Axial fatigue behavior of notched Ti-6Al-4V specimens

Ti-6Al-4V is widely applied in the aerospace industry because it offers advantageous specific strength and appreciable resistance to corrosion. Aerospace parts and components are subjected to varying service loads and are typically damaged in operation. In order to ensure structural integrity and durability, the influence of such defects on the behavior of components must be considered [1]. Small cracks propagate very rapidly [2]. The plastic zone at the notch tip affects the crack propagation rate [3]. As the defect size decreases, the maximum stress increases and the gradient becomes steeper [4]. In this work, axial fatigue tests are performed on notched Ti-6Al-4V specimens in inert environment using a step loading procedure [5]. Each load block consists of 200,000 cycles and the load ratio in the fatigue tests is R=0. The elastic stress concentration factors due to the notches are calculated by finite element modelling. Some data and results are shown in Table 1. To identify the failure mechanism, the fracture surfaces of the failed specimens are macroscopically analyzed. Figure 1 shows the fracture surface of the specimen 3 of Table 1.