Insulation Coatings for Grain‐Oriented Electrical Steel: Mechanisms, Materials, and Future Directions

Grain‐oriented electrical steel (GOES) serves as the cornerstone soft magnetic material for high‐efficiency power transformers, which are critical for sustainable energy infrastructure. The performance of GOES is inextricably linked to its surface insulation coating, a multifunctional layer that provides electrical insulation while imparting a beneficial tensile stress to the steel substrate. This stress is paramount for refining magnetic domains and minimizing core loss. This review traces the technological evolution of these coatings, from early phosphate‐based layers to high‐performance, yet environmentally hazardous, chromate systems. The global regulatory pressure that has catalyzed the transition toward Cr‐free alternatives is critically examined, analyzing technologies such as composite oxides, organic–inorganic hybrids, waterborne polymers, nanocomposites, and advanced functional coatings. The fundamental mechanisms governing coating formation, stress induction, and magnetic property enhancement are elucidated with a focus on quantitative performance metrics. Finally, grand challenges and future research frontiers are identified, focusing on multifunctional coatings, ultra‐thin films for high‐frequency applications, sustainable manufacturing, and the integration of computational materials design. This review provides a comprehensive reference for the ongoing quest to develop next‐generation coatings that advance the performance of GOES and support global energy efficiency targets.