Influence of microstructure on the fatigue behavior of blended elemental Ti-6AL-4V alloy post-consolidated by extrusion

Abstract

The blended elemental (BE) route is currently the main way for obtaining cost-affordable titanium alloys. Via post-consolidation processes like hot isostatic pressing (HIP) or thermomechanical processing, the material can improve its mechanical properties. In this work, a titanium alloy is processed via the BE approach, combined with thermomechanical processing of the sintered billets and subsequently heat treated. The tensile behavior of the sintered, extruded and heat-treated Ti-6Al-4V alloy was studied, finding an overall improvement of the properties after extrusion and a considerable increase in strength without compromising ductility after heat treatment. The high cycle fatigue behavior of the as-extruded alloy was studied by means of axial testing. There is a strong dependence between the location of the initiation of failure of the alloy and its fatigue life, but the defects that initiated failure were facets, not pores. The fatigue life of the as-extruded alloy is comparable to that of other fully-dense powder metallurgy (PM) and wrought Ti-6Al-4V alloys. These findings encourage the use of this route of processing as a balanced approach between low-cost and high-performance titanium alloys.