Development of Boundary Misorientations During Grain Growth in Silicon Steels

Abstract

Changes in grain size, texture and misorientation distributions have been monitored during extensive normal grain growth in 3%Si steels. The boundary misorientation distributions deviate significantly from the Mackenzie relationship. Comparisons of correlated and uncorrelated distributions show large excesses of low angle boundaries. However, these are not a result of low energy boundaries being favoured during grain growth since the deviation diminishes as growth proceeds. The effect originates in the nucleation of grains in colonies of similar orientation during primary recrystallisation. A slight tendency for promotion of 60º boundaries may indicate some preference for the retention of lower energy twin boundaries during grain growth in silicon steel.

Mechanism of Secondary Recrystallization in Grain-Oriented Si Steel

“…Harase et al demonstrated that Goss grains have the highest frequencies of coincidence site lattice (CSL) boundaries in the matrix and claimed that selective growth can be explained by assuming the high mobility of CSL boundaries [7,8]. Hutchinson et al found the strong orientation dependence of Goss texture on the matrix texture in relation to CSL relationship [9]. On the other hand, Hayakawa and Szpunar assumed that high energy boundaries (misorientation angles between 20 to 45 degrees) are mobile instead of CSL boundaries [10].…”