Corrosion induced degradation of fatigue strength of steel in service for 128 years

A rare opportunity has been seized to study the corrosion effect on fatigue strength of steel after service for 128 years. This paper presents a comprehensive experiment on degradation of fatigue strength of steel under simultaneous natural corrosion and service loading. Fatigue tests, tensile tests and microstructural analysis are carried out, and the mechanism of degradation of fatigue strength of corroded steel is examined fundamentally. Relationship between fatigue strength, corrosion and tensile strength are developed. It is found in this study that corrosion can reduce the fatigue strength by altering the microstructure of corroded steel. It is also found that the effect of corrosion on degradation of fatigue strength can be overestimated with accelerated corrosion, and more importantly, it can be underestimated without considering the simultaneous cyclic load effect during the corrosion. The significance of this study is that it not only quantifies the effect of corrosion on degradation of fatigue strength but also provides a more accurate understanding of cause-effect relationships among corrosion, fatigue strength and microstructural characteristics of steel in the most common environment (atmospheric) and loading applications (traffic loads), thereby contributing to the body of knowledge of corrosion science of steel.