• Title, Summary, Keyword: Grey cast iron

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Effect of Austempering Temperatures on the Fractures Characteristic of Grey Cast Iron (오스템퍼링 처리한 회주철의 파괴특성에 미치는 오스템퍼링 온도의 영향에 관한 연구)

  • Kim, Chang-Gyu;Lee, Sung-Yul;Choi, Chang-Ock
    • Journal of Korea Foundry Society
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    • v.12 no.6
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    • pp.442-449
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    • 1992
  • Grey cast iron containing a small amount of Cu and Mo to improve the effect of heat treatment and microstructure were cast and them austenitized. After austenitizing the specimens of castings were austempered at 250$^{\circ}C$, 300$^{\circ}C$ and 350$^{\circ}C$. The effects of matrix structures on mechanical properties and fracture characteristics at the different austempering temperature were investigated. Tensile strength, hardness and impact toughness of austempered grey cast iron showed maximum valve 359 MPa, 321 HB, 3.9 CVN respectively at the lowest austempering temperature, 250$^{\circ}C$. $K_{IC}$ of gref cast iron at a austempering temperature, 250$^{\circ}C$, showed maximum 44 MPa.$m^{1/2}$ even though the amount of retained austenite in it is only 16%. This mainly comes from the refinement of the retained austenite. Quasi-cleavage pattern with a little fit of fibrous pattern was shown on the fractured surface of austempered grey cast iron at all of the temperatures tested.

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A Study on the Material Properties of Grey Cast Iron for Cylinder Liner Treated by Thermo Plastic Deformation Process (열소성변형공정을 시행한 회주철제 실린더 라이너의 재료물성에 관한 연구)

  • Kim Tae-Hyoung;Kim Jong-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.29 no.6
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    • pp.671-677
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    • 2005
  • In internal combustion engines the usual material for the cylinder liner is because of its good wear resistance Apparently this wear resistance arises from the at iron to form a hard glazed surface when under sliding friction. When the cylinder liner wear limits, it shall be replace with new one according to the classification soci manufacturer's standards. However, adoption of alternative repairing method such a metalizing, thermo plastic deformation process became inevitable taking enormous cost renewal into consideration. In this paper. the material properties of cylinder liner of grey discussed on the basis of the results of experimental work of the thermo plastic deformation the worn out cylinder liner made of grey cast iron.

Ultrasonic characterization of exhumed cast iron water pipes

  • Groves, Paul;Cascante, Giovanni;Knight, Mark
    • Smart Structures and Systems
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    • v.7 no.4
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    • pp.241-262
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    • 2011
  • Cast iron pipe has been used as a water distribution technology in North America since the early nineteenth century. The first cast iron pipes were made of grey cast iron which was succeeded by ductile iron as a pipe material in the 1940s. These different iron alloys have significantly different microstructures which give rise to distinct mechanical properties. Insight into the non-destructive structural condition assessment of aging pipes can be advantageous in developing mitigation strategies for pipe failures. This paper examines the relationship between the small-strain and large-strain properties of exhumed cast iron water pipes. Nondestructive and destructive testing programs were performed on eight pipes varying in age from 40 to 130 years. The experimental program included microstructure evaluation and ultrasonic, tensile, and flexural testing. New applications of frequency domain analysis techniques including Fourier and wavelet transforms of ultrasonic pulse velocity measurements are presented. A low correlation between wave propagation and large-strain measurements was observed. However, the wave velocities were consistently different between ductile and grey cast iron pipes (14% to 18% difference); the ductile iron pipes showed the smaller variation in wave velocities. Thus, the variation of elastic properties for ductile iron was not enough to define a linear correlation because all the measurements were practically concentrated in single cluster of points. The cross-sectional areas of the specimens tested varied as a result of minor manufacturing defects and levels of corrosion. These variations affect the large strain testing results; but, surface defects have limited effect on wave velocities and may also contribute to the low correlations observed. Lamb waves are typically not considered in the evaluation of ultrasonic pulse velocity. However, Lamb waves were found to contribute significantly to the frequency content of the ultrasonic signals possibly resulting in the poor correlations observed. Therefore, correlations between wave velocities and large strain properties obtained using specimens manufactured in the laboratory must be used with caution in the condition assessment of aged water pipes especially for grey cast iron pipes.

A Study on Iron-manufacture Method through Analysis of Ironware excavated from Byeokje, Goyang (고양 벽제 제철 유구 출토 철기의 분석을 통한 제철방법 연구)

  • Lim, Ju-Yeon;Kim, Soo-Ki
    • Journal of Conservation Science
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    • v.28 no.4
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    • pp.367-376
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    • 2012
  • The ironware production technology is a measure to fathom the society's level of development in time. To understand iron-manufacure methods in the past, various investigations on the fine structures and additions of ironware remains and Iron ingot have been conducted in a way of natural science. This study metallurgically reclassifies remains excavated in iron-manufacture remains located in Beokje, Goyang, which are thought to be in time of Goryeo Dynasty, and draws an inference from the element analysis on the iron-manufacture and smelting technology. Iron ingot samples with a cast iron structure are divided into those with a white cast iron structure and those with a grey cast iron rich in P. The P content of grey cast iron appeared to be the result of adding a flux agent like lime, iron ingot and carbon steel iron ingot with a cast iron structure excavated in the area is regarded as pig iron which was made without a refining process. In this study it seems that two methods of making ironware were used in the area; one is the method of making ironware by pouring cast iron to the casting, and the other is the method of making carbon steel through the refinement of pig iron. It appears that highly even steel structure of carbon steel and a small amount of MnS inclusion are very similar with that of the modern steel to which Mn is artificially added. Nevertheless, these data alone cannot be used to determine the source of Mn in the carbon steel of the excavated from the iron-manufacture remains, which raises the need for further studies on the source and the possibility of carbon steel via the iron-manufacture process of cast iron.

Friction Weldability of Grey Cast Iron - by the Concept of Friction Weld Heat Input Parameter - (회주철의 마찰용접 특성에 관한 연구 - 입열량 이론식을 중심으로 -)

  • Jeong, Ho-Shin;Bang, Kook-Soo
    • Journal of Welding and Joining
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    • v.32 no.3
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    • pp.95-101
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    • 2014
  • Joining of grey cast iron by fusion welding has much difficulties for its extremely low ductility and low toughness because of the flake form of the graphite. And the brittle microstructure, i.e. ledeburite may be formed during fusion welding by its rapid cooling rates. By these kinds of welding problem, preheat and post heat treatment temperature must be increased to avoid weld crack or welding problems. In order to avoid these fusion welding problem, friction welding of cast iron was carried out for improving joint soundness, establishing friction welding variables. There is no factor for evaluating friction weldability in continuous drive type friction welding. In this point of view, this study proposed the parameters for calculating friction weld heat input. The results obtained are as follows ; 1. There was a close relationship between tensile strength and flash appearance of friction welded joint. 2. Tensile strength was decreased and flash was severely oxidized as increasing frictional heating time. 3. As increased forging pressure $P_2$, flash had a large crack and tensile strength was decreased. 4. As powdered graphite by rotational frictional force induced flat surface and hindered plastic flow of metal, tensile strength of welded joint was decreased. 5. Heat input for continuous drive type friction welding could be calculated by the factors of $P_1$, $P_2$ and upset distance(${\delta}$).

High Toughness Silicon Nitride Material in Machining of Compacted Graphite Iron

  • Park, Kwon-Hee;Lee, Kern-Woo;Lee, Joo-Wan;Sharon, Moshe
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.861-862
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    • 2006
  • The suitable tools for CGI material has not been developed yet because of high hardness, high toughness and very low machininability compared to the grey cast iron. And the tool life has been decreased as the contents of Ti in CGI material. From this research, we were able to do the high speed machining by using high toughness silicon nitride ceramic tools. The silicon nitride ceramic tool grade was specially designed and prepared with microstructure of elongated grains with higher aspect ratio (c/a) than conventional one.

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Effects of Pouring Temperature and Alloying Elements on Damping Capacity and Mechanical Properties in 3.6%C Grey Cast Iron (3.6%C 회주철의 진동감쇠능 및 기계적 성질에 미치는 주입온도 및 합금원소 첨가의 영향)

  • Kim, J.C.;Baik, S.H.;Choi, C.S.
    • Journal of the Korean Society for Heat Treatment
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    • v.13 no.4
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    • pp.231-238
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    • 2000
  • Flake graphite cast irons with the high damping capacity have been used for the control of vibration and noise occurring in the members of various mechanical structures under vibrating conditions. However, the damping capacity which is morphological characteristics of graphite is one of the important factors in reducing the vibration and noise, but hardly any work has deal with this problem. Therefore, the authors have examined the damping capacity of various cast irons with alloying elements and studied the influences of the matrix structures, mechanical properties and morphological characteristics of graphite. The main results obtained are as follows: Effects of pouring temperature on the damping capacities and mechanical properties were investigated in 3.6%C cast iron. At $1400^{\circ}C$, specific damping capacity showed the maximum value, and decreased with increase pouring temperature. Mechanical properties showed opposite trend with the damping capacity. And then, effects of Ni on the damping capacities and mechanical properties have been investigated in 3.6%C gray cast iron. At 0.2%Ni content, specific damping capacity showed the maximum value, and decreased with further increase in Ni content. Graphite length also showed same behavior. This indicates that the specific damping capacity has a close relation with graphite length. In case of Mo addition in 3.6%C-0.2%Ni cast iron, specific damping capacity and tensile strength was 27% and $20kgf/mm^2$ at 3.6%C-0.2%Ni-0.3%Mo cast iron respectively.

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The effect of ball diameter upon surface accuracy in surface rolling with cast iron (주철의 서어피스 로울링에 있어서 가압 볼의 직경이 표면정밀도에 미치는 영향)

  • 허명규;최홍식;육광수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.5
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    • pp.1071-1082
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    • 1988
  • Surface rolling is one of the micro plastic processes which yields local deformation of surface, and improves surface roughness, hardness and fatigue strength. With the use of gray cast iron (GC 30) as material for experiment, the changes in surface roughness were investigated. A number of previous theses were refered to the effects of surface rolling for this study. With the use of steel ball of excellent in surface roughness and hardness, and with the applied force 20Kgf, surface rolling was performed. The summary of the experiment is as follows: (1) With the fixed applied force 20Kgf and the ball of 8.726mm in diameter, surface roughness was found to be the most excellent. (2) Increase in hardness was most prominent in the first rolling, but less effective in the succeeding rolling. (3) Reduction on diameter was affected by the previous process before rolling, and about 70 to 90% of reduction was made in the first rolling.