Which type of steel, known for high permeability, is used for manufacturing transformer cores?

• A. Silicon steel
• B. Carbon steel
• C. Stainless steel
• D. Tool steel

Answer: (A)

Transformer cores need a material that lets magnetic flux pass easily (high permeability) while keeping losses low. Silicon steel achieves this because adding silicon to iron increases the material’s resistivity, which reduces eddy current losses, and it preserves very high permeability so the magnetic circuit offers little reluctance. In practice, transformer cores are made from laminated sheets of silicon steel (often grain-oriented) to minimize energy loss while guiding flux efficiently. The other steels aren’t optimized for magnetic performance in this role: carbon steel lacks the silicon-driven permeability benefits and still has higher losses, stainless steel typically has lower permeability and higher losses in magnetic use, and tool steel is chosen for hardness rather than magnetic efficiency.