Nodule count is expressed as the number of graphite
nodules/mm2 and is performed at a magnification of 100×.
Generally, high nodule count indicates good metallurgical
quality, but there is an optimum range of nodule count for each
section size of casting, and nodule counts in excess of this
range may result in a degradation of properties. Nodule count
should be established between the manufacturer and the
purchaser. Figs. 8-10 compare the nodule counts of ductile iron
at 100 % nodularity, 90 % nodularity, and 80 % nodularity,
respectively