• Journal of Korea Foundry Society
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• v.6 no.4
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• pp.284-289
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• 1986

Decarburization phenomena have been studied by plasma in stainless steel, plain carbon steel and cast iron. It was also investigated the movement of impurity element P,S in the plasma jet metal pool. The plasma jet was obtained by $Ar\;-\;CO_2$ gas mixture with 5 kVA DC power source. It produced enough temperature to dissociate into activated oxygen atom by reaction of $CO_2{\leftrightarrows}CO+O^+$ and it reacted with ${\underline{C}}$ in metal pool. Decarburization rate was increased about 5 times in comparing with the conventional induction melted metal pool by $CO_2$ gas decarburization. Even under the Ar plasma jet, decarburization was obtained by agitation of metal bath by $Ar^+$ bombardment and dilution phenomena of carbon atom under the very high plasma temperature. But heavy element P and S are not much removed because they are too heavy in mass to be activated by $Ar^+$ion bombardment. Desulphurization was achieved by $Ar\;-\;CO_2$ plasma in plain carbon steel and cast iron by the reaction of $SO_2({\underline{S}}+O^+)$. But dephosphorization could not be obtained by $Ar\;-\;CO_2$ plasma, because gaseous reaction of phosphorous oxide (${\underline{P}}+O^+$) was not existed.

• Journal of Korea Foundry Society
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• v.15 no.3
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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.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.237-240
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• 2021

Failure of a suspension clamp made of hot dip galvanized cast iron in 154kV transmission tower was investigated. Metallurgical analysis of a crack of the clamp was performed using a digital microscope, an optical microscope, and a scanning electron microscope. It was revealed that the crack surface was covered by continuous zinc layer. Distinctive casting skin was found underneath both the outer surface and crack surface. The result showed that pre-existing crack had been formed in the fabrication, and liquid metal embrittlement during hot dip galvanization may assist crack propagation.

• Journal of Conservation Science
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• v.28 no.3
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• pp.257-264
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• 2012

Ancient mirrors are generally made of bronze, and it is very rare to find cases of iron mirrors excavated domestically. In this study, the unidentified ferrous artifact was treated for conservation, and was identified as a mirror. In this process, the sample was taken and analyzed for microstructure, and the manufacturing technology was studied. Analysis involved optical microscope, micro-hardness tester, and SEM-EDS. As the result of analysis, iron mirror structure exist not almost non-metallic inclusions, and partially network cementite was observed. This appears to have been caused by reduced carbon content due to decarburizing the cast iron in the solid state mirror which was created by cast iron. The ledeburite structure of the casting has difficult to cut or polish because has great hardness by high carbon content. Thus, the cast iron mirror was decarburized at a temperature under $850^{\circ}C$ with CO or $CO_2$ blocked, which reduced the hardness of the iron mirror and made it possible to polish the mirror surface. This deformation of structure according to carbon content results from such manufacturing technology.