• Title/Summary/Keyword: 순 티타늄

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Analysis of castability in c.p.Ti according to casting conditions (주조조건에 따른 순티타늄의 주조성 분석)

  • Hwang, Seong-Sig;Kwon, Seog-Suk
    • Journal of Technologic Dentistry
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    • v.29 no.1
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    • pp.133-138
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    • 2007
  • In this study, the castability and of commercially pure titanium(c.p.Ti) grade according to the casting condition which are the vacuum condition in casting machine and mold temperature of investment, was investigated. Argon-arc melt/centrifugal casting machine was used for casting the specimens. The microstructure and mechanical properties were evaluated by using optical microscope. The results were as follows; 1. It could make a sure that there's relatively not much defect of casting body of c.p.Ti according to the deference of air pressure. 2. It could make sure that it formed porosity on the surface inside of the casting body of c.p.Ti according to deferent temperature. and on excellent castability was below $200^{\circ}C$ 3. As the mold temperature of investment was increased, the lamellar structure of phase and coarse grains were shown, especially under 42MPa.

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Electrochemical Behavior and Morphology of Anodic Titanium Oxide Films (양극산화에 의한 티타늄 산화피막의 전기화학적 거동과 형상)

  • Byeon K.J.;Kim C.S.;Zhu Xiaolong;Kim K.H.
    • Journal of Biomedical Engineering Research
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    • v.21 no.3
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    • pp.273-277
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    • 2000
  • The galvanostatic anodization of commercially Pure titanium plate (c.p.Ti, grade 2) was investigated in various concentrations of aqueous $H_3PO_4$ from 0.05M to 0.7M. The surfaces of anodic oxide films, formed by the current density in the range between 0.3 and $l.0 A/dm^2$. were analyzed by SEM and XRD. The voltage-time (V-T) curves displayed an initial linear part and a subsequent parabolic part, and the initial slopes increased with an increase in the current density in 0.05M $H_3PO_4$. As the concentration of the electrolyte increased, the V-T corves exhibit no change but the final voltage decreased. The anodic oxide film of titanium developed from fine grains to snowflake-like grains in a layered structure with an increase in the concentration of the electrolyte and current density. Sparking at the interface of the oxide/electrolyte accompanied the local deposition and dissolution of the oxide film through discharging. The crystallinity of the anodic oxide film increased with the anodizing voltage and decreased with an increase in the concentration of the electrolyte.

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Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (I) - Effect of Type and Flow Rate of Shielding Gases on Weldability - (티타늄 판재의 파이버 레이저 용접시 공정변수에 따른 용접특성 (I) - 실드가스 종류 및 유량에 따른 영향 -)

  • Kim, Jong Do;Kim, Ji Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.12
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    • pp.1047-1053
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    • 2016
  • In this study, welding of pure titanium was carried out by using a continuous wave fiber laser with a maximum output of 6.3 kW. Because brittle regions form easily in titanium as a result of oxidation or nitriding, the weld must be protected from the atmosphere by using an appropriate shielding gas. Experiments were performed by changing the type and the flow rate of shielding gases to obtain the optimal shielding condition, and the weldability was then evaluated. The degree of oxidation and nitriding was distinguished by observing the color of beads, and weld microstructure was observed by using an optical microscope and a scanning electron microscope. The mechanical properties of the weld were examined by measuring hardness. When the weld was oxidized or nitrified, the bead color was gray or yellow, and the oxygen or nitrogen content in the bead surface and overall weld tended to be high, as a result of which the hardness of the weld was thrice that of the base metal. A sound silvery white bead was obtained by using Ar as the shielding gas.

A Study of Weldability for Pure Titanium by Nd:YAG Laser(I) - Weld Properties with Shield Conditions - (순티타늄판의 Nd:YAG 레이저 용접성에 관한 연구(I) - 실드 조건에 따른 용접특성 -)

  • Kim, Jong-Do;Kwak, Myung-Sub;Kim, Chang-Soo
    • Journal of Welding and Joining
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    • v.27 no.5
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    • pp.55-61
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    • 2009
  • Pure titanium and its alloys have good formability, excellent corrosion resistance and high strength to weight ratios. Therefore, it has been using to heat exchangers, offshore plants, sports equipments, and etc. As broad as its application fields, it also increases welding locations. Conventional GTAW and GMAW are very popular welding methods of titanium, but it has a high heat input and wide HAZ. It has a possibility of inducing Stress Corrosion Cracking. So, laser welding method has been using to get reliable welds by reducing heat input. Weld beads change its color to silver, gold, brown, blue, and gray by shied conditions. And the closer to gray, the more oxidize, nitride and embrittlement. The most effective atom to embrittlement was nitrogen. And shield gas flow was not so effective over the constant flow rates. In this study, weld properties of the pure titanium were investigated by pulsed & CW Nd:YAG lasers and evaluated by various shield conditions. And It is observed that nitrogen is more effective to oxidation and embrittlement of titanium compared with oxygen by oxygen and nitrogen quantitative analysis.

A Study on Non-propagating Crack in Fatigue Behavior of Pure Titanium (공업용 순 티타늄의 피로거동에서 정류균열에 관한 연구)

  • Kim, Dong-Yeol;Kim, Jin-Hak;Kim, Min-Geon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4
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    • pp.1001-1006
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    • 2000
  • To verify the existing theory, non-propagating crack(NPC) does not exist in Ti which fulfills the good conditions for being of NPC, NPC detection in Ti was tried out. Also, the conception of fatigue limit in Ti and a main cause for NPC being were inquired. NPC was detected in both sharp notch root ( $\rho$=0.02mm) and micro pit (diameter = 0.25mm) which held fast to the end under stressing of fatigue limit. Therefore, the existing theory was identified as mistake. But, NPC can not be detected in smooth specimen. This fact would be due to the presumption that NPC is very small or crack does not initiate in smooth specimen. Anyway, the fatigue limit of Ti does not correspond to critical stress of crack initiation but correspond to critical stress of NPC growth. Measurement on the COD of NPC in Ti showed that the crack tip was closed even under the peak stress level at fatigue limit. But, after stress relieving annealing crack tip was opened. Consequently, compressive residual stress which is induced around the crack tip is considered to be the factor causing the NPC being.

Acoustical Anisotropy Evaluation of Pure Titanium plate Using Neural Network (신경회로망을 이용한 순 티타늄판재의 음향이방성 평가)

  • Park, Hee-Dong;Yun, In-Sik;Yi, Won
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.9
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    • pp.1103-1109
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    • 2011
  • This research quantitatively confirmed an acoustical anisotropy that exists in a pure titanium plate from the signal of ultrasonic flow detection and suggested a new way to evaluate the acoustical anisotropy by inputting acquired characteristic of ultrasound signal into the neutral network. Using the fact with the suggested method that the characteristic of ultrasound signal is shown differently depending on the pure titanium plate's rolling direction, the neural network was constructed by extracting the characteristic that can decide each direction of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ with waveform analysis program. As a result of inputting the characteristic of ultrasound signal acquired from a random rolling direction into the neural network that was built like this, it showed a pattern recognition rate higher than 95% on directions of $0^{\circ}$, $45^{\circ}$, $90^{\circ}$.

The Effects of Anodizing Process Parameters and Oxidation Temperature under Atmospheric Environment on Morphology of the Pure Titanium by Alternating Current Arc-anodizing (순티타늄의 교류 불꽃 양극산화층 미세조직에 미치는 양극산화공정변수 및 대기산화온도의 영향)

  • Yang, Hack-Hui;Park, Chong-Sung
    • Journal of the Korean institute of surface engineering
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    • v.41 no.1
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    • pp.16-22
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    • 2008
  • Anodizing to form oxide layers on the pure titanium was performed in the electrolyte containing 1.5M $H_2SO_4$, 0.2M $H_3PO_4$, and 2.5wt.% $CuSO_4$ using the ac-biased arc anodizing technique. Titanium oxide layers anodized with different applied voltages, voltage-elevating rates, and anodizing times were investigated. In addition, thermal oxidation test under an atmospheric environment for the arc-anodized specimens was carried out. The thickness of oxide layers were not affected by the voltage-elevating rates, but increased slightly with the increase of anodizing times. The thickness of oxide layers were increased with the increase of voltages, and increased remarkably in the condition of 200V. The size and number of the pore observed in the center of the porous cell were decreased with increase of applied voltage. From the result of thermal oxidation test, it revealed that oxide layer formed by arc anodizing more effective to prevent oxidation of pure titanium.

The Characteristics of Continuous Waveshape Control for the Suppression of Defects in the Fiber Laser Welding of Pure Titanium Sheet (II) - The Effect According to Control of Overlap Weld Length - (순 티타늄 박판의 파이버 레이저 용접시 결함 억제를 위한 연속의 출력 파형제어 특성(II) - 중첩부 길이변화에 따른 영향 -)

  • Kim, Jong-Do;Kim, Ji-Sung
    • Journal of Welding and Joining
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    • v.34 no.6
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    • pp.69-74
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    • 2016
  • Because the pure titanium has superior corrosion resistance and formability compared with different material, it is widely used as material of welded heat exchanger. When the welding of heat exchanger is carried out, certain area in which welding start and end are overlapped occurs. The humping of back bead is formed in the overlap area due to partial penetration. Thus in this study, the experiments were carried out by changing the length and wave shape of overlap area, and then the weldabiliay was evaluated through the observation of microstructure, the measurement of hardness and tensile-shear strength test in the overlap area. When overlap length was 9.8mm, humping bead was suppressed. The microstructure of overlap area coarsened and its hardness increased due to remelting. As a result of tensile-shear strength test in the overlap area according to applying the wave shape control, it was confirmed that the overlap area applied wave shape control had more excellent yield strength and ductility.

A Study on Plastic Deformation Characteristics and Formability for Pure Titanium Sheet (순 티타늄 판재의 변형 특성 및 성형성 평가)

  • In, J.H.;Jeong, K.C.;Lee, H.S.;Kim, J.H.;Kim, J.J.;Kim, Young Su
    • Transactions of Materials Processing
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    • v.27 no.5
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    • pp.301-313
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    • 2018
  • In this paper, tensile test was performed on pure titanium sheet (CP Ti sheet) with HCP structure in each direction to evaluate mechanical and surface properties and analyze microstructural changes during plastic deformation. We also evaluated forming limits of Ti direction in dome-type punch stretching test using a non-contact three-dimensional optical measurement system. As a result, it was revealed the pure titanium sheet has strong anisotropic property in yield stress, stress-strain curve and anisotropy coefficient according to direction. It was revealed that twinning occurred when the pure titanium sheet was plastic deformed, and tendency depends differently on direction and deformation mode. Moreover, this seems to affect the physical properties and deformation of the material. In addition, it was revealed the pure titanium sheet had different surface roughness changes in 0 degree direction and 90 degree direction due to large difference of anisotropy, and this affects the forming limit. It was revealed the forming limit of each direction obtained through the punch stretching test gave higher value in 90 degree direction compared with forming limit in 0 degree direction.

Characteristics of Brazing of Eyewear Frame Ti Alloy with Electric Resistance (전기저항을 이용한 안경테용 Ti 합금의 땜질 특성)

  • Park, Jeong-Sik;Lee, Jeong-Yeong
    • Journal of Korean Ophthalmic Optics Society
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    • v.12 no.4
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    • pp.15-18
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    • 2007
  • Titanum and its alloys have been used as the important materials of eyewear frame because of its light weight, mechanical strength and corrosion resistance. This study investigated the characteristics of P-Ti and ${\beta}$-Ti alloys in accordance with joining conditions by electric resistance brazing. Hardness of P-Ti and ${\beta}$-Ti has been reduced because of an increase of grain size by the growth of brazing time. Hardness reduction and reduction area by grain growth were largely appeared in P-Ti than ${\beta}$-Ti.

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