Issue 78

A. A. Frantsuzov et alii, Fracture and Structural Integrity, 78 (2026) 474-488; DOI: 10.3221/IGF-ESIS.78.27

To determine whether the agreement between ×500 and ×1000 reflects the real consistency of the reconstruction, rather than only a similarity of average grain-size distributions, the same region of the sample was mapped at different magnifications and the reconstructed PAG maps were overlaid. This same-area comparison provides a stricter validation criterion, because it evaluates whether individual reconstructed PAG boundaries coincide spatially. The overlay in Figure 9 shows that the ×500 and ×1000 reconstructions are in good agreement, with most PAG boundaries overlapping reliably, and the PAGS distribution (Figure 10) shows good correlation. This supports the use of ×500 magnification for this material, since it allows a larger area and a larger number of PAGs to be analyzed from a single EBSD map while preserving reconstruction reliability. In contrast, the ×3000 reconstruction overlay on ×1000 reconstruction in Figure 11 shows a tendency to subdivide some larger PAGs, up to approximately 15 μ m in diameter, into smaller fragments, indicating that excessive magnification does not necessarily improve reconstruction reliability.

Figure 9: a) EBSD map acquired at ×500 magnification; b) the same region acquired using four ×1000 EBSD maps.

To evaluate PAGS from the optically visible microstructure, the lineal intercept method was applied. Several randomly placed test lines were drawn on the etched micrographs, and at least 300 grain-boundary intersections were counted. The procedure was performed by two independent operators to assess the reproducibility of the method. A second manual approach was also used, based on measuring 300 individual grain diagonals on the same images. The resulting distributions are shown in Figure 12.

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