Influence of Annealing Atmosphere on the Morphology of Forsterite Film on the Silicon Steel Surface during Annealing

Forsterite on Hi-B steel surface forms by the reaction between an internal oxidized zone and MgO coating during high-temperature annealing. In this process, a large number of products degraded due to the cracking and spalling of the film. This experiment studies the influence of annealing atmosphere on the morphology evolution of oxidized zone and forsterite film. Results show the film is easy to fall off when the PO2 is low. Continuing to increase the PO2, there are unreacted silica particles remaining beneath the film. When the PO2 is very high, a thick and discontinuous film formed on the steel surface.