Microstructure and mechanical properties of hot isostatically pressed Ti-6Al-4V alloy

We report the microstructural analysis and mechanical characterization of Ti-6Al-4V alloy parts fabricated using hot isostatic pressing (HIP). Prealloyed powders were manufactured via gas atomization (G/A), plasma atomization (P/A), and the hydride/dehydride (HDH) processes, and were characterized and pressed at temperatures in the range 880-980 degrees C. The microstructure of the specimens was found to be strongly dependent on the beta-transus temperatures. The G/A and P/A powders were pressed at temperatures above and below the transus temperature to enable comparison of the alpha-beta and beta microstructures. An alpha-beta mixed phase in the specimens that underwent HIP from HDH powders was observed, regardless of the pressing temperature because the temperature was always below the beta-transus temperature. The billets formed from the atomized powders exhibited higher tensile strength and ductility than the billets produced from the HDH powder. The specimens consolidated from the HDH powder showed brittle behavior because of the increased oxygen content and microstructural inhomogeneities. (C) 2014 Elsevier B.V. All rights reserved.