The effect of Si on the relationship between orientation and carbide morphology in high chromium white irons

Electron back-scatter diffraction (EBSD) has been shown to be the most appropriate technique to study the orientation and carbide morphology of small (< 0.5 mu m) regions of microstructure of high chromium white irons. The carbides in a slightly hypo-eutectic Fe-Cr-C alloy show a distinct texture close to [<10(1)over bar 1>] whereas those in a 1.3 wt% Si commercial white iron have a diffuse texture, with regions near to major crystal directions, i.e., [0011], [<(1)over bar 2><(1)over bar 0>], [<01(1)over bar 0>], unpopulated. Using EBSD, it has been shown that the interconnectivity of the eutectic (Cr, Fe)(7)C-3 carbide is less in a 1.3 wt% Si alloy compared with a low (0.1 wt%) Si alloy. This reduced interconnectivity is consistent with the increased fracture toughness in the as-cast condition.