Bending fatigue life characterisation of direct metal laser sintering nickel alloy 718

Bending fatigue behaviour of direct metal laser sintering (DMLS), Nickel (Ni) Alloy 718 has been assessed as preliminary qualification to additively manufacture advanced gas turbine engine components. Motivation for this work comes from the possibility of using DMLS to improve functionality of hot-section components. By using DMLS, turbine blades and heat exchangers cooling passages can be enhanced, leading to improved engine performance. This study focuses on vibratory high cycle fatigue (HCF) assessment of DMLS Ni Alloy 718 from two suppliers. Specimens were fatigued via vibration-based bending and compared with published rotating bending cold-rolled Ni Alloy 718. Tensile analysis and microscopy were also conducted to understand fatigue and fracture trends. HCF, tensile properties and microscopy comparisons show that fatigue and strength of DMLS Ni may be sensitive to post-fusion treatments. Nonetheless, fatigue performance of DMLS Ni compares well with rotating bending fatigue of cold-rolled Ni.