Low Cycle Notched Fatigue Behavior and Life Predictions of A723 High StrengthSteels

摘要

Two types of ASTM A723 steels have been investigated for their low cycle fatigue behavior (less than l% cycles to failure). Specimens were tested in four-point bending, both with and without notches, and the measured fatigue lives were compared with those predicted by Neuber notch analysis (classic and elastic/plastic remote applied loading), and standard fracture mechanics life prediction techniques. Comparison of measured and predicted lives indicates that the elastic/plastic Neuber analysis underpredicts the measured fatigue life by as much as 6% percent at large strains, and becomes a better predictor of life as the applied strains decrease. The elastic Neuber analysis also underpredicts the measured fatigue lives by 45 percent at large applied strains, but seems to accurately predict lives at reversals-to-failure greater than 100. The fracture mechanics approach assumes elastic stresses at the crack tip, and predicts lives within 30 percent over the full range of strains investigated.