Papers by Keyword: Ti-6Al-4V Powder

Abstract: Ti-6Al-4V powder, produced by the hydride-dehydride (HDH) process, was hot isostatically pressed (HIP) into three bars. The 10 cm (4 in) diameter bars were hot worked (HW) to three different diameters: 5.1 cm (2 in) (75% reduction in area), 3.8 cm (1.5 in) (86% reduction in area), and 2.5 cm (1 in) (94% reduction in area). Three samples were machined out of each bar along the end, middle and transverse orientations. These samples were ground, polished, and etched. The microstructure of the samples was evaluated at 100X and 200X magnifications. The objective of this experiment was to examine the effect of deformation on the microstructure and properties of hot rolled titanium alloy bar product. Charpy impact samples were also machined out of each of the various diameter bars. Impact testing was used to quantify toughness by correlating the microstructure to the energy absorbed. The tensile properties of the hot bars were determined as well as the crystallographic texture. Scanning electron microscopy (SEM) was performed on the fractured surface of the Charpy impact samples.

Abstract: Ti-6Al-4V compact bulk was fabricated by Spark plasma sintering (SPS) with initial pressure of 1.7 MPa, holding pressure of 50 MPa, heating rate of 100 °C/min, and holding time of 5 min at different sintering temperature. The fracture morphology of the specimen sintered at different temperatures was observed to investigate the sintering mechanism. It can be concluded that there are four stages in the SPS process: activation and rearrangement of particles, connection of particles, growth of sintering neck and bulk deformation. The high-quality bulk compact can be obtained when the above mentioned four sintering stages proceed in turn and are all fully completed. The compact bulk has the best mechanical properties when the sintering temperature was 1050°C. The relative density of the bulk Ti-6Al-4V exceeds 99.5%. The tensile strength and the elongation of Ti-6Al-4V obtained by SPS process are 901 MPa and 13.9%, respectively.

Abstract: Powder metallurgy is widely used to produce alloys with low cost of production. The main drawback using powders is the level of residual porosity of final product which often implies the application of a complicated and costly hot isostatic pressing process. However, this issue can be overcome by using equal channel angular pressing (ECAE) with back pressure (BP). The use of severe shear deformation, with imposed hydrostatic pressure, allows a reduction in the range of compaction temperatures compare to those used in conventional practice. The compaction of Ti-6Al-4V powder by the ECAE method has been investigated. The compaction has been performed at temperatures starting from room temperature (RT) and increasing up to 400°C with various back pressures ranging from 0 to 350MPa. A billet processed by ECAE with 43MPa back-pressure at 400°C was found to have improved relative density of 97.5% and increased Vickers hardness of 369HV, compared to values of 96.7% and 325HV respectively obtained at RT. A relative density of 98.2% and 426HV hardness were measured for billets processed with BP = 262MPa at 400°C. A fully compact billet was obtained by applying 350 MPa of BP at 400°C.