| The effect of the graphite change and the structure of matrix makes a great difference in the properties of cast iron. Therefore the method to improve the properties of cast iron by inoculation treatment which adds Fe-Si, Ca-Si alloy just before the injection, has been studied and is being studied in these days. In this study, the increase of tensile strength by the effect of inoculation and solid solution strengthening, when the small amount of Al and Cu known as the element of graphitization was added, was studied. That is, the author increased the strength through refinement and homogenization of graphite which is caused by the addition of the graphitization elements, and through the change of the structure of matrix. The results obtained in this study were as follows; 1) The tensile strength showed an increase when the small amount of Al, Cu and Al-Cu alloy known as the graphitization elements were added just before the pouring. 2) In the case of Al addition, the cast iron with 0.75% Al showed 22% more increase in tensile strength in comparison with that without addition. 3) In the case of Cu addition, the cast iron with 1.2% Cu showed a maximum tensile strength, 37㎏/㎟, and 36% more increase in tensile strength in comparison with that without addition. 4) In the case of Al-Cu (1:1) alloy addition, the cast iron with 2.0% Al-Cu alloy showed a maximum tensile strength, and 48% more increase in tensile strength in comparison with that without addition. |
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