• Title/Summary/Keyword: Beta Ti-alloy

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Aging Treatment Optimization of Ti-3Al-8V-6Cr-4Mo-4Zr Alloy for Spring Application (스프링용 Ti-3Al-8V-6Cr-4Mo-4Zr 타이타늄 합금의 시효열처리 최적화)

  • Youn, Chang-Suk;Park, Yang-Kyun;Kim, Jong-Hyung;Lee, Soo-Chang;Lee, Dong-Geun
    • Journal of the Korean Society for Heat Treatment
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    • v.30 no.6
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    • pp.279-284
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    • 2017
  • Mechanical properties of titanium alloy can be improved by controlling microstructure through heat treatment. In this study, Ti-3Al-8V-6Cr-4Mo-4Zr metastable beta titanium alloy, was controlled for excellent mechanical property and sound formability through various high temperature heat treatment and aging conditions and the optimum heat treatment conditions were determined. The specimens were heat-treated at $950^{\circ}C$, followed by various aging treatments from $430^{\circ}C$ to $500^{\circ}C$ for 1 to 24 h. As aging temperature and holding time increased, hardness increased by ${\beta}^{\prime}$ phase formation and precipitation of secondary ${\alpha}$ phase in ${\beta}$ matrix. However, the optimum aging temperature and holding time for mechanical properties were at $450{\sim}470^{\circ}C$ for 8~16 hr. Hardness values of the specimen aged at $450^{\circ}C$ for 8 h were found to be the highest. These results can be effectively applied to fabrication of spring with better formability and mechanical property.

The Effects of Oxygen Content on Microstructure and Mechanical Properties of Ti-Al-Fe-Si-O alloy (산소함량에 따른 Ti-Al-Fe-Si-O 합금의 기계적 특성 및 미세조직 변화)

  • Bae, Jin Joo;Yeom, Jong Taek;Park, Chan Hee;Hong, Jae Keun;Kim, Senog Woong;Yoon, Seog Young;Lee, Sang Won
    • Journal of the Korean Society for Heat Treatment
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    • v.29 no.6
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    • pp.264-271
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    • 2016
  • The effect of the oxygen content and the annealing temperature on the tensile behavior of the Ti-1.5Al-3Fe-0.25Si-(0.1~0.5)O alloy was investigated. The tensile properties were dependent on the volume fraction of the microstructure constituents, i.e. the equixed ${\alpha}$, equixed ${\beta}$ and lamellar ${\alpha}$. The results showed that the O-partitioned equixed ${\alpha}$ had a much higher strength compared to the equixed ${\beta}$. The strength of the lamellar ${\alpha}$ increased with increasing the annealing temperature because the O content of the lamellar ${\alpha}$ increased. Ti-1.5Al-3Fe-0.25Si-0.3O alloy annealed to $900^{\circ}C$ where the volume fraction of lamellar ${\alpha}$ was the highest exhibited an excellent combination of the strength (1198.5 MPa) and ductility (27.5%). The effect of the lamellar ${\alpha}$ on the ductility was discussed.

A Study on the Characteristics for High Frequency Induction Heating of Ti Alloy Groove Wire (안경테용 Ti 합금 홈선의 고주파유도가열처리에 따른 특성 변화에 관한 연구)

  • Park, Jeong-Sik;Jang, Woo-Yeong;Lee, Jeong-Yeong
    • Journal of Korean Ophthalmic Optics Society
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    • v.12 no.3
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    • pp.55-58
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    • 2007
  • Titanum and its alloys have been used as the important materials of eyewear frame due to its light weight, mechanical strength and corrosion resistance. This study investigates hardness and microstructures of titanum alloy groove wires in according with heating time by high frequency induction heating. Because of increase of grain size by the growth of heating time, hardness of ${\beta}-Ti$ has reduced. Hardness of Ti-325 reduced until 2 sec and rapidly increased at 3 sec by high frequency induction heating. It is observed that hardness of Ti-325 reduces by the increase of the grain size until 2 sec and suddenly increased by the development of the detailed ${\alpha}+{\beta}$ lamella at 3 sec.

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TEM Diffraction Analysis of Metastable Phases in Beta Ti Alloys (베타 티타늄합금의 준 안정상 TEM 회절도형 분석)

  • Choe, Byung Hak;Shim, Jong Heon;Kim, Seung Eon;Hyun, Yong Taek;Park, Chan Hee;Kang, Joo-Hee;Lee, Yong Tai;Kim, Young Ouk
    • Korean Journal of Materials Research
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    • v.25 no.8
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    • pp.403-409
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    • 2015
  • Metastable phase characteristics of beta Ti alloys were investigated to consider the relationship of the microstructure and diffraction pattern in TEM. TEM analysis showed that the microstructure was mottled as a modulated structure, and the diffraction pattern was composed of spot streaks between the main spots of a stable beta phase with a specific lattice relationship. The modulated structure may be induced by short distance slip or atom movement during a very short interval of solution treated and quenched (STQ) materials. The athermal ${\omega}$ phase, which could be precipitated at low temperature aging, is also analysed by the metastable phase. The metastable phases including athermal ${\omega}$ phase had a common characteristic of hardened and brittle behavior because the dislocation slip was restricted by a super lattice effect due to short distance atom movement at the metastable state.

Sn Effects on Microstructure and Mechanical Properties of Ultrafine Ti-Fe-Sn Alloys (Sn 첨가에 따른 극미세 Ti-Fe-Sn 합금의 미세조직 및 기계적 성질 변화)

  • Han, Jun-Hee;Song, Gi-An;Pi, Dong-Hyouk;Bang, Chang-Wook;Kim, Ki-Buem
    • Journal of Korea Foundry Society
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    • v.28 no.2
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    • pp.69-73
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    • 2008
  • In the present study, microstructural evolution and mechanical properties of Ti-Fe-Sn ultrafine eutectic alloys have been investigated. Ultrafine eutectic microstructure consisting of a mixture of ${\beta}$-Ti solid solution and TiFe intermetallic compound homogeneously formed in $(Ti_{70.5}Fe_{29.5})_{100-x}Sn_x$ alloys with x = 0, 1 and 3. Addition of Sn is effective to modify the eutectic colony into the spherical shape with decreasing the lamellar spacing and colony size. This results in enhancing the macroscopic plasticity up to 3.1% of the Ti-Fe-Sn ultrafine eutectic alloys.

Advanced Powder Processing Techniques of Ti Alloy Powders for Medical and Aerospace Applications

  • Miura, Hideshi
    • Journal of Powder Materials
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    • v.20 no.5
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    • pp.323-331
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    • 2013
  • In this paper, two kinds of advanced powder processing techniques Metal Injection Molding (MIM) and Direct Laser Forming (DLF) are introduced to fabricate complex shaped Ti alloy parts which are widely used for medical and aerospace applications. The MIM process is used to strengthen Ti-6Al-4V alloy compacts by addition of fine Mo, Fe or Cr powders. Enhanced tensile strength of 1030 MPa with 15.1% elongation was obtained by an addition of 4 mass%Cr because of the microstructural modification and also the solution strengthening in beta phase. However, their fatigue strength was lower compared to wrought materials, but was improved by HIP. Subsequently, the effect of feeding layer height (FLH) on the characteristics of the DLF compacts was investigated. In the case of 100 ${\mu}m$ FLH, surface roughness was improved and nearly full density (99.8%) was obtained. Also, tensile strength of 1080 MPa was obtained, which is higher than the ASTM value.

Effect of Fe Content on Mechanical and Electrochemical Properties of Ti-Mo-Fe Alloys (Ti-Mo-Fe 합금의 Fe 함량에 따른 기계적 특성과 전기화학적 특성 비교·분석)

  • Ji-Won Kim;Jeong-Yeon Park;Min Gang;Ji-Hwan Park;Dong-Geun Lee
    • Journal of the Korean Society for Heat Treatment
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    • v.36 no.3
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    • pp.145-152
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    • 2023
  • β titanium alloys containing β stabilizing elements such as V, Nb, Ta, Mo and Fe are widely used etc, due to their excellent specific strength, corrosion resistance, fatigue strength and easy formability. New metastable β titanium alloys are developed containing low-cost elements (Mo and Fe) in this study. Fe element is a strong β-stabilizer which can affect the mechanical and electrochemical properties of Ti-5Mo-xFe (x = 1, 4 wt%) alloys. These properties were analyzed in connection with microstructure and phase distribution. Ti-5Mo-4Fe alloy showed higher compression yield stress and maximum stress than Ti-5Mo-1Fe alloy due to solid-solution hardening and grain refinement hardening effect. As Fe element increased, Fe oxide formation and reduction of ${\bar{Bo}}$ (bond order) value affect the decrease of corrosion resistance. Ti-5Mo-xFe alloys were more excellent than Ti-6Al-4V ELI alloy.

Investigation of High Temperature Deformation Behavior in Compression and Torsion of Ti-6Al-4V Alloy (Ti-6Al-4V합금의 비틀림 및 압축변형에 따른 고온변형거동 고찰)

  • Yeom, J.T.;Jung, E.J.;Kim, J.H.;Hong, J.K.;Park, N.K.;Lee, C.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.435-438
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    • 2008
  • High temperature deformation of Ti-6Al-4V alloy with a lamellar colony microstructure was investigated by hot compression and torsion tests. The torsion and compression tests were carried out under a wide range of temperatures and strain rates with true strain up to 2 and 0.7, respectively. The processing maps were generated on the basis of compression and torsion test data and using the principles of dynamic materials modeling (DMM). The shapes of the strain-stress curves in alpha-beta region and processing maps obtained on the two different tests have been compared with a view to evaluate the effect of the microstructure evolution on the flow softening behavior of Ti-6Al-4V alloy with a lamellar colony microstructure.

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Effect of Fe on the High Temperature Oxidation of Ti-Al-Fe Alloys (Ti-Al-Fe계 합금의 고온산화거동에 미치는 Fe의 영향)

  • Yoon, Jang-Won;Hyun, Yong-Taek;Kim, Jeoung-Han;Yeom, Jong-Taek;Yoon, Seog-Young
    • Korean Journal of Materials Research
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    • v.21 no.7
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    • pp.357-363
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    • 2011
  • In this paper, high temperature oxidation behavior of newly developed alloys, Ti-6Al-4Fe and Ti-6Al-1Fe, is examined. To understand the effect of Fe on the air oxidation behavior of the Ti-Al-Fe alloy system, thermal oxidation tests are carried out at $700^{\circ}C$ and $800^{\circ}C$ for 96 hours. Ti-6Al-4V alloy is also prepared and tested under the same conditions for comparison with the developed alloys. The oxidation resistance of the Ti-Al-Fe alloy system is superior to that of Ti-6Al-4V alloy. Ti-6Al-4V shows the worst oxidation resistance for all test conditions. This is not a result of the addition of Fe, but rather it is due to the elimination of V, which has deleterious effects on high temperature oxidation. The oxidation of the Ti-Al-Fe alloy system follows the parabolic rate law. At $700^{\circ}C$, Fe addition does not have a noticeable influence on the amount of weight gain of all specimens. However, at $800^{\circ}C$, Ti-6Al-4Fe alloy shows remarkable degradation compared to Ti-6Al-1Fe and Ti-6Al. It is discovered that the formation of $Al_2O_3$, a diffusion resistance layer, is remarkably hindered by a relative decrease of the ${\alpha}$ volume fraction. This is because Fe addition increases the volume fraction of ${\beta}$ phase within the Ti-6Al-xFe alloy system. Activities of Al, Ti, and Fe with respect to the formation of oxide layers are calculated and analyzed to explore the oxidation mechanism.

Biocompatibility of Ti-8Ta-3Nb alloy with fetal rat calvarial cells (백서 태자 두개관세포에서 Ti-8Ta-3Nb 합금의 생체적합성)

  • Cho, In-Goo;Cui, De-Zhe;Kim, Young-Joon;Lee, Kyung-Ku;Lee, Doh-Jae
    • Journal of Periodontal and Implant Science
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    • v.36 no.4
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    • pp.849-861
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    • 2006
  • 타이타늄은 기계적 특성이 우수하고 생체적합성이 뛰어나 의료용 장비의 주 재료로 사용되고 있으며 타이타늄 보다 기계적 특성이 더 우수한 타이타늄 합금들(주로 Ti-6Al-4V와 Ti-6Al-7Nb 합금)도 개발되어 치과와 의료용 임플란트로 사용되고 있다. 그러나 타이타늄 합금 성분들 중 알루미늄 (aluminum)과 바나디움(vanadium)은 인체에 노출되면 세포손상과 신경계에 문제를 일으킬 수 있다. 따라서 인체에 독성이 없으면서 기계적 성질과 생체적합성이 우수한 타이타늄 합금의 개발이 필요하다. 최근 인체에 독성이 없는 성분들이 함유된 새로운 ${\beta}$ - 형태의 타이타늄 합금들이 개발되고 있는데, ${\beta}$ - 타이타늄 합금은 그 기계적 성질이 기존의 ${\alpha}+{\beta}$ 타이타늄 합금에 비해 우수하다고 알려져 있다. 최근 새로운 ${\beta}$ - 타이타늄 합금이 전남대학교 부설 타이타늄 연구소에서 개발되었다. 이 연구는 새로 개발된 ${\beta}$ - 타이타늄 합금의 생채 적합성을 세포 증식도, 알카리 인산 분해 효소 활성과 유전자 증폭을 통해 알아보고자 하였다. 그 결과는 다음과 같다; 1. Titanium-6aluminum-4vanadium (Ti-6Al-4V) 합금 표면애서의 세포 증식율은 Titanium-Titanium8Tantalum-3Niobium (Ti-8Ta-3Nb) 합금과 순수 타이타늄 표면에 비해 유의하게 낮았다(p<0.00l). Ti-8Ta-3Nb 합금 표면에서의 증식도는 순수 타이타늄 표면과 유사하였다. 2. Ti-8Ta-3Nb 합금과 순수 타이타늄에서 배양된 세포이 알카리 인산 분해 효소의 활성도는 Ti-6Al-4V 합금에서의 것보다 유의하게 높았다 (p<0.001). 3. 유전자 증폭 분석 결과, Ti-8Ta-3Nb 합금과 순수 타이타늄에서 collagen type I과 bone sialoprotein mRNA 가 유사한 수준으로 발현되었다. 이상의 결과는 생체 적합성 측면에서 Ti-8Ta-3Nb 합금과 순수 타이타늄의 차이가 없음을 보여주며 따라서 Ti-8Ta-3Nb 합금이 의학 및 치의학 영역에서 새로운 임프란트 재료로 사용될 수 있음을 의미한다.