The Effect of Heat Treatment on the Fatigue Strength of Ti-6A1-4V

Summary

An investigation has been carried out to determine the type of heat treatment likely to be most successful in increasing the fatigue strength of Ti-6A1-4V. One heat treatment only was successful, namely a solutionising and ageing treatment, which gave a microstructure of small primary α grains in a matrix of stable transformed β. It is concluded that only limited improvements in the fatigue strength of Ti-6A1-4V can be achieved by heat treatment alone, and that such treatments should be carefully controlled because of the possibility of introducing deleterious effects such as a large prior β grain size. The maximum increase in low cycle fatigue strength was obtained when the microstructure contained a high proportion of transformed β, but, unfortunately, such a microstructure did not similarly improve the high cycle fatigue properties.