• 한국주조공학회지
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• 제5권3호
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• pp.5-12
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• 1985

Many researchers have studied the eutectic solidification of CV Graphite Cast Iron qualitatively. However quantative studies have not been done. The type of eutectic solidification of CV Graphite Cast Iron treated with CG Alloy (Fe-Si-Mg-5Ti-Ca-Ce) was studied quantitatively through M.D.E. value (Mushy Degree of Eutectic Solidification) = $t_2/t_1)$, where $t_1$ is the difference of the eutectic solidification starting time between surface and center part of the casting sample, and $t_2$ is the time of eutectic solidification of the center part. Following results were obtained. (1) The M.D.E. value of CV graphite cast iron lies between that of spheroidal graphite and that of flake graphite cast iron but is closer to that of Flake graphite cast iron. (2) The M.D.E. value of CV graphite cast iron depends upon CV ratio. (3) The time required for eutectic solidification increases as graphite form is changed from Flake, CV. to spheroidal graphite. (4) The M.D.E. value increases as cooling rate increases.

• 한국주조공학회지
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• 제3권4호
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• pp.239-247
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• 1983

CV graphite cast iron has been studied and generally known to have properties close to the average values of those between flake and spheroidal graphite cast iron. However, the thermal diffusivity of CV graphite cast iron is much larger than that of the average value of those between flake and spheroidal graphite cast iron. In this study, an easy production method of CV graphite cast iron with small additions of a Al-Cu which is known as the element of the graphitization was investigated. The effects of hold time and of Al-Cu additions after the treatments with spheroidizer (Fe-Si-Mg alloy) were also investigated. Increasing the additions of a Al-Cu alloy, the holding time to form a CV graphite cast iron was decreasing. Tensile strength and thermal diffusivity (flash method) were measured in order to find the changes of the mechanical properties and the physical properties. Spheroidal, CV, and flake graphite cast iron have tensile strengths 46.44, 38.29, and $27.29\;kg/mm^2$ and thermal diffusivities $3.95{\times}10^{-6,}$ $8.41{\times}10^{-6}$, $8.81{\times}10^{-6}m^2/sec$, respectively at room temperature.

• 한국주조공학회지
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• 제1권2호
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• pp.2-9
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• 1981

Graphite spheroidization and scaling resistance of cast iron containing 5-10% Al were investigated. It is impossible to obtain spheroidal graphite in cast iron containing Al with 8 % and over, but possible to obtain spheroidal graphite even in cast iron with an Al content of about 10 % by increasing Si content. In the scaling test carried out under the heating condition of $950^{\circ}C$ in air for total of 50 hours, the scaling resistance of cast iron containing Al with 8 % and over was remarkably superior, and also spheroidal graphite cast iron was superior to flake graphite cast iron. The scale became thinner more compacts and more protective with increasing Al content.

• 한국주조공학회지
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• 제9권1호
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• pp.80-88
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• 1989

SGCI(Spheroidal Graphite Cast Iron), CVGCI(CV Graphite Cast Iron) and FGCI(Flake Graphite Cast Iron) having different contents of Mn($0.25%{\sim}0.85%$) and Ni($0.3%{\sim}1.2%$) were produced, respectively. The thermal expansion and thermal conductivity of the cast iron were investigated in the temperature range of $50^{\circ}C{\sim}300^{\circ}C$. As the graphite nodularity of the cast iron increases, thermal expansion coefficient increases, thermal conductivity and electrical conductivity to thermal conductivity ratio decrease. The thermal expansion coefficient of the cast iron increases with increasing Mn content and decreases with increasing Ni content. The thermal conductivity of the cast iron decreases with increasing Mn and Ni contents.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1041-1047
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• 2011

본 연구에서는 거의 모든 기반산업에서 필수적인 생산기술로 사용되고 있는 금형의 기계적 성질을 향상시키기 위해 고출력 다이오드 레이저를 이용하여 두 종류의 금형재료용 주철을 표면경화처리하였다. 우선, 구상흑연 주철인 FCD550 소재에 대하여 열처리 특성을 파악한 후, 편상흑연 주철인 HCI350 소재를 열처리하여 두 소재의 표면경화 특성을 비교하였다. 경화부의 경도는 두 시험편 모두 모재에 비해 3배 이상의 경도 상승을 보였지만, 재료에 포함된 흑연의 함유량 및 형상의 차이에 의한 재료의 열전도도에 따라서 FCD550 소재에 비해 HCI350이 열처리하는데 있어서 더 많은 입열이 요구되었다.

• 한국주조공학회지
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• 제6권1호
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• pp.20-26
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• 1986

In order to investigate the solidification characteristics of CV. graphite cast iron, decantation technique and thermal analysis test were used. Solidification characteristics were studied in the specimens with various compositions and graphite shape. The results were as follows; 1. The first surface solidifcation layer is formed along the mold wall by the growth of austenite dendrites in hypoeutectic composition and thin solid film in hypereutectic composition. 2. The mushy degree of solidifcation of hypereutiectic composition is higher than that of hypoeutectic. 3. In hypoeutectic, the effect of change of the mushy degree of solidification on the graphite shape is small, however, in hypereutectic the mushy degree of solidification becomes higher in order of flake, CV, and spheroidal graphite cast iron.

• 대한기계학회논문집A
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• 제35권12호
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• pp.1663-1668
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• 2011

자동차 차체를 제작하는 프레스 금형의 가공공정 중 제품의 형태를 완성하는 드로잉 공정 및 불필요한 부분을 절단하는 트리밍 공정은 그 공정의 특성상 금형의 마모가 심하기 때문에 금형의 내마모성을 향상시키기 위한 표면경화처리가 요구되고 있다. 따라서 본 연구에서는 프레스 금형에 레이저 표면처리기술을 적용하기 위한 실험을 실시하였다. 드로잉 공정 및 트리밍 공정에 적합한 표면경화처리를 위해 다이오드 레이저를 이용하여 시험편의 평면부 및 모서리부를 열처리하였으며, 각각의 적정 열처리 조건을 도출하였다. 또한 시험편의 재료에 따른 열처리 특성을 비교하기 위해 구상흑연 및 편상흑연 주철을 사용하여 실험을 진행하였다. 실험 결과, 재료에 따른 열처리 특성에 차이가 있다는 것을 확인하였으며, 적정 열처리된 조건에서의 경화부는 모재에 비하여 약 3배 정도의 경도상승을 나타내었다.