심랭 처리된 오스템퍼드 구상흑연주철의 기계적 성질에 미치는 Cu의 영향 = Effect of Cu on the Mechanical Properties of Subzero Treatmented Austempered Ductile Cast Iron

다국어 초록 (Multilingual Abstract)

This study was investigated the effect of the Cu addition and subzero treatment in austempered ductile cast iron. With increasing austempering time, volume fraction of retained austenite increased and is decreased after showed the peak value. Specimen with more Cu contents had a less quantity of retained austenite. Retained austenite transformed to martensite by subzero treatment. With decreasing subzero treatment temperature, retained austenite of specimens with more Cu contents transformed more Cu contents transformed more to martensite. With decreasing subzero treatment temperature the value of strength and hardness increased but the value of elongation and impact decreased. In this study, we could find that in subzero treated specimens an addition of Cu had a little of effect on the strength and the hardness but had very much effect on the value of the impact.