• Journal of Korea Foundry Society
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• v.26 no.4
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• pp.180-183
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• 2006

The effects of adding Ni on microstructure and mechanical properties of Nodular Indefinite Chilled Iron (NICI) were studied. Thermal fatigue, hardness, tensile properties, wear resistance, are very important factors for NICI used for hot working roll and wire rod mill. The results show that addition 4% nickel has changed pearlite to bainite. Bainite matrix is superior to pearlite matrix on wear resistance, hardness and strength and will increase performance lifetime of NICI conventional roll material. Based in the bainitic microstructure, hardness and tensile property increase up to 48 HRc and $72\;kg/mm^2$, respectively.

• Journal of Korea Foundry Society
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• v.29 no.6
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• pp.251-256
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• 2009

The effect of austempering treatment on mechanical properties of nodular indefinite chilled iron(NICI) and ductile cast iron(DCI) was investigated. In microstructural observation, matrix phase(pearlite and ferrite) was changed to ausferrite after austempering treatment both DCI and NICI. In case of NICI, decomposition of cementite($Fe_3C$) during austempering treatment was induced. After austempering treatment, mechanical properties such as hardness, tensile strength and impact toughness was improved in NICI and DCI. The wear resistance is slightly decreased because of decomposition of cementite during austempering treatment in NICI but impact toughness and strength is dramatically increased.