A Novel Technique for Improved Measurement of Graphite and Inclusions in Ductile Iron Contaminated by Boron

Abstract The highly heterogeneous microstructure of ductile iron in casting includes graphite particles, non-metallic inclusions, microporosity, and other features, such as carbides distributed in the ferrite–pearlite matrix. Determination and comprehensive quantification of microstructural features are practically important however challenging. An advanced methodology based on an automated SEM/EDX analysis was developed and compared to the standard optical imaging method. In addition to backscattered electron contrast, sensitive to atomic number, a novel methodology added EDX data to identify and classify the multiple structural features at micron resolution thresholding. To quantify the shape of individual phases, the eight chord raster algorithms was used and compared to standard metrology based on Feret diameter. A micropattern with regular shapes and the real microstructure of ductile irons with different boron concentrations and in section sizes from 5 to 30 mm were used for comparative studies. The advantages of this novel methodology were statistically proven.