Forsterite film formation and grain growth in 3% Si steel

The forsterite film in 3% Si steel is formed by a solid state reaction of the annealing separator, MgO, with SiO/sub 2/ that results from the reduction of the fayalite layer in the hydrogen atmosphere in the high temperature anneal. In this work, secondary recrystallization was about complete at 1000/spl deg/C. After that temperature tertiary recrystallization can occur if the boundary drag of the second phase particles can be overcome. Addition of phosphates to the annealing separator affects the morphology of the forsterite film and can have an important effect on tertiary recrystallization by affecting the rate of decrease of the boundary-drag and/or the surface energy relationship.<
>