Ultra-thin Fe–Si alloy sheet with excellent high frequency magnetic properties fabricated by partial decarburization combined with multi-stage cold rolling

• Published in: Scripta materialia 2023-02, Vol.224, p.115145, Article 115145
• Main Authors: Na, Jungkyun, Ko, Hyun-seok, Koo, Yangmo, Park, Semin
• Format: Article
• Language: English
• Subjects: Annealing; Electron backscattering diffraction; Magnetic properties; Soft magnetic materials; Texture
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2022.115145

Transformers with high operating frequencies are highly advantageous owing to their compact sizes. To improve their performance, we successfully fabricated ultra-thin Fe–Si alloy sheets using a novel partial decarburization and multistage cold rolling method. The sheets comprised a high volume fraction of uniform grains under 50 μm with 〈001〉 // rolling direction (RD) texture (78%) and displayed excellent magnetic properties at 20 kHz. Importantly, it was verified that core loss could be controlled by the growth of 〈001〉 // RD grains, and grain size was affected by the sheet thickness and annealing time. The 〈001〉 // RD grains were well developed for sheet thicknesses of 0.05mm–0.07 mm; however, under 0.05 mm, Goss grain growth was hindered by the thickness of the thin sheet. Our specimen achieved a core loss (P0.5/20,000) improvement of about 20% (4.54 W/kg) and one of the highest magnetic flux densities (1.80T) compared with commercial Fe-Si alloy sheets. [Display omitted]