An Analysis of Macro- and Microstresses Around a Fatigue Crack Tip

Abstract

We have investigated the stresses existing before and during fatigue crack growth in a 1080 spheroidized steel. The total stress state, which consists of triaxial macro- and microstress components, has been measured around the fatigue crack tip using x-ray microbeam diffraction. A tapered glass capillary of 210μm diameter has been developed to provide increased intensity, smooth diffraction peaks and good spatial resolution. Findings indicate that stresses generated by the growing crack are mainly macro stresses, and dominate over pre-existing residual stresses around the tip.