• Title, Summary, Keyword: solutionized alloy

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Effect of Trace Amount of Ca on Corrosion Resistance of Solutionized Mg-4%Zn Alloy (용체화처리된 Mg-4%Zn 합금의 부식 저항성에 미치는 미량 Ca 첨가의 영향)

  • Jun, Joong-Hwan;Hwang, In-Je
    • Journal of the Korean Society for Heat Treatment
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    • v.29 no.4
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    • pp.168-175
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    • 2016
  • Influence of trace amount of Ca addition on the corrosion resistance was comparatively investigated in solutionized Mg-4%Zn and Mg-4%Zn-0.1%Ca alloys. In as-cast state, the alloys were characterized by primary ${\alpha}-(Mg)$ dendrite with MgZn intermetallic compound particles. After solution-treatment, both alloys consisted of single ${\alpha}-(Mg)$ phase by dissolution of the compound particles into the matrix. It was found from the immersion and electrochemical corrosion tests that the Mg-4%Zn alloy had better corrosion resistance than the Mg-4%Zn-0.1%Ca alloy. Morphological and compositional analyses on the surface corrosion products indicate that the incorporation of Ca oxide with low PBR value into the surface corrosion products would be responsible for the decreased corrosion resistance of the Ca-containing alloy.

A Study on the Development of Al Alloy for the Vehicle Connecting Rod Using Hot Forging (열간단조공법을 이용한 컨로드용 Al 합금의 개발에 관한 연구)

  • Kim, S.H.;Hwang, T.M.
    • Journal of the Korea Society For Power System Engineering
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    • v.12 no.1
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    • pp.66-71
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    • 2008
  • Alumium alloys hot forging process are gaining increased acceptance in the automotive and electronic industries and hot forging is one of the most efficient manufacturing method for mass product parts. It has been investigated the microstructures and mechanical properties of Al-11.7Si-0.5Mg (KNT40-T6)alloy fabricated by hot forging process for development of connecting rod in this study. The microstructure of hot forged specimen was composed of eutectic structure of alumimum solid solution and $Mg_2Si$ precipitates. The tensile strength of solutionized Al-11.7Si-0.5Mg alloy was 217MPa. This alloy showed a good corrosion resistance using electrochemical polarization test.

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Dependence of Damping Capacity on ${\beta}$ Phase Precipitation in Mg Alloy (Mg 합금에서 진동감쇠능의 ${\beta}$상 석출 의존성)

  • Jun, Joong-Hwan
    • Journal of the Korean Society for Heat Treatment
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    • v.20 no.6
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    • pp.306-310
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    • 2007
  • Changes in microstructure and damping capacity with aging time for solutionized Mg-Al alloy have been investigated. Discontinuous ${\beta}\;(Mg_{17}Al_{12})$ precipitates form along the primary grain boundaries, the amount of which increases as the aging time increases. The hardness of the matrix with respect to aging time shows a typical "S" shape, indicating a generation of fine continuous precipitates in the matrix during the aging. The peak level of damping capacity is obtained after 1 hour of aging, over which the damping capacity becomes deteriorated continuously. The formation of optimum density of continuous ${\beta}$ precipitates with fine morphology which would act as pinning points for dislocation lines, might be responsible for the improvement of damping capacity.

Plastic Deformation Behavior of Ti-51.5at.%Ni Shape Memory Alloy Single Crystals (Ti-51.5at.%Ni 형상기억합금 단결정의 소성변형 거동)

  • Jun, Joong-Hwan;Sehitoglu, Huseyin
    • Journal of the Korean Society for Heat Treatment
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    • v.15 no.1
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    • pp.9-15
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    • 2002
  • Deformation behavior of nickel-rich Ti-51.5at.%Ni single crystals was investigated over a wide range of temperatures(77 to 440K) and strain levels(up to 9%) in compression. These alloys combined superior strength with wide range of pseudoelasticity temperature interval(~200K). The slip deformation in [001] orientation did not occur due to the prevailing slip system, and consequently, exhibited pseudoelastic deformation at temperatures ranging from 77 to 283K and 273 to 440K for the solutionized and over-aged cases, respectively. The critical transformation stress levels were in the range of 800 to 1800MPa for the solutionized case, and 200 to 1000MPa for the over-aged case depending on the temperature and specimen orientation. These stress levels are considerably higher compared to these class of alloys having lower Ni contents. The maximum transformation strains, measured from incremental straining experiments in compression, were lower compared to the phenomenological theory with Type II twinning. A compound twinning model depending on the successive austenite(B2) to intermediate phase(R) to martensite(B19') transformation predicts lower transformation strains compared to the Type II twinning case.

Mechanical Alloying Behavior and Microstructures of Extrudate in Al-Ti-(Si) Base Alloys (A1-Ti-(Si)계 합금의 기계적 합금화 및 성형체의 미세조직)

  • 최철진
    • Journal of Korean Powder Metallurgy Institute
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    • v.2 no.2
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    • pp.165-170
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    • 1995
  • Alloying behavior of nanocrystalline Al-Ti-(Si) composite powders via mechanical alloying (MA) has been investigated, and the effect of Si on the microstructural changes during MA was discussed. The microstructures of both MA powders and extruded compacts were examined. In Al-Ti system, the solid solutionized nanocrystalline powders could be obtained by MA. On the contrary, fine Si particles were embedded as an elemental state in the matrix of Al-Ti-Si system because of the brittleness and the negligible solid solubility of Si in Al. After hot extrusion, $Al3Ti$ phase was finely precipitated in Al-10fSTi alloy, and Si particles were dissolved to form $(Al, Si)_3Ti$ phase in Al-10%Ti-2%Si alloy.

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A Study on the Shape Memory Characteristic Behaviors of Ti-42.5at%Ni-10at.% Cu Alloys (Ti-42.5at.%Ni-10at.%Cu합금의 형상기억특성에 관한 연구)

  • Woo, Heung-Sik;Park, Yong-Gyu
    • Journal of the Korean Society of Safety
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    • v.24 no.1
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    • pp.26-30
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    • 2009
  • Shape memory recoverable stress and strain of Ti-42.5at%Ni-10at%Cu alloys were measured by means of constant temperature tensile tests. The alloys' transformation behavior is B2 - B19 by DSC result. The strain by tensile stress were perfectly recovered by heating at any testing conditions but shape memory recoverable stress increased to 66MPa and then slightly decreased. Transformation temperatures from thermal cycling under constant uniaxial applied tensile loads linearly increased by increasing tensile load and their thermal hysteresis are about 110K and their maximum recoverable strain is 6.5% at 100MPa condition.

A Study on the Shape Memory Characteristic Behaviors of Ti-42.5at.%Ni-2.0at.%Cu Alloys in Tension and Compression Condition (Ti-42.5at.%Ni-2.0at.%Cu합금의 인장 및 압축에 따른 형상기억특성에 관한 연구)

  • Woo, Heung-Sik;Cho, Jae-Whan;Park, Yong-Gyu
    • Journal of the Korean Society of Safety
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    • v.24 no.5
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    • pp.1-5
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    • 2009
  • NiTiCu alloys can produce a large force per unit volume and operate with a simple mechanism. For this reasons, it has been widely studied for application as a micro actuator. So in this study, one-way and two way shape memory effects of Ti-42.5at%Ni-2.0at%Cu alloys are studied. In the case of one-way shape memory effects, shape memory recoverable stress and strain of this alloys were measured by means of tension and compression tests under constant temperature. The strains by tension and compression stress were perfectly recovered by heating at any testing conditions also shape memory recoverable stress increased to 116 MPa in tension tests and to 260 MPa in compression tests. In the case of two-way shape memory effects, transformation temperatures from thermal cycling under constant uniaxial applied tension and compression loads linearly increased by increasing external loads and their maximum recoverable strain is 3.8% at 100MPa tensile condition and 2.2% at 125 MPa compression condition.

Corrosion Behavior of Hard Coated Ti-Zr-N Film on the Tool Steels

  • Eun, Sang-Won;Choe, Han-Cheol
    • Corrosion Science and Technology
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    • v.9 no.6
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    • pp.289-293
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    • 2010
  • To investigate the corrosion behavior of tools steel surface in various coating film, the surface of hard coated Ti-Zr-N film on the tool steel by using magnetron-sputtering methods was researched using various experimental methods. STD 61 steels were manufactured by using vacuum furnace and solutionized for 1hr at $1050^{\circ}C$. Steel surface was coated with Ti-Zr-N film at $150^{\circ}C$ and 100W for 1h by using DC-sputtering equipment. Surface characteristics of Ti-Zr-N film coated specimens were investigated by OM, XRD, FE-SEM and nano-scratch tester. And corrosion behaviors of the coated specimen were investigated by polarization test and electrochemical impedance spectroscopy(EG&G Co, PARSTAT 2273. USA). It was found that Ti-Zr-N film coated sample had a thick coated layer and showed a good wear resistance and corrosion resistance of surface compared with ZrN and TiN coated sample. The corrosion resistance and mechanical property of Ti-Zr-N film coated STD 61 alloy increased as sputtering time increased.

Effect of Crystallization Treatment on the Magnetic Properties of Amorphous Strips Based on Co-Fe-Ni-B-Si-Cr Containing Nitrogen

  • Cho H.J.;Kwon H.T.;Ryu H.H.;Sohn K.Y.;You B.S.;Park W.W.
    • Journal of Korean Powder Metallurgy Institute
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    • v.13 no.4
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    • pp.285-289
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    • 2006
  • Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of $300^{\circ}C{\sim}540^{\circ}C$ for up to 30 minutes in an inert gas $(N_2)$ atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at $540^{\circ}C$ showed that the grain size of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.

The Corrosion Behavior Study by AC Impedance Method for the Aging Heat Treated Nimonic 80A Superalloy (교류임피던스법에 의한 Nimonic 80A 초내열합금 시효열처리재의 부식거동 고찰)

  • 백신영
    • Journal of the Korean Society of Marine Engineering
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    • v.23 no.6
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    • pp.761-769
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    • 1999
  • In this paper the effect of aging heat treatment to the Corrosion behavior for the Nimonic 80A superalloy was studied by AC Impedance methods. Tested solution was 3.5% with tempera-ture $25^{\circ}C$ Electro-chemical corrosion test were carried out for the Nimonic 80A super-alloy which solution heat treated at $1080^{\circ}C$ for 8 hours followed by aging heat treated at $650^{\circ}C,\;700^{\circ}C,\;750^{\circ}C\;800^{\circ}C$ and $850^{\circ}C$ with 16hours under vacuum environment. The obtained results were as follows; 1. Base metal and solution-treated materials were exhibited similar corrosion tendency as Ran-dle equivalent cell. The value of passive film resistance was 579 ohms for the base metal and 124,770 ohms for the solutionized metal such a difference was arose by the ${{\gamma}_^'}$ precipitate on the metal surface during heat treatment. 2. The measure value of $R_p$ for heat-treated at $650^{\circ}C,\;700^{\circ}C,\;800^{\circ}C$and $850^{\circ}C$ were 97,943, 93, 111, 26,961, 15,798 and 11,780ohm respectively. Which indicated that the passive film resistance Rp was reduced as aging temperature increased due to the growth of grain size and sensitization at the grain boundary. 3. The similar tendency was exhibited for corrosion behavior of the electro-chemical corrosion polarization method and AC impedance method and confirmed that AC impedance method was useful tool for corrosion research.

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