THE EFFECT OF MICROSTRUCTURE AND HIP PROCESS ON THE RESULTING PROPERTIES OF ADDITIVE MANUFACTURED TITANIUM ALLOYS

The additive manufactured (AM) titanium alloys that are produced by powder bed fusion process show different mechanical properties compared to the conventional wrought alloys. This behavior is influenced by the presence of a newly micro-structure and some typical defects originating from the of powder bed fusion process. Since the ductility and the fatigue properties are a critical factor in aerospace parts, special emphasis is given to understand the microstructure for improving the mechanical properties. The objective of this research is to study the effect of the micro-structure changes on the resulted mechanical properties, ductility and fatigue, of Ti-6Al-4V during the AM process. The specimens were broken by tensile and fatigue tests and were characterized in the fractographic and metallographic forms, using optical microscopy, scanning electron microscopy (LV-SEM), energy dispersive X-ray spectroscopy (EDS) and hardness tests. Some of the AM specimens underwent HIP process before the mechanical testing and the results were compared with the no-treated AM specimens. The microstructure and the severity of the defects were classified according to the degree of importance on the ductility and the fatigue strength.