Static and Cyclic Creep Properties of Ti-6Al-4V for Several Heat Treatments.
GEORGE WASHINGTON UNIV WASHINGTON D C INST FOR THE STUDY OF FATIGUE FRACTURE AND STRUCTURAL RELIABILITY
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The room temperature static and cyclic creep properties were determined for Ti-6Al-4V in three anneal conditions alpha beta anneal, beta anneal and recrystallized anneal. The static and cyclic creep strains were inversely related to microstructure. The beta annealed alloy has the smallest static creep strain and the largest cyclic creep strain the recrystallized anneal alloy has the largest static creep and the smallest cyclic creep. This behaviour indicates that static creep and cyclic creep are a result of different mechanisms. It is proposed that the static creep is a result of dislocation motion within the grains, and the dislocation motion is impeded by phase and grain boundaries to limit static creep strains. The cyclic creep deformation appears to be localized at the grain and phase boundaires. It is proposed that in cyclic creep the dislocations migrate to the strong boundaries and then move back and forth under the cyclic loading producing vacancies at jog sites during each cycle. The vacancies condense into microcracks that are observed after etching.
- Metallurgy and Metallography