Guozhen, China
Guozhen, China

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PubMed | BAOTI Group Ltd, Xiangtan University, Central South University and Nuclear Power Institute of China
Type: | Journal: Materials science & engineering. C, Materials for biological applications | Year: 2016

A biomedical titanium alloy (Ti-7Nb-10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringers solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution phase and the ath formed during athermal process. The ST alloy exhibits Youngs modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as +ath+iso (144 h) at Taging=350-400 C, +ath+iso++ at Taging=500C, and +ath+ at Taging=600-650 C, where iso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4V alloy, the Ti-7Nb-10Mo alloy is more resistant to corrosion in Ringers solution. Results show that the Ti-7Nb-10Mo alloy is promising for biomedical applications.


Zhang W.J.,General Research Institute for Nonferrous Metals, China | Song X.Y.,General Research Institute for Nonferrous Metals, China | Hui S.X.,General Research Institute for Nonferrous Metals, China | Ye W.J.,General Research Institute for Nonferrous Metals, China | And 2 more authors.
Materials Science and Engineering A | Year: 2014

The effect of lamellar α phase (αL) thickness on tensile behavior at 700°C of BTi-6431S titanium alloy is investigated. Two types of bi-modal microstructures are introduced through different heat treatments. Both of them have similar volume fraction of equiaxed α phases (αe). One has thick α lamella named BTL, and another has fine α lamella named BFL. The results show that dynamic recrystallization (DRX) happens in the α phase during tensile process at 700°C. After being deformed at 700°C, the shape of αL in BFL and BTL transforms into sphere. BFL possesses higher tensile strength, and the elongation is twice as large as BTL at 700°C. Compared to the thick αL, the fine αL has more excellent accommodative deformation capability. There are cracks found to be of wedge type located at the grain triple junctions in both BFL and BTL. In addition, some small voids stay at the lamellar boundaries in BTL. In order to acquire a good combination of tensile strength and elongation at 700°C for BTi-6431S alloy, the thickness of αL should be reduced. © 2013 Elsevier B.V.


Honggang M.,Baoti Group Ltd | Kuaishe W.,Xi'an University of Architecture and Technology
Ti 2011 - Proceedings of the 12th World Conference on Titanium | Year: 2012

Friction stir procession for TA2 Commercially Pure Titanium was successfully performed. The microstructure characteristics of stir zone, thermo-mechanically affected zone and heat affected zone were investigated. The wear properties and electrochemistry corrosion resistance contrast between base material and friction stir procession sample was analyzed in detail. The results indicate that the microstructure of stir zone and thermo-mechanically affected zone that stir zone friction stir procession exhibits greatly refined equiaxial grains and obtains the better mechanical performance, stir zone show much better wear resistance when abrasive wear cycles is 1000 r, 1500 r,2000 rthe abrasion loss of stir zone is respectively smaller than base material about 31. 4%>36. 6%,46. 4%. Electrochemistry corrosion resistance of friction stir processing sample has fallen slightly.


Hao W.,BAOTi Group Ltd.
Ti 2011 - Proceedings of the 12th World Conference on Titanium | Year: 2012

Titanium's high strength, low density, excellent flexibility and strong spring-back characteristics, high-temperature performance, good corrosion resistance, and biocompatibility are highly beneficial in developing emerging applications. Titanium emerging applications are developing rapidly in recently years besides traditional aeronautical and aerospace, military, chemical processing applications. The world titanium emerging application market, including automobile, ocean engineering, medical implant, architecture, computer, sports articles, consume goods and geothermal industry are overviewed in the paper, focusing on the automotive industry, marine engineering and medical implant application status. Prospects of emerging market in the future are also discussed in the paper.


Wang X.-X.,Baoti Group Co. | Wang W.-Q.,Baoji Titanium Industry Co. | Zhang Y.-Q.,Baoti Group Co.
Materials Science Forum | Year: 2013

The microstructures of the Alloy C+ with three different heat treatment processes have been investigated after exposure at 550 °C for 100 hours in this study. The alloy shows typical equiaxed β grains with second phase precipitation and twin formation inside the β grains in the as-rolled condition. Solution treatment at lower temperature led to a smaller β grain size while higher temperature solution treatment produced coarse grains with increasing precipitated phases inside the β grains. Ageing treatment after solution and thermal exposure for a long period of time resulted in an increasing α phase precipitation at the grain boundaries due to their tendency for preferential nucleation of second phases. In a certain condition, continuous coarsening of the α phase is concentrated on the grain boundaries therefore violate the properties of the alloy. © (2013) Trans Tech Publications, Switzerland.


Li C.-L.,General Research Institute for Nonferrous Metals, China | Mi X.-J.,General Research Institute for Nonferrous Metals, China | Ye W.-J.,General Research Institute for Nonferrous Metals, China | Hui S.-X.,General Research Institute for Nonferrous Metals, China | And 2 more authors.
Journal of Alloys and Compounds | Year: 2013

A study on the microstructural characteristics and tensile properties of a new high strength Ti-6Cr-5Mo-5V-4Al alloy were investigated. Both the α/β and β solution treatment and subsequent aging at temperatures ranging from 460 °C to 560 °C were introduced to investigate the microstructural characteristics and microstructure-property relationships. The results show that the primary α phase formed during the α/β solution treatment can increase the stability of the β matrix and then restrain the size of secondary α phase during subsequent aging. In the α/β solution plus aging condition, the secondary α phase with the size of about 1 μm results in a high strength above 1500 MPa with -6% of elongation. The β solution treatment leads to the least stable β matrix and the greatest driving force for secondary α phase, so coarser α phases tend to form during aging. The β solution plus aging does not lead to attractive high strength because of the coarser and non-uniform α phase. And it also leads to a poorer combination of strength and ductility than the α/β solution plus aging. Direct aging exhibits the best strengthening. The ultimate strength of the alloy is about 1600 MPa with acceptable elongations of 6.5-7.5% when direct aged at 500 °C for 2-8 h. It benefits from the mixed microstructure with nano-scale and micron-scale α phases. However, more detailed investigations are needed to improve the ductility. As a whole, the alloy can be heat treatable to obtain an excellent balance of strength and ductility, and provide abundant stress levels with optional ductility (900-1600 MPa in ultimate strength and 6-20% in elongation). © 2012 Elsevier B.V. All rights reserved.


Wang X.-X.,Baoti Group Co. | Hui S.-X.,General Research Institute for Nonferrous Metals, China
Materials Science Forum | Year: 2011

Effect of heat treatment on the damage tolerance properties of a newly developed middle strength high damage tolerance Ti-6Al-2Zr-2V-1.5Mo ELI alloy plate has been investigated in this paper by testing fracture toughness and fatigue crack-extending rate of the plate under three heat treatment conditions and fractograph inspection of the samples. It has been found that with the increasing of the primary annealing temperature from 900°C to 950°C, the fracture toughness increased and the fatigue crack extending rate decreased significantly. Microstructural observation has found that the crack expanded through the α beaming and mainly are perpendicular to the α orientation in the lamellar structure which annealed in α+β phase zone. For the Widmanstaten structure, which can be obtained from annealing in single β phase zone, the continuous grain boundary α phase and α beaming boundary hinder the crack expanding significantly. © (2011) Trans Tech Publications.


Jiang H.-T.,University of Science and Technology Beijing | Yan X.-Q.,University of Science and Technology Beijing | Liu J.-X.,Baoti Group Co. | Duan X.-G.,University of Science and Technology Beijing
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

The effect of heat treatment on microstructure and mechanical properties of the Ti-steel explosive-rolling clad plate was elaborated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), micro-hardness test and shear test. The composites were subjected to heat treatment at temperature of 650-950 °C for 60 min. The results show that the heat treatment process results in a great enhancement of diffusion and microstructural transformation. The shear strength decreases as the treatment temperature increases. Heated at 850 °C or below, their shear strength decreases slowly as a result of the formation of TiC in the diffusion interaction layer; while at the temperature of 850 °C or above, the shear strength decreases obviously, which is the consequence of a large amount of Ti-Fe intermetallics (Fe2Ti/FeTi) along with some TiC distributing continuously at diffusion reaction layer. © 2014 The Nonferrous Metals Society of China.


Wang W.,BAOTi Group Ltd | Dong J.,BAOTi Group Ltd
Materials Science Forum | Year: 2011

A special thermomechanical process has been developed in order to improve the homogeneity of the microstructure and mechanical properties of Ti-6Al-4V alloy bar with a diameter of 450 mm for aerospace application. This study has investigated microstructure and mechanical properties on the large diameter bar. It has been found that the heavy section of the bar has uniform microstructure and mechanical properties, which can meet the specifications for Ti-6Al-4V alloy bar with a diameter of 300 mm, and ultrasonic inspection can meet the specification of ASM 2631class A. © (2011) Trans Tech Publications.


Kent D.,Defence Materials Technology Center, Australia | Wang G.,Defence Materials Technology Center, Australia | Wang W.,BaoTi Group Ltd. | Dargusch M.S.,Defence Materials Technology Center, Australia
Materials Science and Engineering A | Year: 2012

A study of the effects of temperature and heating rate upon the ageing response of a Ti-6Cr-5Mo-5V-4Al alloy was undertaken. The degree of strengthening declined with increasing ageing temperature as the precipitate morphologies became coarser, while the extent and thickness of grain boundary α increased with temperature. Ageing at temperatures between 440°C and 500°C result in the greatest age hardening response in times of around 4h due precipitation of the α phase. At 440°C the hardness increases from the initial solution treated value of 275 H V to more than 450 H V. The rate of heating to reach the isothermal ageing temperature has a substantial impact on the ageing response. Greater scatter was observed in hardness results for the samples aged using a faster heating rate at 500°C. For ageing at 560°C a faster rate of heating to the ageing temperature led to rapid declines in the hardness after the peak, equivalent to around 20% of the peak value. Slower heating rates (5°Cmin -1) appear to increase the number of nucleation sites for precipitation of the α phase, forming finer, more even distributions of precipitates. Faster heating rates (∼100°Cmin -1) produce coarser, less evenly distributed precipitates which coarsen more rapidly. © 2011 Elsevier B.V.

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