Role of Sn Content on Microstructure and Properties of Ultrathin Nonoriented Silicon Steel Ribbons Fabricated by Planar Flow Casting

The preparation of ultrathin nonoriented silicon steel ribbons by planar flow casting not only provides ribbons with a thickness of less than 0.1 mm directly from the molten alloy, but also creates a strong {100} texture. However, due to the poor wettability between the silicon steel melt and the copper wheel, the process window is narrow, increasing the risk of discontinuity and surface defects of ribbons, which is detrimental to magnetic performance. This study introduced Sn into Fe–3%Si to improve the wettability between the melt and the wheel, thereby broadened the processing window and obtained as‐cast ribbons with a relatively flat surface. Subsequently, heat treatment were carried out on as‐cast ribbons to optimize their magnetic performance. The results revealed that the addition of Sn did not cause significant segregation. The grain size of as‐cast ribbons gradually decreased from 16.24 to 10.61 μm and the ratio of {100} oriented grains increased from 33.9% to 40.3% as the Sn content increased from 0% to 0.5%. Both B 50 and P 1.0/400 increased with the increase of Sn content. The magnetic properties were significantly improved after annealing; the B 50 of the annealed ribbon with 0.5%Sn reached 1.67 T and the P 1.0/400 was 22.30 W/kg.