Synopsis : The change in dislocation structure with recovery and recrystallization of 99.8% cold-rolled pure iron, Fe-0.3 mass%Al and Fe-0.3 mass%Si alloys was investigated by means of X-ray line profile analysis (XLPA) and TEM observation. In as-rolled samples of Fe-Al and Fe-Si alloys, the fraction of edge dislocation density increased in comparison with that in pure iron. In the early stage of recovery, dislocation densities with both edge and screw components remarkably decreased in pure iron, whereas in the Fe-Al and Fe-Si alloys, only the edge dislocation density distinctively decreased. This suggests that edge dislocations with relatively high density in as-rolled Fe-Si and Fe-Al alloys are easily annihilated by the climbing up motion of edge dislocations. In the late stage of recovery, the dislocation density of Fe-Si alloy did not decrease. No structural changes were observed by TEM which suggests that the recovery of Fe-Si alloy is strongly retarded, since Si hinders dislocation movement. In the early stage of recrystallization of pure iron, the formation of large subgrains was clearly confirmed in the lamellar structure. The subgrains show a similar orientation to the neighboring unrecrystallized grains, which represents similar behavior regarded as continuous recrystallization. Fe-Al alloy is similar to pure iron. Whereas, Fe-Si alloy exhibits discontinuous recrystallization in the sense that grains with low dislocation density were confirmed in the unrecovered lamellar structure with high driving force for recrystallization. This is because the Si strongly hinders dislocation movement. This effect agrees with the behavior of dislocation in Fe-Si alloy confirmed by XLPA.

Recrystallization Behavior and Texture Evolution in Severely Cold-rolled Fe-0.3Mass%Si and Fe-0.3Mass%Al Alloys Miho TomiTa, Tooru inaguma, Hiroaki SakamoTo and Kohsaku uShioda Synopsis : The effect of Si and Al additions on the recrystallization behavior of severely cold-rolled Fe by 99.8% reduction was investigated in comparison with a previous study on pure Fe 6). In Fe-0.3mass%Si alloy, recrystallized grain with {411} <011> and {411} <148> preferentially nucleated at an early stage of recrystallization, and the texture did not changed substantially with the progress of recrystallization, which supports the oriented nucleation theory. The {411} <148> texture significantly increased at the expense of recrystallized grains with {100} <023> and {322} <236> during normal grain growth. In Fe-0.3mass%Al alloy, dynamic recovery during heavy cold-rolling and substantial subgrain growth during low temperature annealing (350˚C) occurred, similar to the case of pure Fe and different from that of Fe-0.3mass%Si alloy. This is presumably because of the subtle influence of Al addition on cross-slip frequency and smaller solute-vacancy interaction as compared with Si addition. Furthermore, at the early stage of recrystallization, nuclei had similar orientations as cold-rolling texture. With the progress of recrystallization, {100} <012> and {111} <112> orientations intensified. In the following normal grain growth, {100} <012> texture intensified. However, the change in the texture during growth cannot be explained only by the size effect. A rigorous grain growth simulation model is required to explain the experimental facts by considering the dependency of grain boundary mobility and energy on grain boundary characteristics.

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