Effect of anneal coatings and surface condition on magnetic properties of grain oriented 3% Si - Fe

Reductions in high induction losses were obtained by annealing cold rolled, decarburized 3% Si-Fe samples with an Al2O3separator coating rather than MgO to obtain the final texture and properties. Reduced coercive force values were associated with the lower losses, and MgO coated samples exhibited subsurface oxide particles, while samples annealed with Al2O3had smooth surfaces. Similar low losses could be obtained in fully processed grain oriented samples by removing the mill coating by pickling and annealing at 1050°C with an Al2O3coating. Minimum losses were obtained in high permeability grain oriented samples by applying tension after a high temperature anneal with Al2O3coating.