抄録
Diffusion induced recrystallization(DIR) has been studied by zincification of pure iron as well as interstitial free steel with particular attention on the local misorientation in grains caused by DIR. A change in microstructure was investigated as a function of annealing temperature from 723 K up to 963 K. Misorientation was measured using Electron Back Scattering Diffraction (EBSD) technique. Fine grains of ferrite nucleate on the surface of substrates considerably in the couples annealed at a higher temperature such as 963 K and complete a fine-grained surface layer. Boundaries between the fine grains are regarded as high angle boundaries since they are micro-etched strongly with the eventual formation of grooves along them. In contrast to the fine grains formed at a higher temperature, sub-grains form at a lower temperature such as 723 K and boundaries between sub-grains are regarded as low angle boundaries. The sum of local misorientation along a particular scanning direction, however, depends on the direction. The largest variation of misorientation in the original grains in which sub-grains caused by DIR exist is often observed along the scanning direction which terminates with high angle boundaries of original grains at least on one of its ends, while a smaller variation in misorientation is obtained along the direction which terminates with Σ or low angle boundaries on both ends. A possible interpretation of DIR is developed that the largest variation of misorientation leads high angle boundaries to be formed with the eventual formation of fine grains with high angle boundaries.
