Mo-Ni 계 구상흑연주철의 오스템퍼링 온도에 따른 파괴특성 = Fracture Properties on the austempering Temperatures of Mo-Ni Ductile Iron

다국어 초록 (Multilingual Abstract)

The fracture properties of ductile cast iron (DCI) can be significantly improved by austempering, isothermal transformation in the temperature range from Ar$quot; to Ar' point following austenitization. According to the results of experiment, when a 0.27%Mo-1.08%Ni alloyed DCI was austenitized for 1.5hr at 900 ℃ and austempered for 2hr at temperature range from 280 to 415℃, as the austempering temperature was increased, strength and hardness decreased, while ductility increased. Also, the fracture toughness values K_IC obtained were over about 80 MPa m＾(½) when yield strength, elongation and hardness were the ranges of 750 to 850 MPa, 5 to 8% and 270 to 330 H_B respectively. The homogeneous bainitic microstructure of the austempered ductile iron (ADI) was obtained by the austempering temperature range of 340 to 385 ℃, and its SEM fractography showed a fibrous structure of dimple pattern, and it had the high fracture toughness.

목차 (Table of Contents)

• 1. 서론
• 2. 실험방법
• 시편제작
• 열처리
• 파괴인성시험
• 3. 실험결과 및 고찰
• 기계적 성질 및 조직
• 파괴인성
• 4. 결론