air-solution alternating condition.