Experimental study on the sensitivity of DMLS manufactured Maraging Steel fatigue strength to the build orientation and allowance for machining

This work derives its motivations from the increasing interest towards Additive Manufacturing and the lack of studies, mainly in the field of fatigue. The effect of build orientation and of allowance for machining on DMLS produced Maraging Steel MS1 has been assessed. The experimental results, properly set up by tools of Design of Experiment, have been statistically processed and compared. The outcomes were that, probably due to effect of the thermal treatment, machining and material properties, the aforementioned factors do not have a significant impact on the fatigue response. This made it possible to work out a global curve that accounts for all the results, consisting in a high amount of data points. This can be regarded as one of the most generable and reliable fatigue models being currently available in the literature. Fracture surfaces have been carefully studied as well, individuating the initiation points being usually located at sub-surface porosities. Micrographies along the stacking direction and the build plane have been performed as well.