The dominant role of defects on fatigue behaviour of a SLM Ni-based superalloy at elevated temperature

This research investigates the impact of defects on the fatigue properties of a selective laser melted Ni-based superalloy at elevated temperatures. Results show that 78.6% of the fatigue failures are initiated by defects, with a larger scatter in fatigue life at lower stress levels. And the coalescence and growth of defects are captured by X-ray computed tomography (XCT). Besides, a quantitative analysis indicates that the fatigue life increases with defect location but decreases with defect size, which is influenced by defect shape. A modified stress intensity range, & UDelta;KL, is proposed, considering the effect of the three factors. Statistical characterization shows larger extreme values for critical defects compared to XCT observation.