IEC 60404-8-7:2017

Overview

IEC 60404-8-7:2017 is an international standard that specifies requirements for cold-rolled grain-oriented electrical steel strip and sheet supplied in the fully processed (final annealed) state. It applies to Goss textured grain-oriented electrical steel in nominal thicknesses of 0.23 mm, 0.27 mm, 0.30 mm and 0.35 mm, supplied as coils or sheets for the construction of magnetic circuits. The fourth edition (2017) updates the previous (2008) edition and extends the range to include improved grades.

Key topics

• Material classes: Defines two classes - conventional grades and high permeability grades (including domain refined variants). These correspond to Class C22 of IEC 60404‑1.
• Magnetic properties: Requirements for magnetic polarization and specific total loss (measured at 1.7 T, 50 Hz). The standard also prescribes how the steel name/designation is formed (includes a code based on 100 × specified max specific total loss).
• Geometric characteristics & tolerances: Nominal thicknesses, tolerances on width, length, edge camber, edge wave, residual curvature and burr height.
• Technological characteristics: Tests and limits for stacking factor, density, number of bends (ductility), internal stresses, and insulation coating resistance.
• Form of supply & delivery condition: Coils or sheets in the final annealed state, with surface condition and suitability-for-cutting requirements.
• Inspection & test procedures: Sampling, specimen preparation and test methods. Measurement references include IEC methods for Epstein frames and single sheet testers.
• Marking, labelling and packaging, plus procedures for complaints and purchaser information.

Practical applications

IEC 60404-8-7 is intended for organizations involved in the manufacture, specification, testing and use of grain‑oriented electrical steel:

• Transformer and reactor manufacturers specifying low-loss, high-permeability core steels to optimize efficiency and reduce core losses.
• Steel producers and slitters ensuring delivered coils/sheets meet magnetic, dimensional and surface tolerances.
• Quality and procurement engineers verifying supplier data, inspection reports and conformity to international requirements.
• Test laboratories carrying out magnetic loss, polarization and geometric measurements per IEC-referenced methods.

Benefits include consistent magnetic performance, predictable core losses, improved interoperability across suppliers, and clearer purchase and acceptance criteria for critical magnetic circuits.

Related standards

• IEC 60404‑1 (classification)
• IEC 60404‑2, IEC 60404‑3 (magnetic measurement methods - Epstein frame / single sheet tester)
• IEC 60404‑9, IEC 60404‑13 (geometrical and technological measurement methods)
• ISO 404, ISO 7799, ISO 10474 (general steel delivery and mechanical test references)

Keywords: IEC 60404-8-7, cold-rolled grain-oriented electrical steel, Goss texture, specific total loss, high permeability grades, electrical steel strip and sheet.