Abrasion resistance of high nodule count ductile iron with different matrix microstructures

Thin wall ductile iron is being used in the industry as a way to improve the strength to weight ratio. Nevertheless, thin walled sections promote microstructural changes such as an important increase in the nodule count. This paper examines the influence of the nodule count on the abrasion resistance of ductile iron castings, having different matrix microstructures, and analyzes the main nodule characteristic affecting abrasion. Different ductile cast iron test samples, from 1.5 to 25 mm in thickness, having nodule counts varying between 250 and 2000 nod/mm2, were used. The samples for abrasion tests were heat treated in order to adjust the matrices to fully martensitic, ferritic, pearlitic and ausferritic microstructures. The abrasion resistance was evaluated according to the ASTM G 65 standard. The results showed that in all cases, when the nodule count increases the abrasion resistance decreases, as a consequence of the increase in total amount of nodules perimeter exposed to abrasion which increase the overall rate of wear.