Investigation of the Abnormal Near-Threshold Fatigue Crack Propagation on a Ti6246 Alloy

摘要

This paper deals with a study on a perplexing phenomenon which has been recently reported on several titanium alloys which were found not to exhibit a threshold in ambient air at room temperature or 120°C when tests are run at high mean stress levels and very low stress intensity factor ranges. In such conditions, these materials revealed a stationary regime with a constant growth rate. This paper is devoted to the determination of the factors influencing the occurrence of this phenomenon, including mean stress level, test frequency (35 Hz and 3.5 Hz), temperature (room temperature, 150°C and 500°C) and environment through comparative tests performed in air and in high vacuum.