Effect of Heating and Cooling Rate on Growth of Flake Graphite Cast Iron

• Published in: Imono Vol. 64; no. 4; pp. 267 - 272
• Main Authors: Sohma, Makoto, Sugimoto, Yasukazu
• Format: Journal Article
• Language: Japanese
• Published: Tokyo Japan Foundry Engineering Society 25.03.1992; Nippon Imono Kyokai
• ISSN: 0021-4396; 2186-0335
• DOI: 10.11279/imono.64.4_267

To investigate effect of heating and cooling rate on growth of flake graphite cast iron, tests of growth were carried out in austenite (Gγ), transformation (Gα) and both (Gf) ranges with three heating and cooling rates of 1 K/min, 5 K/min and 10 K/min. The results obtained were as follows : (1) Growth in Gγ increased with the increase of heating and cooling rate. This was assumed to be the increase of degree of super cool and number of nucleus for redistribution of graphite according to the theory of irreversible graphite migration. (2) At the earlier stage of repeated heating in Gγ, the iron shrinked and slower rate leaded to greater shrinkage. This phenomenon was thought to be the shrinkage mechanism of cast iron heated isothermally in austenite range. (3) Growth of Gα and Gf decreased with the increase of heating and cooling rate. This was due to the decrease of direct and indirect graphitization. (4) Slower rate of heating and cooling leaded to greater growth of Gα and Gf in the earlier stage. But in the later stage effect of heating and cooling rates disappeared. (5) Growth in Gγ and Gf corresponded to growth in Gα though within the limited heating and cooling rates of this test. But this fact was a useful knowledge to the evaluation of growth of cast iron.