The Tensile Mechanical Properties of Thermomechanically Consolidated Titanium at Different Strain Rates

Abstract

The microstructures, tensile mechanical properties, and fracture behavior of a commercially pure (CP) titanium disk (called PF/Ti disk) and a CP titanium bar (called PE/Ti bar) made by powder compact forging (PCF) and powder compact extrusion (PCE) respectively have been studied. With increasing the strain rate from 10 À4 to 10 À1 s À1 , the yield strength of the PF/Ti disk and PE/Ti bar increased from 708 to 811 MPa and from 672 to 764 MPa, respectively; their UTS increased from 824 to 1009 MPa and from 809 to 926 MPa, respectively, and their elongation to fracture decreased from 21 to 8 pct and from 25 to 17.8 pct, respectively. With a low strain rate of 10 À4 s À1 , the PF/Ti disk did not show any cavities at unbonded or weakly bonded interparticle boundaries, but the PE/Ti bar showed a small number of cavities with sizes of around 1 lm. With a high strain rate of 10 À2 s À1 , the PF/Ti disk showed a small number of cavities with sizes in the range of 0.1 to 0.5 lm, while for the PE/Ti bar, the cavities grew into microcracks of up to 20 lm long. The findings suggest that close to 100 pct of consolidation is rapidly achieved by PCF at 1573 K (1300°C) and PCE at 1523 K (1250°C), respectively, possibly due to the dissolution of the particle oxide surface films during heating and rapid diffusion bonding between the fresh particle surfaces during PCF and PCE.

Carbon Nanotubes Enabled Laser 3D Printing of High-Performance Titanium with Highly Concentrated Reinforcement

“…A great balance between strength and ductility is achieved via laser-tailored formation of nanoscale reinforcement and interfacial regulation. Our approach hopefully broadens the structural applications of CNTs, whose worldwide production capacity has exceeded several (Herzog et al, 2016;Wysocki et al, 2017;Zhang et al, 2008), conventional coarse-grained Ti processed by casting and forging (yellow region) (Koike et al, 2011;Stolyarov et al, 2001;Xu and Zhu, 2012;Niinomi, 1998;Reshadi et al, 2017;Figueiredo et al, 2014;Zhao et al, 2010;Zinelis, 2000), Ti strengthened through plastic deformation with the formation of nanostructure (blue region) (Gunderov et al, 2013;Liang et al, 2015). The error bar of each experimental datum from our work is depicted in Figure S5…”

“…Figure5. Tensile Properties of Laser 3D-Printed In Situ Ti-Based Nanocomposite Parts (A) A summary of tensile strength versus fracture elongation of Ti processed by various methods, including our work (red region), laser additive manufactured Ti with refined microstructure (purple region)(Herzog et al, 2016;Wysocki et al, 2017;Zhang et al, 2008), conventional coarse-grained Ti processed by casting and forging (yellow region)(Koike et al, 2011;Stolyarov et al, 2001;Xu and Zhu, 2012;Niinomi, 1998;Reshadi et al, 2017;Figueiredo et al, 2014;Zhao et al, 2010;Zinelis, 2000), Ti strengthened through plastic deformation with the formation of nanostructure (blue region)(Gunderov et al, 2013;Liang et al, 2015). The error bar of each experimental datum from our work is depicted in FigureS5.…”