A NOTE ON THE INFLUENCE OF REST PERIODS ON THE FATIGUE ENDURANCE OF A TITANIUM ALLOY

S‐N curves have been determined for continuous cycling and for interrupted cycling using commercial purity titanium, and also a Ti‐6Al‐4V alloy in four different states of heat treatment. The incorporation of rest periods during the fatigue tests resulted in increased lives to fracture to an extent which appeared to be independent of specimen composition or microstructure, and hence primarily a function of the titanium itself. Failures from internal crack origins were found at longer lives from some specimens for both continuous and interrupted tests. It is suggested that the observed effects are due to localised hardening and strain ageing as a consequence of oxygen and/or nitrogen pick‐up from the testing environment, and also as a result of oxygen and/or nitrogen present in the starting material. Copyright © 1984, Wiley Blackwell. All rights reserve