定速冷却した球状黒鉛鋳鉄のフェライト化

概要

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The effects of three rate-controlling factors, i.e. graphite nodule number, cooling rate and growth rate constants of the ferrite layer, on the ferritization rate of spheroidal graphite iron on linear cooling were investigated. The results of experiments on unidirectional growth of ferrite layers show that the growth rate constant of the ferrite layer in direct transformation during cooling is approximately proportional to the undercooling, and that proportional constant and the temperature at which ferritization starts vary with silicon and manganese content in iron. Ferritization of spheroidal graphite iron on linear cooling proceeds, in the beginning, by direct transformation as the undercooling increases, but it due to indirct transformation stops after pearlite is formed. The slower the cooling rate and the greater the graphite nodule number, the bigger is the ferritized fraction at the same undercooling. Based on these results, the ferritization process on linear cooling was numerically expressed. This was in good accord with the experimental results. By using the expression, the ferritized fraction after cooling can be evaluated.
Japan Foundry Engineering Societyの論文