Experimental analysis has showed that during solidification of nodular cast iron under radial heat flow the nodule count initially decrease fromt eh surface but is related to solidification kinetics and is not so evident under unidirectional solidification. An analytical approach which permits the determination of solidification rates of slabs and cylinders is applied to analyse the differnce between cooling rates for both geometries. Analytical analysis has showed that solidification rate decreases continually under unidirectional heat flow. Otherwise, under radial heat flow the solidification rate initially decrease from the surface but change the behaviour increasing form midradius to centre. From the experimental nodule count and the analytical model a relationship between cooling rate and number of graphite nodules was stablished.
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