高Cr鑄鐵의 耐磨耗性과 衝擊靭性 向上에 關한 硏究 = A Study on the Improvement of Wear Resistance and Impact Toughness in High Cr Cast Iron

다국어 초록 (Multilingual Abstract)

High chromium cast irons have been well-known for their abrasive wear resistance. Its principal mechanical properties are high hardness and good impact toughness,. Generally, abrasion resistance increases with an increase of material hardness. The mechanical properties of Cr cast iron is influ-enced by microstructual factors such as the volume of carbide, carbide morphology and structure of matrix.
From this point of view, therfore, the purpose of this study was investigated in connection with the microstructual fators and the mechanical properties of Cr cast iron by destablized isothermal heat-treatment.
Conclusions resulting from this study are as follows ;
1. In case of destabilized isothermal heat-treatment at 400℃ and 1000℃, hardness was remakably increased since carbide area percentage was increased in matrix with rapid-cooling rate.
2. since eutectic carbide(M_7C_3) was grown toward colony boundary while matrix was strengthened by solution hardening of Cr and Si, good impact toughness was obtained by destablized heat-treatment at 800℃
.3. In fractographs of these specimens, small amount of dimple patterns was presented. but almost of them was observed typical qussi-cleavage fracture mode to be seen in brittle materials.
4. In the using of this high Cr cast iron (2.45% C, 16.51% Cr) for pulverizing mills, the suitable mechanical properties such as toughness, hardness and wear resistance were obtained by destablized isothermal heat-treatment at 800℃