Effect of notch orientation and single overload on crack interaction in Ti-6Al-4V alloy

In this study, the effect of notch orientation and a single overload on the fatigue crack propagation behavior of Ti-6Al-4V alloy was investigated. The notches were formed in two different forms: symmetrical and asymmetrical. Two types of fatigue crack propagation tests were applied to the specimens, with constant amplitude and overload. It was determined that the increased notch angle delays the formation of crack at notch tip and causes the crack propagation rate to decrease. In asymmetric notched specimens, crack formation and crack propagation rate vary depending on the notch angle. At the edge where the notch angle is small, the crack is formed in a shorter time and the crack propagation rate is also high. The K-I values decreased with increasing the crack angle, while the K-II values showed only change in the threshold region due to crack angle. The crack growth rate in all specimens decreased with the application of a single overload, and the rate of crack retardation after overload increases with increasing notch angle.