구상흑연주철의 오스테나이트 및 베이나이트의 변태거동 = A Study on the Transformation behaviors of Austenite and Bainite in Ductile Cast Iron

다국어 초록 (Multilingual Abstract)

The effect of austenitizing temperature and holding time at different austenitizing conditions on the behaviors of transformed austenite phase from ferrite in ductile cast Iron has been investigated. The formation behaviors of bainite formed by destablized isothermal heat treatment at 300℃, 400℃ after heating in the eutectoid transformation range(α+γ) for 1 hour were also, studied. Even the volume fraction of transformed austenite was same MVH(Micro Vicker's Hardness) of austenite formed at high austenitizing temperature has higher value than that of austenite at low temperature. The bainite phase began to form at interface of austenite and ferrite which carbon concentration is low relatively. This difference in the behaviors of transformed austenite seemed to be affected by the segregation of substitutional alloying elements and the change of carbon diffusion rate with various austenitizing conditions and austempering conditions.

목차 (Table of Contents)

• 1. 서론
• 2. 실험방법
• 시편제작
• 열처리
• 조직관찰, 경도 및 상분율 측정
• 3. 실험결과 및 고찰
• 가열온도 및 유지시간에 따른 오스테나이트 생성 거동
• 오스테나이트화 온도와 유지시간에 따른 오스테나이트 부피분율의 변화
• 가열온도와 유지시간에 따른 경도변화
• 베이나이트 생성과정과 변태거동
• 4. 결론