(1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing,
Beijing 100083, China;2. Department of Product Development, Shougang Zhixin Qian′an
Electromagnetic Materials Co., Ltd., Qian′an 064404, Hebei, China)
Amount,size and species of precipitates are key factors affecting the magnetic properties of nonoriented electrical steels. An automatic scanning electron microscope (Aspex) is employed to analyze the precipitates in the annealed and hotrolled sheets of a commercial nonoriented electrical steel, finding that pure AlN and AlNMnS complex precipitates are the main precipitates. Precipitates distribute unevenly on the longitude section of annealed sheets where AlN and AlNMnS are larger and less in the center while smaller and more in the edge. The distribution of precipitates in the hotrolled sheets also shows the same rule with that in the annealed sheet. Samples with larger precipitates show larger grain size and better magnetic properties. Besides, nitriding layer is also verified to be detrimental to magnetic properties.