GB/T 21220-2007

This standard specifies the general requirements, magnetic properties, dimensional tolerances, and testing methods for pure iron, iron-silicon, iron-nickel, and iron-cobalt. The materials can be supplied in the form of rods, plates, sheets, strips, or wires, and these materials correspond to the alloy materials specified in IEC 60404-1 magnetic materials categories A, C1, C2, E1 to E4, and F1 to F3. Pure iron and steel, which are mainly used in relays, are covered by IEC 60404-8-10. However, the provisions on magnetic properties for pure iron (Category A) and iron-silicon (C21 and C22 categories) in IEC 60404-8-10 are less detailed than those in this standard, but it provides wider dimensional tolerances. Orientation-free and orientation-oriented silicon steel (C21 and C22 categories) used under 50/60 Hz are classified by their specific loss and are covered by IEC 60404-8-2, IEC 60404-8-4, and IEC 60404-8-7. Orientation-free and orientation-oriented thin magnetic materials used under medium frequency are classified by their specific loss and are covered by IEC 60404-8-8.