Two types of notched specimen of Ti-6Al-4V simulated screw configuration were prepared and cyclic fatigue test was performed in air to study fatigue property of titanium screw. Effect of heat-treatment on fatigue strength was also investigated. As a result, the specimen having a smaller notch diameter showed higher fatigue strength (N_f=10^7) than that of larger one. This result indicates that fatigue strength of notched screw can be organized with its stress concentration factor. Heat-treatment improves tensile and fatigue strength, but, endurance ratio (fatigue strength/tensile strength) become lower compared as-received materials, which supports the idea that heat-treatment affected strongly to the tensile strength not to the fatigue properties.
