Effect of initial microstructure on the processing of titanium using equal channel angular pressing

Equal channel angular pressing (ECAP) is a metal processing technique that is used to produce materials with ultrafine (<1 μm) grain sizes. In this work, the effect of the initial microstructure on ECAP of commercially pure titanium (CP Ti), a material used in many industrial applications, was investigated. To produce different initial microstructures, samples of CP Ti were exposed to different annealing conditions: no annealing (Material 1), annealed at 1033 K for 2 hr (Material 2), or annealed at 1173 K for 4 hr (Material 3). Each material was subjected to one pass of ECAP and the resulting microstructures were analyzed using XRD, SEM, and TEM, and compared to the microstructures before ECAP. It was found that each material developed a unique microstructure after one pass of ECAP, which was attributed to the varying microstructural characteristics before ECAP. Microhardness values before and after ECAP varied with each microstructure.