Study of Sphericity and Compactness Parameters in Spheroidal Graphite Iron Using X-Ray Micro-computed Tomography and Image Processing

Abstract

This work focuses on the relation between the sphericity and compactness parameters obtained from the exhaustive analysis on the graphite nodules of a spheroidal graphite cast iron sample, in order to propose a methodology with allow establishing different quality categories of nodules. The experimental methodology involves X-ray micro-computed tomography on an ad hoc test sample to generate high-resolution 3D images and the processing/postprocessing of the resulting 3D images through several image analysis routines. Based on the evaluations of sphericity and compactness distributions of 9238 nodules, different quality categories, called subpopulations, are proposed. In addition, a threshold value for the sphericity parameter of the graphite nodules, which allows characterizing the graphite nodules of the highest quality, is identified. The results provide new insights for better understanding of the geometric characterization of graphite nodules and its distribution on spheroidal graphite cast iron by using the sphericity and compactness parameters. The methodology proposed is identified as a powerful tool to analyze, in a non-destructive way, not only the quality of spheroidal graphite cast iron parts with different size and geometry, but also other materials.