• Title/Summary/Keyword: Cast nodular iron

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A Study on the Quality Control of Nodular Graphite Cast Iron (구상흑연주철의 품질관리에 관하여)

  • 강경식
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.5 no.6
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    • pp.55-62
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    • 1982
  • Mechanical characteristics of nodular graphite cast iron has found to tan higher utilization to the gray cast iron. So, Nodular graphite cast iron is used as a basic material in mechanical industry. Great demand of Nodular graphite cast iron is expected to increase due to the sharp development in mechanical and automobile industry. Therefore, Nodular graphite cast iron requires not only good quality product but experienced skills in manufacturing process. But there exist a lot of difficulties to manufacture nodular graphite cast iron than gray cast iron in manufacturing process. In this study, the following topics are studied for good quality product of nodular graphite cast iron. $\circled1$ Activities of managerial staff. $\circled2$ Qualite control method in manufacturing process. $\circled3$ Manufacturing process system. As a result of the study, a intensive Quality control activities should be applied and reinforced at each stage of manufacturing process rather that at the last stage of final product.

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Effect of the Number of Nodular Grains on Low Cycle Fatigue Life in Spheroidal Graphite Cast Iron (저사이클 피로수명에 영향을 미치는 구상흑연주철의 흑연입자수의 영향)

  • Kim, Min-Gun;Lee, Byeong-Hyeon;Yoo, Byung-Ho
    • Journal of Industrial Technology
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    • v.20 no.B
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    • pp.3-8
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    • 2000
  • Low cycle fatigue life of spheroidal graphite cast iron is determined by the morphological parameters of internal graphite. The aim of this study is to clarify the effect of the number of nodular grain of spheroidal graphite cast iron on low cycle fatigue life. Two specimens that have identical average nodular grain size by changing nodular grain volume fraction and different number of nodular grain count was tested. In this paper, the parameter governing fatigue life through fatigue test, the number of nodular grain seriously affect fatigue life and nodular grain size is no longer governing parameter of it.

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Effect of Various Steel Scrap on the Microstructures and Mechanical Properties of Ductile Cast Iron (주철의 재질에 미치는 각종 Steel scrap의 영향)

  • ;Sadato Hiratsuka
    • Resources Recycling
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    • v.9 no.1
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    • pp.15-20
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    • 2000
  • The effect of different kinds of steel scraps, the raw material in the manufacturing of nodular cast iron, on the microstructures and mechanical properties has been investigated Different grades were produced by changing the steel scraps. When nodular graphite cast iron was produced by using Zn rich steel scrap, such as galvanized steel sheet and auto body sheet, mechanical properties were deteriorated due to the decomposition of graphite, so close control must be maintained over this element. Tensile strength and hardness of nodular graphite cast iron which were manufactured by using Sb rich steel scrap were increased while elongation was decreased due to the increased amounts of pearlite within matrix. Mn and Cr contents in the structural steel sheet scrap or malleable iron scrap increased tensile strength and hardness of nodular graphite cast iron by facilitating the formation of pearlite.

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Growth Mechanisms of Graphite Spherulites in the Nodular Cast Iron and the High-pressure-treated Ni-C alloy (구상흑연 주철과 고압처리된 Ni-C 합금에서 구상화 흑연의 성장 기구)

  • Park, Jong-Ku;Ahn, Jae-Pyoung;Kim, Gyeungho;Kim, Soo-Chul
    • Analytical Science and Technology
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    • v.13 no.2
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    • pp.200-207
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    • 2000
  • The growth mechanisms of graphite spherulite both in the nodular cast iron and the high pressuretreated Ni-C alloy were investigated by SEM, HRTEM and EELS. The internal microstructure and lattice image of graphite spherulite extracted from Ni-C alloy were compared with those of graphite spherulite extracted from the nodular cast iron. The ratios of $sp^2$ and $sp^3$ bonding in the respective graphite spherulite measured by EELS, are compared each other. The graphite spherulite of Ni-C alloy had little internal defects and much $sp^3$ carbon species compared to that of the nodular cast iron. Present difference in microstructural features and bonding characters indicated that the graphite spheruites in the high pressuretreated Ni-C alloy grew by different mechanism compared with those in the nodular cast iron.

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

  • Yoon, Myung-Jin;Lee, Kyoung-Mo
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.7 no.5
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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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Change in Hardness and Microstructure with Quenching and Tempering of Ductile Cast Iron (구상흑연주철의 열처리에 따른 미세조직 및 경도 변화)

  • Jeong, Woo Chang
    • Journal of the Korean Society for Heat Treatment
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    • v.21 no.2
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    • pp.69-78
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    • 2008
  • Differences in hardness and microstructure between surface and area at 0.3 mm below the surface after quenching and tempering of ductile cast iron for rear planet carrier of automotive transmission have been investigated. Microstructure of ductile cast iron consisted of ferrite, pearlite, and nodular graphite. The amount of pearlite increased with going down to the half-thickness area. It was found that Cr and Mo segregated to the pearlite and the pearlite transformed to the harder martensite during quenching. The martensite was more resistant to the decomposition to ferrite and cementite during tempering because of segregation of Cr and Mo, resulting in the harder tempered martensite. Consequently, the hardness of the surface with less amount of pearlite, corresponding to the harder martensite in the quenched and tempered microstructure, was lower than that of the area at 0.3 mm below the surface.

The Effect of Matric of Nodular Graphite Cast Iron on Machinability in Lathe Turning (球狀黑鉛鑄鐵의 基地組織이 切削性에 미치는 影響 I)

  • 성환태;안상욱
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.74-81
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    • 1987
  • The orthogonal cutting method of the nodular graphite cast iron in the lathe turning, whose structure were formulated under two kinds of annealing conditions, has been experimentally studied and the results investigated. The various characteristics of machinabilities of the nodular cast iron, depending upon its structure, have been obtained from the results as follows. (1) As depth of cut increases, the shearing strain decreases and tend gradually to increase with increase of ferrite matrix. (2) As depth of cut increases, the shearing stress slightly decreases for P$_{1}$, but it tends to increase for both of P$_{2}$ and P$_{3}$ under the same condition. The annealing effect in the process of light cutting was found to be greater than heavy cutting. (3) The cutting energy slightly decreases with the increassing of the depth of cut, and the effect of decreasing the cutting energy by the annealing is higer the light cutting than the heavy cutting. (4) The cutting equations as follow. P$_{1}$ : 2.phi.+1.58(.betha.-alpha.)=92 deg. P$_{2}$ : 2.phi.+1.40(.betha.-alpha.)=84 deg. P$_{3}$ : 2.phi.+1.37(.betha.-alpha.)=82 deg. (5) The machining constants for P$_{1}$, P$_{2}$ and P$_{3}$ which are the test-pieces in this study and classified according to the containing quantity of ferrite matrix given respectively in 78deg., 70 deg., and 68 deg. From these it can be known that the machining constants slightly decreases with increasing of the quantity of ferrite matrix contained in the nodular graphite cast iron.

The Effest of Matrix of Nodular Graphite Cast Iron on Machinability in Lathe Turning - Cutting Force, Cutting Ratio and Shear Angle- (球狀黑鉛鑄鐵의 其他組織이 切削性에 미치는 영향 I)

  • 성환태;안상욱
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.6
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    • pp.807-813
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    • 1986
  • The orthogonal cutting method of the nodular graphite cast iron in the lathe turning, whose matrix were formulated under two kinds of annealing conditions, has been experimentally studied and the results investigated. The various characteristics of machinabilities of the nodular cast iron, depending upon its matrix, have been obtained from the results as follows. (1) As depth of cut increases, the cutting ratio and the shear angles tend to slightly increase, and as the containing quantity of ferrite matrix increases, they slightly decrease. (2) As depth of cut increases, the cutting force increases in an approximate straight line, and as the containing quantity of ferrite matrix increases, they decreases and the decreasing rate is about 20-30%. (3) As the containing quantity of ferrite matrix increases, the friction force acting on the tool face decreases and the decreasing rate is about 34-40% in case of the lower depth of cut, but in case of the higher depth of cut the decreasing rate is very small. (4) Both shearing force and vertical force show a lineal increases, and according as ferrite matrix increases there is a decrease by 25% in shearing force and a 12-25% decrease in vertical force. (5) Shearing speed and chip flow speed keep almost a constant value irrespective of matrix.

Study on Tribological Characteristics of Machine Component in Boundary Lubrication (경계윤활에서 기계 부품 소재의 트라이볼로지적 특성에 관한 연구)

  • Kim, Myeong-Gu;Seo, Kuk-Jin;Nam, Jahyun;Kim, Dae-Eun
    • Tribology and Lubricants
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    • v.35 no.6
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    • pp.356-361
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    • 2019
  • The friction and wear between machine components directly influence the energy loss and failure in various machines. Therefore, there is always a demand for finding methods to reduce friction and wear. Of the possible methods, lubrication is a widely used method for reducing friction and wear. In the case of lubrication, it is important to analyze the tribological behavior in the boundary lubrication because most of friction and wear occurs in the boundary lubrication regime. Cast iron has been regarded as a good material for industrial applications due to the excellent mechanical properties and high productivity. Especially, nodular cast iron is a material that shows better mechanical properties and wear-resistance compared with cast iron due to inclusion of spheroidal graphite. In this work, we investigated the tribological characteristics of nodular cast iron with respect to different counter parts in boundary lubrication regime. Sliding tests were conducted with SUJ2, ZrO2, Si3N4 balls as counter parts using a pin-on-disk type tribotester. The results showed different friction and wear behaviors with different counter parts. The case of ZrO2 showed the lowest wear rate in specimen and no significant ball wear. In case of SUJ2, it showed similar wear rate with ZrO2 case in specimen and the highest friction coefficient. The case of Si3N4 showed the lowest friction coefficient, 33% lower than the case of SUJ2. It showed 16.9 times larger wear rate in specimen and 43% larger wear rate in ball compared to that of the SUJ2 case.