Mechanical Properties of Annealed and Martensitic Ti-6Al-4V. (A.) Microstructure of Solution Treated Ti-6Al-4V. (B.) A Study of Fatigue Damage with Ultrasonic Internal Friction Measurements. (C.).

摘要

Fatigue life studies are reported on annealed microstructures and on solution treated plus quenched microstructures, and it was found that specimens solution treated at about 900 C (1650 F) had the longest fatigue life, longer by at least a factor of four. The microstructure of solution treated and quenched Ti-6Al-4V is reported with particular emphasis on the solution temperature of 900 C (1650 F). It is proposed that it is the strain induced transformation of retained beta phase to martensite that is producing the improved fatigue life of this alloy. Internal friction measurements using a resonance technique at kilohertz (17650 Hz) frequency were made on Ti-6Al-4V that had been subject to cyclic fatigue loading. The measurements showed that the internal friction increased as the fatigue damage was increased.