Structural engineer, Lloyd's Register of Shipping, London,
Reader, Imperial College of Science and Technology, London,
Pages: 15 Published: Jan 1988
An investigation was conducted into fatigue crack growth in samples of as-received and autofrettaged, high-strength, low-alloy steel tubing containing residual stresses. Compact tension and C-shaped and ring specimens were used to measure properties in the axial and radial directions. Internally and externally flawed ring specimens were employed to propagate cracks through the original residual stress field. Experiments were performed for load ratios ranging between -0.5 and 0.8. Fatigue crack growth rates were substantially reduced by compressive residual stresses. The data were corrected for residual stress effects using the superposition principle. An effective stress intensity factor range, ΔKeff, was defined that incorporates the residual stress intensity factor, Kres, and the applied ΔK range. Using this approach, the correlation with the characteristics for no residual stress was very good. In addition, it was shown that fatigue crack growth rate characteristics measured with C-specimens can significantly misrepresent the actual behavior of the material and tubing under investigation if the remaining residual stress field is not taken into consideration.
fatigue crack growth, residual stress distributions, autofrettage, linear-elastic fracture mechanics, superposition, effective stress intensity factor range, effective load ratio
Paper ID: STP17176S