Isamu Igarashi, Gorô Ôhira and Katsuro Nakamura
Mg is added to pure Fe-C alloy which contains 4.15% of C and 0.023% of Si, or to ordinary cast iron, then the cooling curve and microstructure of these alloys are studied and discussed. Mg suppresses the supercooling of both eutectic reaction, Fe-C and Fe-Fe3C. Ledeburite appears when Mg is added a little too much, but this disappears by an addition, of Si,especially an addition after Mg. Nodular graphite caused by addition of Mg is formed as an eutectic reaction from melt same as flaky graphite in normal cast iron, and for this formation the effect of Mg as gas state must be considered.
High C or Si is necessary to produce nodular graphite in ordinary cast iron and S prevents its formation.
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