On the prediction of corrosion fatigue in the presence of residual stresses

Residual stresses can play a vital role in slowing down or accelerating corrosion fatigue in offshore structures, depending on their types and magnitudes. Despite the importance of this issue, considering their effects on corrosion fatigue assessments presents very challenging investigations. In the current study (which is a continuation of the authors' previous research containing no consideration of residual stresses), corrosion fatigue behaviour as well as the capability of using artificially pitted specimens in corrosion fatigue tests in the presence of tensile and compressive residual stresses was studied. Furthermore, the shot peening process was examined as an alternative method of repairing to extend the life of corroded samples. Moreover, fatigue and corrosion fatigue lives in the presence of residual stresses were predicted based on the fatigue data and in the absence of residual stresses only. Also, predictions were made using a continuum damage mechanics and the finite element approach. Experimental results showed that the specimens containing artificial pits can be considered as a replacement for the pre-corroded samples in the experimental tests with some considerations. They also illustrated that the shot peening process could enhance the life of corroded specimens significantly. Numerical results were in a good correlation with the experiments which confirmed the potential of the adopted simulating strategy that eliminates the requirement of conducting many experiments for model calibration.