SOME OBSERVATIONS ON INFLUENCE OF OXYGEN CONTENT ON FATIGUE BEHAVIOUR OF ALPHA-TITANIUM

Three α-titanium alloys, designated I.M.I. Titanium 115, 130 and 160 and containing ~0.085, 0.125 and 0.27 wt.% oxygen, respectively, have been fatigued in tension-compression at room temperature. Observations of surfaces and of internal sections of these materials have revealed that the extent of twin formation during cyclic loading decreases with increasing oxygen content. Twin associated surface fatigue damage predominates in the Ti 115 but a changeover to slip band crack nucleation occurs in the Ti 160. Internal fatigue damage associated with twins occurs in the Ti 115 and to a lesser extent in the Ti 130, but not in the Ti 160. The occurrence of this internal damage leads to a more shallow S-N curve than in cases where no internal damage is formed. © 1969.