Effect of prestrain on the fatigue properties of Ti834

The effects of cold dwell on titanium alloys have been widely studied in recent years, with many alloys showing detrimental mechanical properties when dwell periods are introduced at peak load. Failures in such situations are often characterised by the formation of quasi-cleavage facets, and models have been suggested to explain the mechanism by which they occur. This paper seeks to investigate how different mechanical test regimes influence facet formation. It is shown in the titanium alloy Ti834 that facet formation occurs readily under stress relaxation and creep loading, but is less influenced by cyclic strain control loading. The implications of this type of strain accumulation process on the mechanical properties of Ti834 are discussed, with close correlation between suggested models and experimental data.