抄録
The morphological analysis of recrystallized grain structures of pure iron was carried out to make clear the relation between the structure and recrystallized condition. Specimens were prepared by cold rolling to the reductions of 60% and 80% and annealing at 650°C or 750°C for 10-240 min. Photographs of the microstructures in the longitudinal cross section parallel to the rolling direction were taken and grain boundaries were traced on paper for image processing. Average morphological characteristic values of 4πA/P2, LD/BR, CP/P were calculated for each grain structure, where A, P, LD, BR and CP represent the grain area, perimeter, the longest dimension, the narrowest breadth and convex perimeter, respectively. Coefficients of variation for the distributions of grain area were 1.0-1.3 and those for the distributions of grain size were 0.54-0.60. From the average values of 4πA/P2 and CP/P, it was shown that each grain in the structures for the 80% rolled specimens showed more stable shape than that for the 60% rolled specimens. Compared with the structures obtained by computer simulation study, the recrystallized grain shapes had anisotropy generated by the ellipsoidal growth with the axial ratio of 2.0 and the growth rate directed to the major axis of 0.2(unit length/unit time) at the nucleation rate of 100 (number/unit area·unit time). It was estimated that the anisotropy resulted from the anisotropic shape of nucleus.
