An investigation of the effects of corrosion on the fatigue strength of AlN axle steel

Abstract

Corrosion fatigue is an important topic in the evaluation of the structural integrity of railway axles. In fact, several recent axle failures have been attributed to the presence of corrosion pits and axle surface corrosion. Despite the importance of this issue, existing EN standards do not precisely quantify the effect that corrosion or corrosion-fatigue might have on the fatigue strength of a railway axle. Consequently, there is a need to have a better understanding of this problem. In this paper, two main lines of research have been adopted with a view to investigating the issues regarding the corrosion fatigue properties of AlN steel. The first line of research assesses the morphology and the statistical distribution of corrosion defects present on the surface of retired axles together with the detrimental effect of the defects detected on the in-air fatigue strength of AlN steel. The second line of research examines the fatigue properties of AlN steel in the presence of artificial rainwater. The results of the analysis show that the corrosion typically found on axles is significant from a point of view of fatigue properties and that the fatigue life of AlN steel is strongly affected by the presence of a mildly corrosive substance like rainwater. Fatigue test results are consistent with the fatigue strength reduction outlined in the BASS technical recommendations.