定量金属組織学を利用した球状黒鉛鋳鉄の凝固の研究

概要

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Microstructures in quenched specimens with Fe-Ni-C and Fe-C eutectic compositions were analyzed quantitatively in terms of fractional solidification, fraction and number of graphite nodules and average radius of austenite spheres. The order of magnitude and the temperature dependence of the growth rate constants of austenite spheres were consistent with the consideration that the growth is controlled by carbon diffusion inward through the austenite shell and there were almost no difference between Fe-Ni-C and Fe-C specimens. The computed number of graphite nodules in unit volume remained almost unchanged during solidification, and the fractional solidification measured was well expressed by the fraction of austenite spheres growing around the graphite nodules. Fractional solidification vs. time curves obtained by the analyses of cooling curves also showed good accordance with those determined in microstructures of quenched specimens. The pronounced tendency for undercooling and its gradual increase in later stages of solidification proved to be attributable to the diffusion controlled growth of austenite spheres and the number of spheres not being enough to compensate their slow growth.
Japan Foundry Engineering Societyの論文