Characterization of Defects and Fatigue Behavior of Ti600 Alloy Rod Synthesized by Selective Laser Melting

A rod(Φ20 mm×80 mm)of Ti600 alloy,an advanced material of aircraft internal combustion engine,was synthesized by selective laser melting of constituent powders in argon atmosphere.The fatigue behavior,microstructures/distributions/growth of cracks at fatigue fractures were characterized with scanning electron microscopy and quasi-in-situ fatigue test and numerical calculation.The preliminary results show that when it comes to defects smaller than 50 μm and most distributing in 12~35 μm range,the defect frequency was 86%;and that the normally distributed defect-sphericity was lower than 0.95,basically in 0.4~0.64 range,and its dispersion increased with an increasing equivalent diameter.In high-cycle-fatigue(HCF)test,three well-defined microstructures,including the crack-source,propagation of surface crack,and flat semi-elliptical fracture,were observed.Moreover,fairly large pores and non-fused powders were found to dominate the fractured surfaces.