Fatigue characterization of Titanium Ti-6Al-4V samples produced by Additive Manufacturing

Abstract

Additive Manufacturing offers real opportunities in Thales, since it enables a flexible and cost-effective production of metallic components directly from a 3D digital data model. The manufacture of the parts, layer by layer, allows building more complex geometries by adding new functionalities or reducing the weight. The products of Thales can be more competitive and attractive.Studying and analysing the mechanical properties of such samples is essential. In order to be able to choose the eligible parts, design these parts and ensure their robustness, it is necessary to understand the static and fatigue behaviour of materials built by Additive Manufacturing and, more particularly, the damaging process regarding the microstructure.Following a first study on the static properties of a Titanium alloy used within Thales, a large set of fatigue tests, including both HCF and LCF, have been performed to evaluate the fatigue performances of Ti-6Al-4V samples built by a powder bed fusion process. The fatigue mechanisms and the obtained lifetimes were compared with more conventional processes (casting, wrought).In this paper, the results of these fatigue tests on Titanium (Ti-6Al-4V) samples will be presented. Different parameters have been compared: building orientation, heat treatment (HIP) and post-machining. The fracture mechanisms have also been analysed by performing a correlation between the microstructure analysis (porosity, metallography) and fractographies. It is shown that fatigue performances depend on the selected parameters but these effects are different, depending on the loading domain (HCF, LCF).