Jong Soo Woo

Influence of primary annealing condition on texture development in grain oriented electrical steels

The development of texture and microstructure in two kinds of conventional grain oriented electrical steels, which were annealed at different primary annealing temperature, were investigated. The specimens were analyzed using Orientation Distribution Function (ODF), optical microscopy and OIM (Orientation Imaging Microscopy). The size distributions of AlN precipitates, which were used as grain growth inhibitors, were investigated using transmission electron microscope (TEM) and an image analyzer. The influence of primary annealing conditions on the secondary recrystallization in conventional grain oriented electrical steels was discussed based on information on precipitate distributions and the kinetics of abnormal grain growth of Goss grains. When the high energy boundary theory and the driving force for the Goss grain growth are considered, it is possible to explain the reason for significant improvement of the final texture and magnetic properties in the specimen that was recovered before the final annealing compared to the specimen that was recrystallized.

Influence of annealing before cold rolling on the evolution of sharp Goss texture in Fe-3%Si alloy

Abstract The primary grain size on annealing of cold rolled strips not preliminarily annealed before cold rolling was smaller than those annealed. In both cases, B 8 increased with increasing primary grain size and thus the main metallurgical function of annealing before cold rolling is to promote grain growth at the primary recrystallization stage and to increase B 8 values.

Stabilization and destabilization of domain wall positions in FeSi polycrystals using magnetic annealing effects

The effect of variation of magnetic annealing conditions on the properties of grain-oriented Fe-3%Si steels was investigated. It was shown that during magnetic annealing with special magnetizing conditions (in the B-range, corresponding to the stability of a large number of 90°-supplementary domains), the special magnetic structure is stabilized. This state is characterized by the increase of the sample magnetostriction in low and high fields as well as under compression, demonstrating the increased contribution of 90°-domain wall displacements and the magnetic domain structure rearrangement. The initial material state may be recovered using magnetic reannealing in the AC field by means of destabilization of induced changes in structure. Magnetic annealing in high DC fields yields an increase of preferred alignment of magnetic domains along the rolling direction and a pronounced magnetostriction decrease.