1983 年 32 巻 354 号 p. 264-270
An X-ray fractographic study was made on the fatigue fracture surface of SM50A steel. The residual stress and breadth of the diffraction intensity curve were measured at and beneath the fracture surface. The analysis of residual stress on the fatigue fracture surface was also conducted by using the finite element method. An emphasis was made on finding the correlation between the residual stress or the plastic zone size determined from the X-ray measurements and the applied stress intensity factor.
Both the distribution of residual stress and half-value breadth were found to be useful for the prediction of monotonic plastic zone size or Kmax, although it still remained in question for the possibility of estimating cyclic plastic zone size. The correlation between the surface values of residual stress and the applied stress intensity factor was not clear in the present study.
The effect of fatigue crack closure on the residual stress of the fracture surface was found to be relatively small and limited in the very thin layer near the fracture surface.