Ti-6Al-4V合金三次元積層造形材の疲労強度に及ぼす表面粗さの影響

抄録

In this study, the effects of surface roughness in additive manufactured Ti-6Al-4V alloy on fatigue strength were investigated. Fatigue specimens with as-build surface (as-build specimens) were manufactured using ARCAM Q20 Electron Beam Melting Machine. Fatigue tests and observations of fracture surfaces on HIP'd (Hot isostatic pressed) and Non-HIP'd as-build specimens were conducted. Fatigue lives of as-build specimens were shorter than those of reference data for specimens with machined surface. There were almost no differences between fatigue lives of HIP'd and Non-HIP'd as-build specimens. Porosities were observed on fracture surfaces of Non-HIP'd as-build specimens. On the other hand, there were no porosities on fracture surfaces of HIP'd specimens. Regardless of presence of porosities, fatigue cracks initiated from surfaces of the HIP'd and Non-HIP'd as-build specimens. Therefore, the surface roughness was more sensitive to the fatigue crack initiation than porosities and HIP did not improve the fatigue life of as-build specimen.