Heatproof domain refining method using chemically etched pits on the surface of grain-oriented 3% Si-Fe

The experimental results of a new heatproof domain refining method for grain-oriented 3 % Si-Fe sheets are described. By using laser irradiation and nitric acid etching, small and shallow pits arranged in lines transverse to rolling direction were made on the surface of Si-Fe sheets. Typically the size of these pits was 0.3 mm in diameter and 0.02 mm in depth, spot distance was 0.3 mm and line distance was 5 mm. After recoating and stress relief annealing at 800°C for 2 hours, the iron losses of these Si-Fe sheets were reduced beyond 15 %. These materials reduce iron losses of wound type cores which need a high temperature annealing in the manufacturing.