Very high cycle fatigue characterization of additive manufactured Ti-6Al-4V alloys
                                    Md Mehide Hasan Tusher
A wide range of industries rely on the laser powder bed fusion (L-PBF) technique to produce intricate structures. The Ti-6Al-4V alloy has recently gained a lot of popularity due to its excellent properties in the manufacture of components by L-PBF technology. It is necessary to consider the fatigue performance of L-PBF-Ti-6Al-4V alloy in very high cycle fatigue regime (VHCF) so that the alloy can achieve a wide range of success in various different fields in the future. A study is conducted to examine the effects of stress-relieved (SR) heat treatment on the very high cycle fatigue (VHCF) performance of L-PBF -Ti-6Al-4V alloy in this investigation. There are many factors that can affect the response of the VHCF of L-PBF-Ti-6Al-4V alloy, and this study aims to identify key factors that have a significant influence on the VHCF response of this alloy by combining controlled platform temperatures with stress-relieved heat treatment. To accomplish this, experiments were conducted on Ti-6Al-4V alloy samples manufactured on a substrate with a temperature of 80°C. These samples were subjected to Ultrasonic fatigue testing machine, applying a fully tension-compression load (R= -1). To examine the fractured surfaces of the specimens, a Hitachi Regulus 8230 Scanning Electron Microscopy (SEM) was employed, enabling the analysis of crack-initiating features such as their nature, size, and location. Additionally, in order to identify any defect resulting from the manufacturing process, printed samples were inspected using an XT H225 X-ray μ-CT system (Nikon, MI, USA), allowing computed tomography (CT) observations on the gage sections of the samples.