is the number of all of the graphite nucle- ation sites in the melt per unit volume, whereas b is defined by Eq.(10).


and b are not parameters that should be adjusted such as in expressions used in correlations in statistics. The nucle- ation coefficients Ns point of view, Ns


y b are well defined from the physical


is known [Li Dayong., Shi Dequan, Wang Lihua., “Monitor- ing of quality of vermicular cast iron from the front furnace”, Tsinghua Science Technology, vol.13, No 2., pp. 137-141,


The extent of undercooling for ductile iron is greater than for gray iron and this leads to the activation of smaller nucle- ation sites in ductile iron (Fig. IIa). In turn as the average site size la


diminishes, from equation (10) b increases. Besides, it


Authors: From our point of view, the nucleation coefficients Ns


likely that due to the spheroidization process the values of σ and θ will be increased in equation (10) and hence the value of b. Accordingly, the increase in the magnitude of b in ductile iron is not surprising (see Table 2).


(2008)] that when the spheroidizing process is employed, Mg is surface active element which increases the magnitude of the melt interfacial energy, σm


as opposed to gray iron. Thus, it is


Reviewer: Are nodules and eutectic cells counted in several locations in a single casting or does each count corresponds to a different casting?


Authors: Nodules / eutectic cells were counted in various plate shaped castings, located in a single mold and poured from one heat. The nucleation coefficients can also be deter- mined in several casting locations through the use of ther- mocouples at the different locations.


International Journal of Metalcasting/Summer 10


61


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