A Study of X-Ray analysis of fatigue fracture surface

Abstract

An X-ray analysis was made of the fatigue fracture surface of SM50A steel. The residual stress and the half-value breadth of the diffraction intensity curve were examined on and under the fracture surface. An analytical study was also made of the residual stress and strain near the fatigue crack surface by using the finite element method. Emphasis was on finding the correlation between the residual stress or the half-value breadth and the applied stress intensity factor of K max or † K. It was found that both the residual stress and the halfvalue breadth distributions under the fracture surface were useful for the estimation of the monotonie plastic zone size or K max .The correlation of the absolute value of the residual stress with K max or † K, however, was not clear in the present study. From the analytical study, it was found that the effect of the surface contact due to fatigue crack closure on the residual stress was less important and limited to the thin layer near the crack surface.