INFLUENCE OF ENVIRONMENT AND TEMPERATURE ON MEAN STRESS EFFECT IN THE NEAR-THRESHOLD FATIGUE CRACK PROPAGATION BEHAVIOR OF Ti6246 ALLOY

摘要

The present paper is addressing a study of the cracking behavior of a Ti6246 alloy under cyclic loading superimposed to different levels of mean stress, with a special attention to the near threshold fatigue crack propagation regime, and to possible coupled effects of fatigue-corrosion and creep. Tests were conducted at room temperature and 500°C in air, high vacuum and in humidified Argon. The conditions for the occurrence of an abnormal behavior consisting in the disappearance of the threshold for sufficiently high K_(max) level, are discussed in comparison with similar behavior described in the literature at room temperature on several other Ti alloys. The possible involved mechanisms are discussed through micro-fractographic observations.