MORPHOLOGY AND DISTRIBUTION OF Nb-RICH PHASE AND GRAPHITE IN Nb MICROALLOYED DUCTILE IRON

摘要

The Nb-rich phase generated by the addition of trace amounts of Nb(<0.1wt%) and the effects of different content of Nb on the morphology and distribution of graphite in ductile iron were studied in this paper. The results showed that when the content of niobium less than 0.1wt%, the two-dimensional morphology of Nb-rich phase existed in microalloyed ductile iron were mainly regular pattern such as square, triangle, polygon etc. Besides, Nb-rich phase in large size distributed in the matrix with a certain distance from graphite. With the increasing amount of niobium, the dispersion degree of graphite diameter, average diameter and roundness increased slightly, and the number of graphite decreased slightly.