A common goal of the automotive industry is to improve fuel efficiency by designing and manufacturing lightweight cast components to meet environmental regulations and recent sustainability targets. To offset the weight benefit of light metal alloys, cast iron components are usually cast with close tolerances and minimum machining, retaining most of their as-cast surface. However, current research has shown that the surface microstructure can differ from the bulk microstructure, primarily due to mold-metal interaction phenomena. This surface deviation, mostly perceived as graphite degeneration for compacted and spheroidal graphite cast irons, stems mostly from Mg depletion at the interface. This phenomenon is mostly associated with the increased S and O concentration in the vicinity of mold and core interfaces due to S-based binders and residual humidity thermal decomposition. Following this, some observations have shown that complex particles - mostly sulfides and oxides - may form at the interface and potentially migrate into the bulk material 1-3) ; S and Mg concentration distribution profiles with increasing distance from the surface have also been measured 4, 5); however, the differences in particle populations between the bulk of the material and its interfaces against the mold and cores have not been statistically assessed. The present work aims to explore the possibility of using the EDAX Genesis software, based on automated particle analysis and X-ray spectra acquisition, using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS), respectively, to assess and quantify large particle populations. The method combines high-resolution imaging of SEM with semiquantitative analysis of EDS, focusing on sand mold-metal and core-metal interfaces and comparing them to the bulk material. The compacted graphite iron samples analyzed in this study were sourced from two distinct foundry facilities, each characterized by slightly different chemical compositions and process parameters.

References:

1. Holtzer, M., R. Dańko, and M. Górny, INT J CAST METAL RES, 2014, Vol. 29, pp. 17-25.

2. Svidro, J. T., International Foundry Research, 2010, Vol. 62, pp. 32-41.

3. Tsuda, M., et al., Journal of Japan Foundry Engineering Society, 1979, Vol. 51, pp. 383-388.

4. Ohide, T., Journal of Japan Foundry Engineering Society, 1999, Vol. 71, pp. 739-744.

5. Boonmee, S. and S. Rassamipat, INT J METALCAST, 2023, Vol. 18, pp. 480-493.