Bending fatigue behaviour of 17-4 PH gears produced via selective laser melting

The possibility of producing parts via the addition of material, instead of its removing, given by Additive Manufacturing (AM) processes is changing the way in which parts are designed. However, the design of some mechanical components like gears, for instance, requires specific resistance data that, up to now, are not presented in literature. This paper presents a research project aimed at investigating the bending fatigue properties of 17-4 PH steel applied to gears produced via selective laser melting. Single Tooth bending Fatigue (STF) tests were conducted in order to investigate the S-N curve. Results are presented in terms of tooth root stress calculated according to the ISO standard in order to compare them with data of other materials. In addition, Scanning Electron Microscopy (SEM) of the fractured surfaces has been performed on the failed teeth to investigate failure origin and therefore to find causes of tooth breakage.