Abstract
The paper presents a fast and reliable image processing tool to characterize graphite nodules and casting defects in ductile cast iron (IAOGT – Image Analysis of Graphite Types). Relationship between ductility of ductile cast iron and size of casting defects and different characteristic nodule properties (graphite type, feret, nodularity and nodule count) are indicated by analysis of 33 tested tensile specimens. The casting defects and variation in nodule properties interact in a complex way but casting defects in the form of oxide films contribute most to low ductility. Low nodularity, low nodule count and high feret of graphite type III, IV-V also reduce ductility.

Key words
ductile cast iron, graphite types, casting defects, ductility, image analysis

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