NOTCH FATIGUE CRACK INITIATION IN HIGH-TEMPERATURE WATER ENVIRONMENTS - EXPERIMENTS AND LIFE PREDICTION

Test results, experimental techniques and analytical interpretations are reported from notched compact type tests of SA 333 Gr. 6 carbon steel to determine quantitatively fatigue initiation lives in high temperature oxygenated water. Parameters explored include environments of air, 0. 2 ppm O//2 and 8 ppm O//2-water at 10. 3 MPa (1500 psi), temperatures of 149, 232 and 288 degree C, frequencies of 0. 00021, 0. 0021 and 0. 021 Hz, notch radii of 0. 051 and 0. 51 mm and R-values of 0. 2, 0. 5 and 0. 8. Pseudostress amplitudes were calculated elastically and by Neuber notch analysis procedures using a worst case notch concept. Results were compared to ASME Section III fatigue data curves.