電子ビーム溶融法により造形したTi-6Al-4V合金のねじり疲労特性評価

抄録

Recently, the application of custom-made implant which can fit to the skeleton and the bony substance of the patient is requested. Then, the way of making custom-made implant by additive manufacturing (AM) is remarked. In this study, we evaluated the torsional fatigue property of Ti-6Al-4V alloy made by electron beam melting (EBM) which is one of AM. The microstructure, analyzed by SEM, consists in fine α+β phase. The higher this observation position of EBM product is, the finer this microstructure is because of keeping more heat of dissolution at the bottom. From the result of torsional fatigue test and the fracture surface observation, it was revealed that the EBM specimens have two types of fracture surface morphology. In the case of one fracture surface, when the internal defects influence the crack initiation, the number of cycle to failure is approximately equal regardless of the build position. On the other hand, in the case of another fracture surface, when the internal defects don't influence the crack initiation, a trend is seen in that the number of cycle to failure decreases upper, middle and bottom specimens in that order.