• Journal of Korea Foundry Society
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• v.3 no.4
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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.

• Journal of Korea Foundry Society
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• v.5 no.3
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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.

• Journal of the Korean Society for Nondestructive Testing
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• v.6 no.2
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• pp.17-36
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• 1987

In this experimental research, fracture mechanisms of spheroidal graphite cast iron (As Cast, annealed and normalized) were investigated by using Acoustic Emission (AE) technique. In this study, the data (AE signal) are digitized and processed with the 8 bits micro-computer (APPLE II) connected to the AE measuring device without data processing unit. The source of AE signal was estimated by fractography analysis. The results obtained in this experimental study are summarized as follows : For the heterogeneous materials (spheroidal graphite cast iron) with inclusions which may considered as cracks, it is found that low and high AE amplitude appear simultaneously and the load is found to be fluctuated in the final stage of deformation. But the lad is not fluctuated in tension test with low AE amplitude only. AE is measured within elastic region and it is confirmed that 0.2% offset yield load agrees approximately with the load point where AE counts decrease steeply after the point of maximum AE counts.

• Journal of Korea Foundry Society
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• v.15 no.6
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• pp.558-565
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• 1995

Effects of high Si-P addition on microstructure and mechanical properties of thin ductile cast iron have been investigated. The amount of silicon addition have fixed on 4.0wt% and the amounts of phosphorus addition and thickness of specimen have been varied from 0.05 to 0.8wt% and ${\phi}13mm$, ${\phi}10mm$ and ${\phi}6mm$, respectively. As the casting thickness decreased, the average diameter of spheroidal graphite was decreased and the hardness of the cast iron increased. By adding P, the average diameter of spheroidal graphite was increased and the count of the spheroidal graphite was decreased continuously. And the tensile strength and the elongation was decreased, and the hardness was increased. With the P added more than 0.2wt%, the abraded amount was decreased significantly. The addition of P improved the wear resistance and the hardness of thin ductile cast iron.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2353-2360
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• 2000

Statistical fatigue properties of metallic materials are increasingly required for reliability design purpose. In this study, static and fatigue tests were conducted and the normal, log-normal, two -parameter Weibull distributions at the 5% significance level are compared using the Kolmogorov-Smirnov goodness-of-fit test. Parameter estimation were compared with experimental results using the maximum likelihood method and least square method. It is found that two-parameter Weibull distribution and maximum likelihood method provide a good fit for static and fatigue life data. Therefore, it is applicable to the static and fatigue life analysis of the spheroidal graphite cast iron. The P-S-N curves were evaluated using log-normal distribution, which showed fatigue life behavior very well.

• Journal of Ocean Engineering and Technology
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• v.17 no.5 s.54
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• pp.76-81
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• 2003

Friction welding of GCD45 spheroidal graphite cast iron and 2024 aluminum alloy has been studied, especially in terms of the joint faces and strength of friction welding. For appropriate results of the friction welding of GCD45 graphite cast iron and 2024 aluminum alloy, an insert of A1050 pure aluminum metal was used. The joint strength of the A1050 pure aluminum insert approached the maximum strength of 165.7Mpa, compared to 128MPa for the joint between GCD45 graphite cast iron and A1050 pure aluminum without the insert metal. Maximum strength, 165.7Mpa, was possible for the following optimum conditions: 20MPa for the friction pressure, P1, 60MPa for the upsetting pressure, P2, 1 second for the friction time, t1, 3000rpm for the rotation, N, and 0.3 seconds for the brake time, tB.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.42-47
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• 2001

In this study, fatigue limit of ductile cast iron is evaluated based on phenomena of the microscopic observation, such as matrix structure, spheroidal ratio, size of graphite and distribution. Three different ferrite-pearlite matrix structure, GCD 45-), GCD 50, GCD 60 series, all of which contain more than 70% spheroidal ratio of graphite, were used to obtain the correlation between maximum size of graphite and fatigue strength. It was concluded as fellows. (1) In Ductile cast iron of ferrite-pearlite matrix, the fatigue limit of GCD 60 series with 73% pearlite structure was the highest. (2) From observation of the starting point of crack of all specimens, it is noted that the crack initiates, in graphite, goes through ferrite and propagates into pearlite. (3) A good quality of Ductile cast iron used in this experiment can be checked from uniformly distributed graphite. The negligible interaction effect between graphites was verified by microscopic observation and fracture mechanics investigation in surface and interior of the specimen.

• Laser Solutions
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• v.18 no.2
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• pp.1-4
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• 2015

This study is related to the surface hardening treatment to spheroidal graphite cast iron for die by using high power diode laser. Laser device used in this experiment is capable of real-time laser power control. This is because the infrared temperature sensor (two color pyrometer) attached to the optical system measures the surface temperature of specimen and adjusts the laser power in real time. The surface treatment was carried out with the change of heat treatment temperature at the beam travel speed 3 mm/sec. Hardened width and depth was measured and hardened zone was analyzed by micro vickers hardness test in order to research the optimum condition of heat treatment. The changes in microstructure of the hardened zone also was examined. As a result of hardness measurement and observations on microstructure of hardened zone, hardness increased over three times as compared with base metal because the martensite was formed on the matrix structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.61-64
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• 1995

Grinding has been adapted as a finishing process,which can carry out form and surface integrity at the same time. Recently, high efficient and precise grinding technique is required bacause the needs for functional parts such as silicon wafer,ceramic,and electric materials are increasing. Accordingly, the development of grinding wheel appropriate to that purpose is very important. So, in this paper we newly developed a diamond grinding wheel by applying the superior characteristics of spheroidal graphite of the cast iron sintered product. Especially, a electric resistance sintering method was applied in which rapid heat treatment is possible. Finally, we have achieved successful results that the grinding wheel has high hardness,durability and grinding ability,and satisfies above conditions.

• Journal of Korea Foundry Society
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• v.10 no.3
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• pp.225-234
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• 1990

Spheroidal graphite cast irons which are Fe-3%C-(4－6)%Si-(0－0.5)%Mo were studied to improve not only heat resistance but also mechanical properties. With increasing Mo content, the graphitization was decreased and carbide volume fraction was increased. The graphite spheroidization ratio was not decreased in Fe-3%C-6%Si-Mo system cast iron with increasing Mo content, but that was decreased in Fe-3%C-4%Si-Mo system and Fe-3%C-5%Si-Mo system cast irons. Hardness was increased with the Si and Mo contents. At constant Si content, tensile strength was increased with increasing Mo content, but that was decreased at 6%Si. In the experiment of oxidation, weight gain was decreased as the Si and/or Mo content increased, but increased at 1.5%Mo content.