The intention of this thesis is to investigate the fatigue behavior of the Ti-6Al-4V alloy

manufactured by the relatively new additive manufacturing process called Selective Laser Melting(SLM). SLM

has been shown the interest from important industries such as the aerospace and biomedical industry for its

potential of manufacturing lightweight and complex parts to net shape without the need of conventional

methods like machining.

Due to the short history of SLM there is little knowledge about how fatigue properties are

influenced by the manufacturing process. This project aims to add to that knowledge by studying

how the microstructure, surface roughness and surface morphology influences the fatigue life of

SLM made Ti-6Al-4V alloys. Fatigue tests are done by conducting 3-point bending tests on SLM

and conventional samples.

It was found that the SLM samples only managed 9% of the fatigue life obtained for conventional

samples. This was assumed to be caused by the poor surface roughness of SLM samples, acting as

stress concentrations resulting in multiple crack nucleation leading to final fracture. It was also

found that a surface morphology of 90°, relative to the length of the sample, had worse fatigue life

compared to 60° and 30° due to the pattern of the sample being perpendicular to the applied load.