Efficient determination of influence factors in fatigue of additive manufactured metals

The additive manufacturing (AM) technology transforms metal powder, layer by layer, into structural components. Sectors such as aerospace and motor racing require: i) in-depth knowledge of mechanical behavior, especially fatigue, of these metals; ii) fatigue data for component design. In the recent years the industrial expectations about metal AM technology have exploded with a focus now on materials and components qualification. Material and AM process qualification costs are high because metal powder and AM system processing time are expensive. The approach adopted in this paper to efficiently generate knowledge on influencing factors of the fatigue behavior of DMLS Ti-6Al4V alloy utilizes non-standard (i.e. miniature) specimens and simple plane bending test machines. After validation of the proposed methodology against test results for the same material obtained with standard specimens, the merit of the innovative approach is demonstrated by presenting original data on the influence of surface quality, heat treatment, coupled material directionality and notch effects on fatigue behaviour of DMLS Ti-6Al4V.