• 제목/요약/키워드: Fe-Cr-Mo

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The Effect of Elastic Anisotropy on the Shape of a Liquid Precipitate in a Wear-Resistant Fe-Base Alloy(Fe-5Cr- lMo-2Cu-0.5P-3C) (내마모 철계 소결합금(Fe-5Cr-lMo-2Cu-0.5P-3C)에서 정합변형이 액상석출물의 모양에 미치는 영향)

  • 신형상
    • Journal of Powder Materials
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    • v.1 no.1
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    • pp.60-65
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    • 1994
  • When a commercial prealloyed Fe-powder(Fe-5Cr-lMo-2Cu-0.5P-3C) is liquid phase sintered at 116$0^{\circ}C$, liquid precipitates with various shapes form within solid grains during the initial stage of sintering. The shape of a liquid precipitate changes pith the increment of their size from sphere(with radius<0.3$\mu\textrm{m}$), a transient polyhedron with more than 7 faces(1~2 $\mu\textrm{m}$), cuboid(3~5 $\mu\textrm{m}$), and finally to sphere(>5 $\mu\textrm{m}$). The shapes of liquid precipitates closely resemble the growth shapes predicted on the basis of solid-liquid interfacial energy and the coherency strain energy with anisotropic elastic constants in the diffusion zone around the precipitates.

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Fabrication and Magnetic Properties of A New Fe-based Amorphous Compound Powder Cores

  • Xiangyue, Wang;Feng, Guo;Caowei, Lu;Zhichao, Lu;Deren, Li;Shaoxiong, Zhou
    • Journal of Magnetics
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    • v.16 no.3
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    • pp.318-321
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    • 2011
  • A new Fe-based amorphous compound powder was prepared from Fe-Si-B amorphous powder by crushing amorphous ribbons as the first magnetic component and Fe-Cr-Mo metallic glassy powder by water atomization as the second magnetic component. Subsequently by adding organic and inorganic binders to the compound powder and cold pressing, the new Fe-based amorphous compound powder cores were fabricated. This new Fe-based amorphous compound powder cores combine the superior DC-Bias properties and the excellent core loss. The core loss of 500 kW/$m^3$ at $B_m$ = 0.1T and f = 100 kHz was obtained When the mass ratio of FeSiB/FeCrMo equals 3:2, and meanwhile the DC-bias properties of the new Fe-based amorphous compound powder cores just decreased by 10% compared with that of the FeSiB powder cores. In addition, with the increasing of the content of the FeCrMo metallic glassy powder, the core loss tends to decrease.

Corrosion of Fe-9%Cr-1%Mo Steel at 600 and 700℃ in N2/(0.5, 2.5)%H2S-mixed Gas

  • Lee, Dong Bok;Abro, Muhammad Ali;Yadav, Poonam;Bak, Sang Hwan;Shi, Yuke;Kim, Min Jung
    • Journal of the Korean institute of surface engineering
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    • v.49 no.2
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    • pp.147-151
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    • 2016
  • The T91 steel (Fe-9%Cr-1%Mo) was corroded at 600 and $700^{\circ}C$ for 5 - 70 h in the $N_2$/(0.5, 2.5)%$H_2$Smixed gas at one atm. It was corroded fast, forming the outer FeS layer and the inner (FeS, $FeCr_2O_4$)-mixed layer. The formation of the outer FeS layer facilitated the oxidation of Cr to $FeCr_2O_4$ in the inner layer. Since the nonprotective FeS scale was present over the whole scale, T91 steel displayed poor corrosion resistance.

Heavy Metal Pollution in Soil and Vegetation near the Closed Daeseong Coal Mine in Keumsan, Chungnam (충남 금산 폐탄광지역의 토양 및 식물체내 중금속 오염)

  • 민일식;송석환;김명희
    • Journal of Korea Soil Environment Society
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    • v.3 no.2
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    • pp.41-51
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    • 1998
  • The research was conducted to measure the heavy metal pollution of soils and vegetations adjacent to the closed Daeseong coal mine in Keumsan, Chungnam. The studied area was divided into two sites ; the coal-bearing polluted and the non-polluted without coal. The samples of the weathered soils and vegetations(Miscnthus sinenis(MS) and Pinus rigida(PR)) were collected from both area. Cr, Mo, Ni, and Fe concentrations were high in the polluted soils, whereas Co, Sc, and Zn concentrations were high in the non-polluted soils. In the vegetations, Co, Cr, Sc, and Fe concentrations in the roots of MS and PR growing on the polluted sites were higher than the above-ground. However, on the non-polluted sites, Mo and Ni concentrations had an opposite trend. In the above-ground parts, high heavy metal concentrations (except Cr) were shown in MS of the non-polluted sites, whereas in the roots, heavy metal concentrations (except Zn) were high in the polluted sites. In the average heavy metal concentrations of two plants, most elements (except Zn) were lower in the plants than the soils. Comparing with vegetations and adjacent forest soils, heavy metal concentrations of the MS were similar to those of soil concentrations relative to the PR, suggesting that absorptions of the elements were higher in the MS than the PR.

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Dietary Intakes, Serum Concentrations, and Urinary Excretions of Fe, Zn, Cu, Mn, Se, Mo, and Cr of Korean Young Adult Women (일부 젊은 성인여자의 Fe, Zn, Cu, Mn, Se, Mo 및 Cr의 식사섭취, 혈청농도 및 소변배설)

  • Kim, Kyune-Hee;Lim, Hyeon-Sook
    • Journal of Nutrition and Health
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    • v.39 no.8
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    • pp.762-772
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    • 2006
  • This study was conducted to investigate dietary intakes, serum concentrations, and urinary excretions of iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), selenium (Se), molybdenum (Mo), and chromium (Cr) of Korean young adult women. A total of 19 apparently healthy young adult women aged in their twenties or thirties participated voluntarily. One-tenth of all foods they consumed for 3 consecutive days were collected, all urine excreted for the same 3 days was gathered, and fasting venous blood was withdrawn for the trace mineral analyses. Of the food, blood, and urine samples, the contents of Zn, Cu, Mn, Se, Mo, and Cr were analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS) and that of Fe by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) after wet digestion. The intake of Fe, $6.94{\pm}2.18mg$, did not meet the estimated average requirement (EAR) for Korean women aged 20-29 years old. On the contrary, the intakes of Zn ($9.35{\pm}4.95mg$), Cu ($1.18{\pm}0.26mg$), and Mn ($3.69{\pm}0.69mg$) were sufficient for each respective EAR. However, some of the subjects did not take the EAR for Zn. The Se intake, $41.93{\pm}9.28{\mu}g$, however, was almost similar to the EAR for Se. Although there are no references for Mo and Cr, the intakes of these minerals ($134.0{\pm}49.1\;and\;136.5{\pm}147.9{\mu}g$, respectively) seemed to be excessively sufficient. Serum Fe concentration, $88.7{\pm}36.8{\mu}g/dL$, seemed to be a little bit lower than its reference median but within its normal range. Approximately one-fourth of the subjects were in anemic determined by Hb and Hct and below the deficiency serum level of Fe, $60{\mu}g/dL$. In addition, serum Se concentration, $3.73{\pm}0.60{\mu}g/dL$, was also below its reference median and normal range. However, serum concentrations of Zn ($99.6{\pm}30.6{\mu}g/dL$) and Mo ($0.25{\pm}0.10{\mu}g/dL$) were fairly good compared to each reference median. The status of Cu could be determined as good although its serum concentration ($91.6{\pm}14.6{\mu}g/dL$) was slightly below its reference median. Since there are no decisive reference values, it was not easy to evaluate serum concentrations of Mn ($0.93{\pm}0.85{\mu}g/dL$) and Cr ($8.60{\pm}7.25{\mu}g/dL$). But Mn and Cr status seemed to be adequate. Urinary Fe excretion, $4.48{\pm}1.98{\mu}g/dL$, was pretty much lower than its reference and that of Se, $2.45{\pm}1.17{\mu}g/dL$, was also lower than its average. On the other hand, those of Zn ($42.95{\pm}20.47{\mu}g/dL$) and Cu ($5.68{\pm}1.50{\mu}g/dL$) were flirty good. In case of Mn, urinary excretion, $0.31{\pm}0.09{\mu}g/dL$, was much greater than its reference. Urinary excretions of Mo ($7.48{\pm}2.95{\mu}g/dL$) and Cr ($1.37{\pm}0.41{\mu}g/dL$) were very higher compared to each reference. The results of this study revealed that Korean young adult women were considerably poor in Fe status, a bit inadequate in Se status, partly inadequate in Zn status, and flirty good in Cu, Mn, Mo and Cr status. However, there was a problem of excessive intakes of Mo and Cr. It, therefore, should be concerned to increase the intakes of Fe, Se and Zn but to decrease Mo and Cr consumption for young adult women.

Austenite Stability and Mechanical Properties of Nanocrystalline FeNiCrMoMnSiC Alloy Fabricated by Spark Plasma Sintering (방전플라즈마소결로 제조된 나노결정 FeNiCrMoMnSiC 합금의 오스테나이트 안정성과 기계적 특성)

  • Park, Jungbin;Jeon, Junhyub;Seo, Namhyuk;Kim, Gwanghun;Son, Seung Bae;Lee, Seok-Jae
    • Journal of Powder Materials
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    • v.28 no.4
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    • pp.336-341
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    • 2021
  • In this study, a nanocrystalline FeNiCrMoMnSiC alloy was fabricated, and its austenite stability, microstructure, and mechanical properties were investigated. A sintered FeNiCrMoMnSiC alloy sample with nanosized crystal was obtained by high-energy ball milling and spark plasma sintering. The sintering behavior was investigated by measuring the displacement according to the temperature of the sintered body. Through microstructural analysis, it was confirmed that a compact sintered body with few pores was produced, and cementite was formed. The stability of the austenite phase in the sintered samples was evaluated by X-ray diffraction analysis and electron backscatter diffraction. Results revealed a measured value of 51.6% and that the alloy had seven times more austenite stability than AISI 4340 wrought steel. The hardness of the sintered alloy was 60.4 HRC, which was up to 2.4 times higher than that of wrought steel.

Corrosion and Mechanical characteristics for 9Cr-1MoVNb Steel under SO2 gas environment (SO2 가스 환경 하에서 9Cr 템퍼드-마르텐사이트강의 부식 및 기계적 특성)

  • Jeong, Gwang-Hu;Kim, Seong-Jong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.109-109
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    • 2018
  • Cr-Mo 합금강은 고온 환경 하에서 높은 크리이프 강도와 우수한 내식성 때문에 발전설비, 석유 화학, 그리고 해양산업과 같은 여러 산업분야에서 널리 사용되고 있다. 특히, Cr-Mo 강의 내식성은 합금 내 Cr 함량에 크게 의존한다. 이는 고온에서 Cr과 O가 화학적 반응을 일으킴에 따라 보호성의 Cr 산화스케일을 형성하기 때문이다. 그러나 화석연료를 사용하는 발전설비의 경우, $SO_2$가 포함된 강한 부식성의 연소 가스가 배출되며, 이에 노출된 금속의 표면에서는 산화와 황화가 동시에 발생한다. 황화스케일은 산화스케일에 비해 매우 빠르게 성장하며, 그 특성이 매우 취약하기 때문에 황화 환경에서 금속의 내식성 및 기계적 물성치는 보다 크게 저하된다. 따라서 본 연구에서는 화력 발전소의 증기발생용 튜브 재료인 9Cr-1MoVNb 강을 선정하였으며, $SO_2$ 가스 환경 하에서의 부식 및 기계적 물성치 저하 특성을 평가하고자 하였다. 본 연구에서 사용된 9Cr-1MoVNb강의 화학 성분 조성은 0.1 C, 0.38 Si, 0.46 Mn, 0.25 Ni, 8.38 Cr, 0.93 Mo, 0.18 V, 0.09 Nb, 그리고 나머지는 Fe이다. 부식시험은 가공된 미소시험편과 인장시험편을 전기열처리로에 장입한 후, $650^{\circ}C$에서 $N_2+O_2+O_2+SO_2$ 조성의 가스를 분당 50 CC로 흘려주었다. 제작된 시험편에 대한 부식거동은 무게 증가량, optical microscope, scanning electron microsope, 그리고 energy dispersive x-ray spectrum을 통해 평가하였다. 그리고 기계적 물성치 평가를 위한 인장시험은 분당 2mm 변위제어를 통해 실시하였다. 그 결과, 9Cr-1MoVNb 강은 $SO_2$ 가스 환경 하에서 비 보호적인 Fe-풍부상의 산화 스케일층이 두껍게 형성됨에 따라 열악한 내식성을 나타냈다. 그에 따라 기계적 물성치는 저하되는 경향을 나타내었다.

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