The relationship of axial strain induced by cyclic torsion to metal stability and fatigue failure in Ti-6A1-4V
✍ Scribed by C.M. Gilmore; M. Freedman; M.A. Imam
- Publisher
- Elsevier Science
- Year
- 1976
- Tongue
- English
- Weight
- 845 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
The alloy Ti-6Al4V was cycled with reversed torsional strains. The torsional strain amplitudes were all below the yield strain (pseudoelastic fatigue); therefore, plastic deformation is small and the conventional techniques for studying fatigue in plastic metals are ineffective. However, it was observed that the second ordet axial strain accumulation "Ronay effect" can be used to monitor the metal during fatigue. At a torsional strain amplitude of about ~040.5, the axial strain accumulation began to increase rapidly. It was observed that the cycles to failure vs strain amplitude curve changes from (S) type to (H) type at strains of about 0405. The axial strain accumulation and the knee of the fatigue life curve appear to be related. The observed results are explained by assum~g #at the knee, which occurs at strains well below yield, results from inelastic deformation at the grain and phase boundaries. A test with a single specimen showed that the point of increasing axial strain accumulation couId also be Iocated by continually increasing the torsional strain amplitude.