Papers by Keyword: Beta Titanium Alloy

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Authors: Xin Hua Wu, Joaquin Del Prado, D. Hu, A. Huang, M.Q. Chu, M.H. Loretto
Abstract: Samples of Ti-15Cr and Ti-15V-3Sn-3Al-3Cr (wt%) containing controlled additions of carbon up to 0.2wt% and different oxygen contents have been quenched and aged at temperatures between 400 and 600°C. Optical, scanning and analytical transmission electron microscopy have been used to characterise the microstructures of the quenched and aged samples. Hardness testing has been used to follow the kinetics and extent of age hardening, which are accelerated in Ccontaining samples. The addition of carbon results in the formation of Ti(CxOy) precipitates which pin grain boundaries in forged samples so that the grain size in the quenched C-containing samples is about a factor of ten less than that in the C-free samples. In the C-free samples coarse grain boundary alpha tends to form, but in the C-containing samples alpha precipitation is more uniform throughout the beta grains. The extent of omega precipitation is very different in the two alloys; the Ti-15Cr alloy forms athermal omega in the as-quenched samples and large omega precipitates are formed on ageing at 400°C. No evidence for omega has been obtained in the Ti-15-3. The hardening responses and microstructural observations are interpreted in terms of the different grain boundary oxygen contents in the C-containing and C-free samples and the different roles of omega and of carbon in the two alloys.
Authors: Héloise Vigié, Aurélie Soula, Bernard Viguier
Abstract: Ti-β21S is a β-metastable titanium alloy, currently used in industries such as aeronautics, because of its cold formability, good mechanical properties at elevated temperature, low density and its strong resistance to oxidation. This alloy is hardened by an α-phase precipitation in the β-matrix. The purpose of the present research is to establish the effect of aging on the microstructure and mechanical properties of Ti-β21S. Different thermal aging tests have been carried out at 600°C and at 650°C for 500 hours in laboratory air. The evolution of the microstructure has been reported after each thermal treatment and associated with room temperature tensile tests results.
Authors: Astrid Lenain, Nicolas Clément, Muriel Véron, Pascal J. Jacques
Authors: Shuji Hanada, T. Ozaki, E. Takahashi, S. Watanabe, Kyosuke Yoshimi, Tadasu Abumiya
Authors: Dong Geun Lee, Cheng Lin Li, Yong Tae Lee
Abstract: One of the disadvantages of β-Ti alloys is rapidgrain coarsening at elevated temperatures due to accelerated diffusion in the βphase region. Microstructural stability of β-Ti alloys would depend on theirability to maintain refined grains or microstructures at high temperatures. Thebeta grain growth kinetics of a newly designed beta titanium alloy has beensystematically investigated in this research. The grain growth exponent (n) value is at the range of 0.1-0.2,about 0.1 at low temperatures and about 0.2 at high temperatures over 950°C. Itis lower than other beta titanium alloys. The reason of lower n values can be investigated in the viewof the solute and the diffusivity in the titanium matrix.
Authors: Won Yong Kim, Han Sol Kim
Abstract: The effect of Ge and oxygen content on microstructural formation and mechanical properties of Ti-Nb alloys were investigated in order to design a desirable Ti based alloy through casting process. Three phase mixtures consisting of bcc-structured β phase, orthorhombic structured α" phase and intermediate ω phase were found depending on Nb, Ge, oxygen content in the present alloy system. The volume fraction of α" phase and ω phase decreased with increasing Ge or oxygen content. This microstructural information may indicate that both Ge and oxygen act to increase the stability of β phase rather than α" phase in metastable β-Ti based alloys prepared by water quenching. Elastic modulus values were sensitive to phase stability of constituent phases.
Authors: Ladislav Kander, Miroslav Greger
Abstract: The Paper Deals with Microstructural and Mechanical Properties Changes during Severe Plastic Deformation Process in Beta Titanium Alloy Used for Hip Implants. Effect of Various Numbers of Passes through ECAP (Equal Chanel Angular Pressing) Die on Microstructure and Properties Have been Evaluated. Comparison between Virgin State Cast Alloy and Alloy after Several Steps of Severe Plastic Deformation Induced by ECAP Technology Have been Carried out. Mechanical Properties Have been Evaluated Using Miniaturized Specimens. from Experimental Work can Be Concluded Positive Effect of ECAP Technology both on Mechanical Properties (yield Stress as well as Tensile Strength) Including Grain Size.
Authors: Satoshi Emura, Xiao Hua Min, Seiichiro Ii, Koichi Tsuchiya
Abstract: Swirly segregation of Mo was introduced in Ti-12 mass% Mo alloys through hot caliber rolling. After isothermal aging of the alloys, ω phase precipitated heterogeneously in the alloys due to the segregation of Mo. The effect of the swirly segregation and isothermal aging condition on room temperature tensile properties of Ti-12Mo alloy was investigated. Tensile strength has been slightly affected by the swirly segregation. However, total elongation has been extremely improved from 4~10 % to around 20 % in the samples with tensile strength of between 1000 and 1100 MPa. Under all aging conditions, samples with the swirly segregation show larger reduction in area.
Authors: Yasunori Harada, Kenzo Fukaura, Kenichiro Mori
Abstract: In the multi-stage deep drawing processes of a beta titanium alloy sheet, the formability has been investigated. The beta titanium alloy sheets have sufficient ductility at room temperature, whereas a seizure tends to occur during deep drawing due to high reactivity with other materials. To prevent the seizure, the beta titanium alloy sheet was treated by oxide coating heating, because the coated sheet was not in direct contact with the die during deep drawing due to the existence of the oxide layer. The blank used was the commercial beta titanium alloy Ti-15V-3Cr-3Sn-3Al. The effect of the coating condition on the formability in the multi-stage deep drawing process was examined. It was found that long drawn cups with a height sixfold that of the diameter were successfully formed by oxide coating heating.
Authors: Hans Jürgen Christ, Peter Schmidt
Abstract: The prediction of the applicability range of beta titanium alloys in hydrogen containing environments and the systematic study of hydrogen effects on the microstructure during heat treatment require reliable information about the hydrogen diffusion coefficient DH in the respective titanium alloy. Up to now the little information available on hydrogen diffusivity in commercial titanium alloys indicates a higher hydrogen diffusion coefficient in beta titanium alloys as compared to alpha and alpha + beta titanium alloys. In the present study, the hydrogen diffusion coefficients were determined systematically by means of electrochemically charging the half length of thin titanium rods and subsequent annealing, thereby enabling hydrogen diffusion. The Matano technique was applied in order to identify any effect of hydrogen concentration on DH. The hydrogen diffusion coefficients determined were correlated with results from microstructure examination applying optical and electron microscopy. Since molybdenum and vanadium are the most important beta-stabilizing alloying elements, binary titanium alloys of the Ti–Mo and the Ti–V systems at various contents of the respective alloying element were systematically studied in addition to commerical beta titanium alloys. The results of the experiments revealed the strong effect of beta stability and phase composition on hydrogen diffusion.
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