Prediction of the Propagation Behavior of a Quarter-Elliptical Corner Fatigue Crack in Clad Steel with Residual Stresses.

Abstract

The present authors previously proposed the U (crack opening ratio)-estimation method for predicting a fatigue life of a two-dimensional crack propagating in residual stress fields based on the superposition principle. This method was extended for application to three-dimensional cracks. In this study the method was applied to a quarter-elliptical corner fatigue crack in residual stress fields in SUS304L-clad SPV32SR steel. Experiments were conducted for three cases; (1) propagation of a corner crack in an SPV32SR specimen in the absence of initial residual stresses, (2) propagation of a corner crack from the SUS304L side to the SPV32SR side of the clad steel, and (3) propagation of a corner crack from the SPV32SR side to the SUS304L side. The prediction method was applied to those three cases assuming that those cracks remained a quarter ellipses. The predicted results were compared with the experimental ones. Good agreement was observed between the predicted and experimental results for case (l). A slight (difference was observed between the predicted and experimental results for case (2), while much better agreement was found between the predicted and experimental results for case (3). Generally the predicted lives were in good agreement with experimental ones and it was confirmed that the present fatigue life prediction method was valid.