Influence of surface quality and porosity on fatigue behaviour of Ti–6Al–4V components processed by MIM

Fatigue and tensile mechanical properties of Ti–6Al–4V alloy processed by metal injection moulding (MIM) technology were evaluated in this investigation. Two critical parameters, binder content of the feedstock and maximum sintering temperature, were studied. Samples sintered at 1350 °C exhibited higher tensile strength than those sintered at 1250 °C. Higher content of binder promoted an increase of the surface quality of MIM components. Consequently, the fatigue endurance limit increased from ∼350 MPa (components with lower binder content) to ∼400 MPa (samples with a higher binder content). Furthermore, reduction of ductility was observed for changing from closed to open porosity; however, the fatigue resistance did not follow the same trend. This is probably due to the fact that better surface quality and smaller grain size compensated the negative influence of porosity on the fatigue behaviour.