日本金属学会誌

J. Japan Inst. Metals, Vol. 57, No. 1 (1993),
pp. 119-124

Factors Affecting Tertiary Recrystallization of Thin Silicon Steel Sheets

Kazushi Ishiyama, Ken~Ichi Arai, Takashi Honda and Masaki Nakano

Research Institute of Electrical Communication, Tohoku University, Sendai

Abstract:

By using tertiary grain growth, thin grain oriented silicon steels having very low iron losses can be obtained. In this work, the effects of thickness of the samples, annealing temperature and atmosphere upon tertiary grain growth were observed.
The main findings were as follows.

(1) Before the beginning of tertiary grain growth, the grain growth behavior showed no differences between the grains having the (110) face and other faces. From this result, it was found that the motive force for grain growth before the beginning of tertiary grain growth was the boundary energy.

(2) Tertiary grains begin to grow after some induction period and grow at a constant rate. The higher the annealing temperature, the shorter becomes the induction period and the larger the growth rate of tertiary grains.

(3) In the samples having thinner thicknesses, the growth rate of tertiary grains becomes larger. One reason for the increase in motive force of tertiary grain growth is the increase in surface energy by the increase in area ratio between the surface and the grain boundary. Another reason is the increase in grain boundary energy because of the decrease in size of matrix grains around the growing tertiary grains.

(4) The growth rate of tertiary grain becomes smaller in the annealing atmosphere of low vacuum or hydrogen. This is due to the change in surface energy by the contamination of the sample surface.


(Received April 8, 1992)

Keywords:

(110)[001] texture, surface energy, grain boundary energy, grain growth rate, atmosphere, induction period


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