An investigation of short and long fatigue crack growth behavior of Ti-6Al-4V

This gaper presents the results of a study of the effects of positive stres s ratios on the propagation of long and short fatigue cracks in mill anneal ed Ti-6Al-4V. Differences between the long fatigue crack growth rates at po sitive stress ratios (R = K-min/K-max = 0.02-0.8) are attributed largely to the effects of crack closure, Microstructurally short fatigue cracks are s hown to grow at stress intensity factor ranges below the long crack fatigue threshold. Anomalously high fatigue crack growth rates and crack retardati on are also shown to occur in the short crack regime. Differences between t he long and the short crack behavior at low stress ratios are attributed to lower levels of crack closure in the short crack regime. (C) 2000 Elsevier Science S.A. All rights reserved.