Differences in wear rate, morphology of the worn surface and debris, and the microstructure in subsurface of the Ti 6Al 4V alloy after wear in air and vacuum were compared. The wear rate of Ti 6Al 4V alloy in air is h...Differences in wear rate, morphology of the worn surface and debris, and the microstructure in subsurface of the Ti 6Al 4V alloy after wear in air and vacuum were compared. The wear rate of Ti 6Al 4V alloy in air is higher than that in vacuum in all the ranges of sliding velocities and applied loads. The wear of Ti 6Al 4V alloy in air is controlled by a combination of abrasion, oxidation and delamination with micro cracks remaining in subsurface. Under the vacuum condition, the surface layer of Ti 6Al 4V alloy experiences a severe plastic deformation on a great scale, which results in an ultra fine microstructure.展开更多
JOHNSON-COOK(J-C) model was used to calculate flow shear stress—shear strain curve for Ti-6Al-4V in dynamic torsion test. The predicted curve was compared with experimental result. Gradient-dependent plasticity(GDP) ...JOHNSON-COOK(J-C) model was used to calculate flow shear stress—shear strain curve for Ti-6Al-4V in dynamic torsion test. The predicted curve was compared with experimental result. Gradient-dependent plasticity(GDP) was introduced into J-C model and GDP was involved in the measured flow shear stress—shear strain curve, respectively, to calculate the distribution of local total shear deformation(LTSD) in adiabatic shear band(ASB). The predicted LTSDs at different flow shear stresses were compared with experimental measurements. J-C model can well predict the flow shear stress—shear strain curve in strain-hardening stage and in strain-softening stage where flow shear stress slowly decreases. Beyond the occurrence of ASB, with a decrease of flow shear stress, the increase of local plastic shear deformation in ASB is faster than the decrease of elastic shear deformation, leading to more and more apparent shear localization. According to the measured flow shear stress—shear strain curve and GDP, the calculated LTSDs in ASB are lower than experimental results. At earlier stage of ASB, though J-C model overestimates the flow shear stress at the same shear strain, the model can reasonably assess the LTSDs in ASB. According to the measured flow shear stress—shear strain curve and GDP, the calculated local plastic shear strains in ASB agree with experimental results except for the vicinity of shear fracture surface. In the strain-softening stage where flow shear stress sharply decreases, J-C model cannot be used. When flow shear stress decreases to a certain value, shear fracture takes place so that GDP cannot be used.展开更多
The properties and forming process of prealloyed powder metallurgy(PM) Ti-6Al-4V alloy were researched for application of high performance of titanium parts. Hot isostatic press(HIP) technology and two kinds of powder...The properties and forming process of prealloyed powder metallurgy(PM) Ti-6Al-4V alloy were researched for application of high performance of titanium parts. Hot isostatic press(HIP) technology and two kinds of powders were used in the prealloyed processing to get full density material. Tensile properties,impact toughness and fracture toughness of PM Ti-6Al-4V alloy were studied and discussed. The microstructures were examined with optical microscope and the morphologies of powders were observed by SEM. Forming processes were performed to fabricate PM titanium parts. The experiment results show that the prealloyed PM Ti-6Al-4V alloy has same good properties as wrought material and the complex shape PM parts can be near-net-shaped. Some of the parts have been commercially used. This indicates that the prealloyed process should have bright prospects in making high-performance,complex shape and low-cost titanium alloy parts.展开更多
Molybdenum nitride(Mo-N) modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The bacteria adherence property of the Mo-N modified layer on Ti6Al4V alloy on the oral bacteria Streptoc...Molybdenum nitride(Mo-N) modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The bacteria adherence property of the Mo-N modified layer on Ti6Al4V alloy on the oral bacteria Streptococcus Mutans was investigated and compared with that of Ti6Al4V alloy by fluorescence microscopy. The mechanism of the bacteria adherence was discussed. The sample was characterized by X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS) and rough-meter. The results show that the Mo-N modified layer is composed of phase Mo2N(fcc) and Mo2N(tetr). There are Mo 3d,N 1s,C 1s and O 1s in the Mo-N modified layer Ti 2p,O 1s,C 1s,in the Ti6Al4V alloy. The surface roughness(Ra) of Ti6Al4V alloy and the Mo-N modified layer is(0.06±0.01) μm and(0.16±0.01) μm,respectively. The Mo-N modified layer inhibits the bacteria adherence. Mo and N on surface of modified layer play a vital role in inhibiting the bacteria adherence.展开更多
A study on hot extrusion of Ti-6Al-4V using simulations and experiments;Damping characterization of aluminium containing interconnected wire reinforcement using a novel fiequency domain based method;Development of Al-...A study on hot extrusion of Ti-6Al-4V using simulations and experiments;Damping characterization of aluminium containing interconnected wire reinforcement using a novel fiequency domain based method;Development of Al-Si-Mg Alloys reinforced with Boron Carbide Particles;Development of Al-Si-Mg Alloys reinforced with Boron Carbide Particles;展开更多
2D and 3D finite element analysis of a three state forging sequence; A technology for cold forging of helical gear with crowning using elastic deformation of die;[Analysis of the elastic characteristics of forging die...2D and 3D finite element analysis of a three state forging sequence; A technology for cold forging of helical gear with crowning using elastic deformation of die;[Analysis of the elastic characteristics of forging die for the cold forged dimensional accuracy;Comparison of wear resistant MMC and white cast iron; Computer-aided die design for axis-symmetric coldforging products by feature展开更多
文摘Differences in wear rate, morphology of the worn surface and debris, and the microstructure in subsurface of the Ti 6Al 4V alloy after wear in air and vacuum were compared. The wear rate of Ti 6Al 4V alloy in air is higher than that in vacuum in all the ranges of sliding velocities and applied loads. The wear of Ti 6Al 4V alloy in air is controlled by a combination of abrasion, oxidation and delamination with micro cracks remaining in subsurface. Under the vacuum condition, the surface layer of Ti 6Al 4V alloy experiences a severe plastic deformation on a great scale, which results in an ultra fine microstructure.
基金Project(2004F052) supported by the Educational Department of Liaoning Province, China
文摘JOHNSON-COOK(J-C) model was used to calculate flow shear stress—shear strain curve for Ti-6Al-4V in dynamic torsion test. The predicted curve was compared with experimental result. Gradient-dependent plasticity(GDP) was introduced into J-C model and GDP was involved in the measured flow shear stress—shear strain curve, respectively, to calculate the distribution of local total shear deformation(LTSD) in adiabatic shear band(ASB). The predicted LTSDs at different flow shear stresses were compared with experimental measurements. J-C model can well predict the flow shear stress—shear strain curve in strain-hardening stage and in strain-softening stage where flow shear stress slowly decreases. Beyond the occurrence of ASB, with a decrease of flow shear stress, the increase of local plastic shear deformation in ASB is faster than the decrease of elastic shear deformation, leading to more and more apparent shear localization. According to the measured flow shear stress—shear strain curve and GDP, the calculated LTSDs in ASB are lower than experimental results. At earlier stage of ASB, though J-C model overestimates the flow shear stress at the same shear strain, the model can reasonably assess the LTSDs in ASB. According to the measured flow shear stress—shear strain curve and GDP, the calculated local plastic shear strains in ASB agree with experimental results except for the vicinity of shear fracture surface. In the strain-softening stage where flow shear stress sharply decreases, J-C model cannot be used. When flow shear stress decreases to a certain value, shear fracture takes place so that GDP cannot be used.
文摘The properties and forming process of prealloyed powder metallurgy(PM) Ti-6Al-4V alloy were researched for application of high performance of titanium parts. Hot isostatic press(HIP) technology and two kinds of powders were used in the prealloyed processing to get full density material. Tensile properties,impact toughness and fracture toughness of PM Ti-6Al-4V alloy were studied and discussed. The microstructures were examined with optical microscope and the morphologies of powders were observed by SEM. Forming processes were performed to fabricate PM titanium parts. The experiment results show that the prealloyed PM Ti-6Al-4V alloy has same good properties as wrought material and the complex shape PM parts can be near-net-shaped. Some of the parts have been commercially used. This indicates that the prealloyed process should have bright prospects in making high-performance,complex shape and low-cost titanium alloy parts.
基金Project(50501016) supported by the National Natural Science Foundation of Chinaproject(2007AAO3Z521) supported by the National High-tech Research and Development program+1 种基金Projects (20051049, 2006021023) supported by the Natural Science Foundation of Shanxi Province, ChinaProject(2006-27) supported by the Foundation for Young Subjects Leaders in University of Shanxi and Scientific Foundation for Returned Overseas Scholars of Shanxi Province, China
文摘Molybdenum nitride(Mo-N) modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The bacteria adherence property of the Mo-N modified layer on Ti6Al4V alloy on the oral bacteria Streptococcus Mutans was investigated and compared with that of Ti6Al4V alloy by fluorescence microscopy. The mechanism of the bacteria adherence was discussed. The sample was characterized by X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS) and rough-meter. The results show that the Mo-N modified layer is composed of phase Mo2N(fcc) and Mo2N(tetr). There are Mo 3d,N 1s,C 1s and O 1s in the Mo-N modified layer Ti 2p,O 1s,C 1s,in the Ti6Al4V alloy. The surface roughness(Ra) of Ti6Al4V alloy and the Mo-N modified layer is(0.06±0.01) μm and(0.16±0.01) μm,respectively. The Mo-N modified layer inhibits the bacteria adherence. Mo and N on surface of modified layer play a vital role in inhibiting the bacteria adherence.
文摘A study on hot extrusion of Ti-6Al-4V using simulations and experiments;Damping characterization of aluminium containing interconnected wire reinforcement using a novel fiequency domain based method;Development of Al-Si-Mg Alloys reinforced with Boron Carbide Particles;Development of Al-Si-Mg Alloys reinforced with Boron Carbide Particles;
文摘2D and 3D finite element analysis of a three state forging sequence; A technology for cold forging of helical gear with crowning using elastic deformation of die;[Analysis of the elastic characteristics of forging die for the cold forged dimensional accuracy;Comparison of wear resistant MMC and white cast iron; Computer-aided die design for axis-symmetric coldforging products by feature
