Fatigue Behaviour of Additively Manufactured Ti-6Al-4 V

Abstract

Fatigue behaviour of Ti-6Al-4V specimens additively-manufactured via Laser Engineered Net Shaping (LENS) is investigated in this study. Additive manufacturing provides the opportunity to fabricate complex geometries layer-by-layer from 3D computer aided drawings. As the mechanical behaviour of metallic materials depends on their microstructure, which is affected by the time-temperature history, additive-manufactured components are expected to have different properties than those of their wrought counterparts. Ti-6Al-4V rods were fabricated by LENS using two different sets of process parameters and machined into ‘dog-bone’ fatigue specimens with dimensions in conformance to ASTM standards. The fatigue behaviour and microstructural features of the LENS Ti-6Al-4V samples were characterized and compared with wrought Ti-6Al-4V. Fractography of the fractured specimen surfaces was performed using Scanning Electron Microscopy (SEM) to determine the failure mechanism and realize the effects of porosity on fatigue resistance and data scatter of LENS Ti-6Al-4V. The fatigue lives of the LENS Ti-6Al-4V materials were found to be lower than those of the wrought Ti-6Al-4V, and driven by the porosity and microstructure of the samples.