Effect of heat treatment on microstructure and mechanical properties of titanium recycled by severe plastic deformation

Abstract

Commercially pure (CP) Ti and Ti-6A1-4V machining chips, recycled into fully dense bulk material by a solid-state process based on equal channel angular pressing (ECAP),have been heat-treated and their microstructure and mechanical properties investigated. The as-recycled micro-structure consisted of an ultrafine grain structure and a series of oxide layers associated with the boundary of each machining chip. Following heat treatment within the range 700 to 1000°C for between 1 and 20 hours, the grain structure coarsened and the oxide was observed to dissolve into Ti solid solution. The solid-state dissolution of Ti oxide is discussed, and the mechanical properties of the heat-treated materi..