• 제목/요약/키워드: Cast Iron

검색결과 692건 처리시간 0.029초

흑심가단주철의 제 1 단 흑연화에 미치는 Se, $CaCO_3$ 및 CaO첨가의 영향 (The effects of Se, $CaCO_3$ and CaO addition on the 1st stage graphitization of malleable cast iron)

  • 이호종;나형용
    • 한국주조공학회지
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    • 제6권4호
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    • pp.269-276
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    • 1986
  • The effects of Se, $CaCO_3$ and CaO addition on the first stage graphization of malleable iron were evaluated. The results obtained in this work were as follows. 1. Many gas bubbles were found in the white cast iron under Se, $CaCO_3$ addition. 2. Nodular graphite were formed by annealing of the white cast iron with remained gas bubbles. 3. When specimens were annealed, bubbles provided the nucleation sites that were needed in graphite precipitation, so the nucleation rate of graphite was increased. 4. The remained gas bubbles and defects were more effective for the graphitization than metallic compounds.

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기지내 반응법에 의한 WC 복합재료의 제조에 관한 연구(1);주조접합된 주철/텅스텐 와이어의 계면반응층 생성기구와 조직특성 (A Study on the Manufacture of WC MMCs by In-situ Reaction Process(1);The Formation Mechanism of Interfacial Reaction Layer in Cast-bonded Cast iron/W wire and Its Structure)

  • 박흥일;김창업;허보영;이성렬;김창규
    • 한국주조공학회지
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    • 제15권3호
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    • pp.272-282
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    • 1995
  • Iron-based metal matrix composites have been recently investigated for the use of inexpensive abrasion resistance material. This paper carried out to investigate the in-situ reaction effects on the microstructural characteristics and the formation mechanism of tungsten carbides in a white cast iron matrix. The specimens of Fe-3.2%C-2.8%Si alloy cast-bonded with tungsten wire were cast in the metal mold and isothermally heat treated at $950^{\circ}C$ up to 48 hours. The typical microstructure of heat treated specimens showed the reaction layer of WC at the interface of tungsten wire and the carbon depletion zone between the WC layer and the matrix. During the formation of WC layer, if the carbon supply is insufficient due to the decarburization of matrix or the isolation of matrix by cast-bonded W wires, the reaction layer develops coarse hexagonal crystalline WC. From the microstructural investigation, it was found that the volume of WC layer and the carbon depletion zone increased linearly with the isothermal heat treating time. This results supported that the formation rate of WC in the white cast iron matrix is controlled by the interfacial reaction with a constant reaction rate.

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오스템퍼 회주철의 파괴강도 특성에 관한 연구 (A Study on Characteristics of Strength and Fracture of Austempered Graphite Cast Iron)

  • 이하성;강동명;이영상
    • 한국안전학회지
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    • 제11권1호
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    • pp.3-10
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    • 1996
  • The mechanical properties and fatigue crack growth rate fracture toughness of permanent mould cast austempered gray cast iron(AGI) were compared to those of sand cast AGI. Specimens prepared for tensile, impact and fatigue test were austenitized at $900^{\circ}C$ and austempered at $270^{\circ}C$, $320^{\circ}C$, $370^{\circ}C$ and $420^{\circ}C$ for 1 hour. The strength, impact and fatigue crack propagation behavior of permanent mold cast AGI were found to be superior to those of sand cast AGI. Maximum values in tensile strength, BHN, Charpy impact energy, were obtained at the austempering temperature of $270^{\circ}C$. Samely, the slowest fatigue crack growth rate was appeared at the austempering temperature of $270^{\circ}C$. But ductility of AGI was not improved by permanent mould casting.

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구상흑연주철재의 흑연에 의한 피로강도의 평가 (Evaluation of Fatigue Strength by Graphite in Ductile Cast Iron)

  • 이경모;윤명진;이종형
    • 한국정밀공학회지
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    • 제20권1호
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    • pp.214-221
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    • 2003
  • In this study, based on the effect of the interaction of fracture mechanics by graphite and fatigue limit phenomena of the microscopic observation various matrix structure, spheroidal ratio, size of graphite and distribution etc. parameters containd with Ductile Cast Iron. Therefore, in this study, different ferrite-pearlite matrix structure and spheroidal ratio of graphite of 70%, 80% and 90%, GCD40, GCD45-1 and GCD45-2 series and three different ferrite-pearlite matrix structure, GCD 45-3, GCD 50, GCD 60 series, all of which contain more than 90% spheroidal ratio of graphite, were used to obtain the correlation between mean size of spheroidal graphite and fatigue strength. (1) 73% pearlite structure had the highest fatigue limitation while 36% pearlite structure had the lowest fatigue limitation among ferrite-pearlite matrix. the increase in spheroidal ratio with increasing fatigue limitation, 90% had the highest, 14.3% increasing more then 10%, distribution range of fatigue life was small in same stress level. (2) (equation omitted) of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of (equation omitted) may be used as a guideline for the control of inclusion size in the steelmaking processes.

쉘 적층 주조 구상흑연주철의 기계적 성질에 미치는 합금원소 및 열처리의 영향 (Effects of Alloying Element and Heat Treatment on the Mechanical Properties of Ductile Cast Iron Poured into Shell Stack Mold)

  • 김효민;권민영;천병철;권도영;김기엽;권해욱
    • 한국주조공학회지
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    • 제40권3호
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    • pp.76-84
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    • 2020
  • The effects of Alloying Element and Heat Treatment on the mechanical properties of ductile cast iron poured into shell stack molds were investigated. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of tin and copper added, respectively. Those were greatly increased with the increased amount of tin added and the elongation was roughly decreased with it. In the simultaneous addition of copper and tin, the strength and hardness of the tin increased, but the elongation rate decreased. Those were greatly increased and this was decreased with normalizing. In the case of specimens with smaller section sizes during austempering processing, the strength and hardness were higher than those with larger sections, but the elongation rate was lower.

구상흑연주철의 마이크로 펄스 플라즈마 질화에 미치는 공정변수의 영향에 관한 연구 (A study on the Effect for Process Parameters on the Micro-pulse Plasma Nitriding of Ductile Cast Iron)

  • 김무길;이철민;권성겸;정병호;이재식;유용주;김기준
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권3호
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    • pp.43-51
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    • 2000
  • The effect of time, temperature and gas composition on the case hardened thickness, hardness and nitride formation in the surface of ductile cast iron(GCD400) have been studied by micro-pulse plasma technique. Typically, external compound layer and internal diffusion layer which is much thicker than compound layer was observed in the nitride hardening of ductile cast iron. The relative amount kind of phases formed in the nitrided hardening changed with the change of nitriding conditions. Generally, only nitride phases such as $\gamma^'$($Fe_4N$), or $\varepsilon$($Fe_{2-3}N$) phases were detected in compound layer by XRD analysis. The thickness of compound layer increased with the increase of nitrogen content in the gas composition. The optimum nitriding temperature was obtained at $520^{\circ}C$. The nitrided hardening thickness parabolically with nitriding time(t) and thus, the case hardened layer(d) fits well with the typical parabolic equation ; d=kt. The material constant k for GCD400 nitrided at $520^{\circ}C$ was $0.04919\times10^3{\mu}m.hr^{-1/2}$.

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회주철 판형 주조품의 공정 셀 수와 칠 깊이에 미치는 두께, 기본 원소 및 접종제의 영향 (Effects of Thickness, Base Element and Inoculants on the Number of Eutectic Cells and Chill Depth of Gray Cast Iron Plate Casting)

  • 김태형;오정혁;권해욱
    • 한국주조공학회지
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    • 제31권3호
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    • pp.137-144
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    • 2011
  • The effects of thickness, base element and inoculants on the number of eutectic cells and chill depth of gray cast iron plate casting were investigated. Meanwhile the number of eutectic cells increased by inoculation, chill depth decreased. The former decreased and the latter increased by holding the melt at the temperature range between 1,450 and $1,500^{\circ}C$. The former was more for the thinner casting with the thickness of 5 mm than the other. The result of thermal analysis coincided well with the change of macrostructure. The former increased and the latter decreased with the increased contents of carbon, silicon and the silicon content by inoculation. The former decreased and the latter increased with increased manganese content. The performance of the Superseed Extra was the best among 5 inoculants.

구상흑연 주철재의 피로크랙 발생 및 피로강도에 미치는 기지조직의 영향 (Effect of a Matrix Structure on the Initiation of Fatigue Crack and Fatigue Strength in Nodular Graphite Cast Iron)

  • 윤명진;이경모
    • 한국생산제조학회지
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    • 제7권5호
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    • pp.66-71
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    • 1998
  • It is required the superior materials for the parts of machines or structures, which could be endurable in severe load and environment. According to advancement of casting technology, nodular graphite cast iron is used as suitable for such condition. But nodular graphite cast iron is scattering of fatigue strength and low reliability. Therefore in this study, the effect of matrix structure and number of nodular graphite on the initiation of fatigue crack and fatigue strength. It was found that the material which has relatively high ferrite volume fraction was more easily cracked than other materials and fatigue limit was low. The material which has not found pinhole on the surface, the crack was initiated in graphite went through ferrite and propagated into through graphite, but separated graphite and ferrite grain boundary and combined with other cracks to fro large one.

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