n-radii Approach for Multi-scale Characterization of Graphite Shape in Cast Iron

Knowledge of multi-scale particle macro-shape and micro-surface topology is critical in many technical disciplines. Specifically, quality assessment of the shape of the graphite phase in cast irons is essential for day-to-day metal casting operations. Common methods for evaluating particle macro-shape have several drawbacks, often resulting in underestimation of sharp corners and surface texture. In this article, a method based on plotting n -radii from the center of mass to the perimeter and computing multi-scale topological characteristics is described and tested. Parametric tests, involving variations in the number of n -radii and image resolution, were performed to optimize the test parameters. The method was used to quantify different shapes of the graphite phase observed in industrial cast irons. A unified parameter of particle shape quality was proposed for the multi-scale characterization of particle shape, angularity and texture. The n -radii approach could be used in standards for the comprehensive evaluation of graphite shape nodularity, as well as for the characterization of various particulates.