The Relationship of Axial Strain Induced by Cyclic Torsion to Metal Stability and Fatigue Failure in Ti-6Al-4V.
GEORGE WASHINGTON UNIV WASHINGTON D C INST FOR THE STUDY OF FATIGUE FRACTURE AND STRUCTURAL RELIABILITY
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The response was studied of the alloy Ti-6Al-4V to reversed cyclic torsional fatigue loading. The torsional strain amplitudes were all below the yield strain psuedoelastic fatigue therefore, plastic deformation is small and the conventional techniques for studying fatigue in plastic metals are ineffective. A technique for studying the response of the metal that is based upon the Ronay effect was applied to the study of psuedoelastic fatigue in Ti-6Al-4V. The application of the technique showed that there was a metal instability at torsional strains of approximately plus or minus 0.0055. Other related observations that indicate an instability at this strain are the occurrence of creep steps during dead loading, and it was also observed that the cycles to failure vs strain amplitude curve changes from S type to H type at this strain amplitude.
- Metallurgy and Metallography