The growth of corner cracks by fatigue

Room temperature fatigue crack growth rates in Ti-6Al-4V and Ti-5331S have been determined using corner notched test pieces consisting of tensile loaded bars containing a single small quarter-circular crack. The loadings employed involve both major and minor stress cycles which were applied separately or in combination. The measured crack growth rates have been compared with those generated using compact tension test pieces. The expectation that the fatigue crack growth rates in corner notched specimens would be less than those in compact tension specimens was realised in the single case of Ti-6Al-4V subjected to a major cycle only loading. There was no significant difference in the growth rates in compact tension or corner notched test pieces for tests involving either Ti-5331S or combinations of major and minor stress cycles. These results may be rationalised in terms of the crack closure behaviour associated with the different combinations of specimen, material and loadings under investigation. (C) 1997 Elsevier Science Limited.