抄録
Investigations have been made on the fatigue crack propagation behavior of surface pre-cracks in tensile residual stress fields induced by water-cooling from the temperatures of 873 K and 673 K, as well as in no residual stress fields. The analysis for a three-dimensional crack in an infinite body, proposed by R.C. Shah and A. S. Kobayashi, has been used for determining the stress intensity factor of a surface crack, in consideration of the correction factor for a finite plate. The fatigue crack growth law of surface cracks, depending on the maximum Kmax as well as the range ΔK of the stress intensity factor, has been obtained from fatigue tests under various mean stresses. The effect of tensile residual stress distribution on the fatigue crack propagation rate of surface pre-cracks has been found to be quantitatively evaluated by the use of the proposed fatigue crack growth law, in which Kmax was calculated from the maximum stress distribution including residual and applied stresses. Also, the shape of surface fatigue cracks has been found to be dependent on the residual stress distribution.
