THERMAL FLATTENING SEMI-PROCESSED ELECTRICAL STEEL

摘要

The thermal flattening of grain oriented silicon steel which is in the semi-processed condition has improved magnetic properties after a stress relief anneal by using a low temperature and high tension flattening anneal. The flattening process is conducted at a temperature between1000 to 1435.degree.F ( 540 to 780.degree.C ) with a tension selected to produce a yield strength / tension ratio from above 5 to about 20 and preferably from 7 to 13. The yield stength of the material will vary depending on the length of the time at peak temperature but are typically from 400 to 4000 psi (29,200 to 292,000 gm/cm2). The material as thermally flattened will have at least about10% stress. After a stress relief anneal above about 1450.degree.F ( 785.degree.C ), the material has significantly improved core loss compared to conventional thermally flattened material. The material is particularly suited for wound transformer core applications.