Characteristic of Precipitate Evolution during High Temperature Annealing in Grain-Oriented Silicon Steel

Precipitate evolution during high temperature annealing plays an important role in the magnetic property of grain-oriented silicon steel but was rarely studied. Aluminum was one of the important components of precipitates. Grain-oriented silicon steels with three levels of aluminum content were prepared and the interrupted extraction experiments were carried out. The results showed that during high temperature annealing, the precipitates were polygonal with the main composition of (Al,Si)N. Both the distribution density and volume fraction of precipitates showed first increasing and then decreasing tendencies, while the precipitate size remained approximately constant at first and then increased. Aluminum had a significant effect on the density and volume fraction of precipitates, which resulted in different secondary recrystallization structures. A small amount of aluminum with 0.015 wt.% led to low precipitate density, resulting in a low onset secondary recrystallization temperature as well as a Goss texture with large deviation angles. With the aluminum content of 0.025 wt.%, the secondary recrystallization was developed exactly right in the optimum temperature range, resulting in a perfect magnetic property. When the aluminum content was overcommitted to 0.035 wt.%, Goss grains could not show the preferential growth advantage and the secondary recrystallization structure could not be well developed.