A microstructure-based fatigue-crack-initiation model

This article presents results on the development of a microstructure-based fatigue-crack-initiation model which includes explicit crack-size and microstructure-scale parameters. The current status of microstructure-based fatigue-crack-initiation models is briefly reviewed first. Tanaka and Mura's models([1,2]) for crack initiation at slipbands and inclusions are then extended to include crack size and relevant microstruetural parameters in the response equations. The microstructure-based model for crack initiation at slipbands is applied to predicting the crack size at initiation, small-crack behavior, and notch fatigue in structural alloys. The calculated results are compared against the experimental data for steels and Al-, Ti-, and Ni-based alloys from the literature to assess the range of predictability and accuracy of the fatigue-crack-initiation model. The applicability of the proposed model for treating variability in fatigue-crack-initiation life due to variations in the microstructure is discussed.