Mechanism of carbon influence on the transition from graphite to cementite eutectic in cast iron
Journal Title: Archiwum Odlewnictwa - Year 2010, Vol 10, Issue 2
Abstract
In this work an analytical solution is used to explain mechanism of carbon influence on the transition from graphite to cementite eutectic in cast iron. It is found that this transition can be related to (1) the nucleation potential of graphite (characterized directly by the cell count, N and indirectly by nucleation coefficients Ns and b) (2) the growth rate coefficient of graphite eutectic cell, (3) the temperature range, Tsc = Ts - Tc (where Ts and Tc is the equilibrium temperature of the graphite eutectic and formation temperature of the cementite eutectic respectively).and (4) the liquid volume fraction, fl after solidification of the pre-eutectic austenite. Method of estimation of Ns, b and values was presented. It has been shown that the main impact of carbon on the transition from graphite to cementite eutectic consist in increasing the eutectic cell count and growth rate of graphite eutectic cell. Analytical equations were derived to describe the absolute, CT relative chilling tendency, CTr and chill, w of cast iron.
Authors and Affiliations
E. Fraś, M. Górny
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