A new approach for the automatic evaluation of the solidification structure in steel using orientational entropy filtering
We present a new method for the automatic evaluation of the dendritic solidification structure in metallurgical micrographs of solidified steel. The evaluation of the microstructural parameters such as the primary dendrite arm spacing and the primary grain size are of high importance due to their direct relationship with the internal quality and mechanical properties of the cast product. Given the repeated geometric features in the micrographs and the regular pattern in colour intensity, we applied a filter mask to determine the local entropies within the masks in order to detect the centre coordinates of each individual dendrite. The orientation of the dendrites was determined by rotating the filter mask over each pixel to find the orientation which corresponds to the lowest entropy value. The segmentation of the microstructure was then performed via Delaunay tessellation and subsequent transformation of the triangular mesh into a rectangular grid, enabling the determination of the desired microstructural parameters.