Influence of the finish cutting operations on the fatigue performance of Ti-6A1-4V parts produced by Selective Laser Melting

The production of parts by additive manufacturing technologies is a hot topic for industry. The Selective Laser Melting process is among the most widely used nowadays. Unfortunately the geometrical accuracy, as well as the surface roughness are very poor. Functional surfaces therefore require further machining operations in order to fulfill the specifications of the designer. However the influence of finishing operations on the surface integrity of such parts needs to be further investigated. This paper aims at analyzing the influence of milling or polishing operations on the rotary bending fatigue resistance of titanium samples generated by SLM. It is highlighted that finishing operations are able to improve significantly the fatigue resistance compared to the initial state after SLM + heat treatment. The fatigue results are also discussed in light of the surface integrity (roughness parameters and residual stresses). It is found that the surface topography skewness is an interesting parameter which correlates with the fatigue performance. None of these finishing techniques are able to lead to a fatigue resistance comparable to the one obtained with a wrought titanium part. (C) 2018 The Authors. Published by Elsevier Ltd.