Modification of Sintered Titanium alloys by Hot Isostatic Pressing

Proceedings of: Powder Processing, Consolidation and Metallurgy of Titanium (PM Titanium 2011). Brisbane, 05-07 December 2011.Powder metallurgy (PM) permits to obtain titanium alloys with properties and microstructures close to ingot metallurgy products. However, residual porosity is normally present in the products produced by the PM route of powder pressing and sintering (P&S)\, and this needs to be reduced by using post-sintering process step such as hot isostatic pressing (HIP) and forging. In this study, the microstructural and mechanical property changes caused by HIP of samples of two alloys, near-alfa Ti-3Al-2.5V alloy and alfa+beta Ti-6Al-4V, produced by P&S route were investigated. Two types of powders were utilised: prealloyed powders and blend of elemental titanium powder and master alloy powder. Four conditions defined by HIP temperature, pressure and time were used to HIP the sintered samples with two geometries. The results show that, independent of the HIP conditions used, HIP increased the relative density of the samples to approximately 97.5% and their hardness by 30-50 HV depending on the HIP condition. However, HIP at 1000ºC changes the fracture mode of the sintered samples from ductile to brittle.The authors are thankful for the financial support from the Spanish Ministry of Education through the R&D MAT2009-14448-C02-02 and MAT2009-14547-C02-02 Projects and from Comunidad de Madrid through the ESTRUMAT (S-2009/MAT-1585) project.Publicad