Abstract
To obtain the fatigue properties at stress concentration region of Ni-based single crystal superalloy at high temperature, the fatigue tests of notched round bar specimens with notch radii of R0.35mm and R0.06mm were conducted at 650℃. Then the fatigue life of notched round bar specimen with notch radius of R0.1mm was predicted using the theory of critical distance. The calibration method was employed to determine the critical distance. In this study, as the calibration method the stress distributions in the vicinity of the notch tips obtained from FE-analysis for each notched specimens were used. And the critical distance stress was determined as the averaged stress from the notch tip to the critical distance. Then the relationship of the critical distance stress and the fatigue life, which is independent of notch sizes, was obtained. This relationship was used to predict the fatigue life of notched round bar specimen with notch radius of R0.1mm. The predicted life relatively agreed with the experimental one. And the scattering was within a factor of two.
