The role of twinning in the fatigue behaviour of α-titanium

Coarse grained (0·3 mm) -titanium has been fatigued in tension-compression about a zero mean load to 100 cycles/sec at normal temperature. Sections through fatigued specimens revealed that twin formation had occurred in grains completely constrained by surrounding material during cyclic loading and that fatigue damage was associated with some of these twins. A micro-beam X-ray and single face sterographic analysis technique combined with metallographic observations of the specimens revealed that {10¯12}, {11¯21} and {11¯22} twins had formed and that the internal fatigue damage was preferentially formed at the twin-matrix interface of the {11¯21} twins.The authors wish to thank Professor G. V. Raynor, F.R.S., for the provision of laboratory facilities. This research has been sponsored in part by the Air Force Materials Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio U.S.A. through the European Office of Aerospace Research under Contract No. F61052.67.C.0007.