Crack Closure Effect and Crack Growth Life Prediction for GH2036 Superalloy Plate

In order to examine the crack growth behavior of GH2036 supealloy subjected to low cycle fatigue (LCF) loading, crack growth experiments on GH2036 superalloy plates under different stress ratios at 550℃ were performed and the crack opening stress intensity factor of GH2036 superalloy were measured using Digital Image Correlation (DIC) technique. Results indicate that no crack closure is observed at 550℃ when the stress ratio is greater than 0.7. Meanwhile, crack closure model in GH2036 superalloy was established in terms of the residual crack tip opening displacement and stress ratio. In addition, SEM analysis of fracture reveals that with the increase of stress ratio, the fracture mode at the crack growth region changes from transgranular to intergranular. Finally, crack growth life of GH2036 superalloy under LCF loading is predicted using the established crack closure model in GH2036 superalloy plates. Low life scatter factor through model validation shows satisfactory results of the predicted crack growth life model.