  Ti-6Al-4V is a titanium alloy with excellent properties for lightweight
applications and its production through Additive Manufacturing processes is
attractive for different industrial sectors. In this work, the influence of
mechanical properties on the notch fracture resistance of Ti-6Al-4V produced by
Selective Laser Melting is numerically investigated. Literature data is used to
inform material behaviour. The as-built brittle behaviour is compared to the
enhanced ductile response after heat treatment (HT) and hot isostatic pressing
(HIP) post-processes. A Phase Field framework is adopted to capture damage
nucleation and propagation from two different notch geometries and a discussion
on the influence of fracture energy and the characteristic length is carried
out. In addition, the influence of oxygen uptake is analysed by reproducing
non-inert atmospheres during HT and HIP, showing that oxygen shifts fracture to
brittle failures due to the formation of an alpha case layer, especially for
the V-notch geometry. Results show that a pure elastic behaviour can be assumed
for the as-built SLM condition, whereas elastic-plastic phenomena must be
modelled for specimens subjected to heat treatment or hot isostatic pressing.
The present brittle Phase Field framework coupled with an elastic-plastic
constitutive analysis is demonstrated to be a robust prediction tool for notch
fracture after different post-processing routes.
