Abstract
In this study, graphitization mechanism promoted by aluminum was investigated. Cast iron melt containing aluminum (0.58 % , 1.20 % and 5.18 %) was discontinuously quenched to ice water from different stages of the solidification process. Microstructure of each specimen was observed, and carbon and aluminum was analyzed by XMA. Aluminum is concentrated to primary austenite and promotes its growth. In case of higher aluminum content, primary austenite is large and carbon content in residual melt is large on the beginning of eutectic solidification. Therefore graphitization starts on narrower grain boundaries of primary austenite and graphite grows along the grain boundaries. On the other hand, case of lower aluminum content, primary austenite is small and carbon content in residual melt is small on the beginning of eutectic solidification. Fine graphite flake is often observed with precipitated cementite.
