Effects of corrosion morphology on the fatigue life of corroded Q235B and 42CrMo steels: Numerical modelling and proposed design rules

This study presents a detailed numerical analysis to examine the effects of corrosion morphology on the fatigue life of corroded Q235B and 42CrMo steels. To obtain the actual corrosion morphologies, a 3D digital model of Q235B and 42CrMo steels after indoor accelerated corrosion was obtained using the three-dimensional (3D) scanning method. After that, the corrosion morphologies of the test specimens were extracted and then stored in a database for further parametric study, and the specimens with different corrosion morphologies can be obtained by randomly selecting and combining the morphology meshes from the database. Finite element (FE) models were then developed, and validated against the experimental results reported by the authors previously. A parametric study was carried out to investigate the influence of different corrosion morphologies on the fatigue properties of Q235B and 42CrMo steels. Finally, the fatigue life prediction model was proposed in this study, which can establish the relationship between the exposure time and the fatigue life of the corroded steels. The numerical results suggested that the average cross-section area and thickness have a significant effect on the fatigue properties of Q235B and 42CrMo steels. The newly proposed prediction model can provide accurate predictions for predicting the fatigue life of corroded Q235B and 42CrMo steels.