M6 CRGO Steel0.35 mm conventional grain-oriented electrical steel for transformer cores

M6 is the AISI designation for 0.35 mm conventional cold-rolled grain-oriented (CRGO) electrical steel. Its grains are aligned to the rolling direction, giving low core loss and high permeability along that axis. It is the thickest and most economical of the M3–M6 series, used for transformer and reactor cores at 50/60 Hz.

0.35 mm (0.0138″), nominally 29 gauge. The AISI M-number tracks thickness: M3 ≈ 0.23 mm, M4 ≈ 0.27 mm, M5 ≈ 0.30 mm, M6 ≈ 0.35 mm. Our thickness tolerance on M6 is ± 0.030 mm.

Guaranteed core loss is P1.7/50 ≤ 1.55 W/kg — measured at 1.7 T and 50 Hz by Epstein frame along the rolling direction — with induction B8 ≥ 1.80 T at 800 A/m. Each coil ships with its own test values on the mill test certificate.

US spec sheets commonly quote M-6 at 1.5 T (15 kG) and 60 Hz in watts per pound — about 0.66 W/lb, roughly 1.46 W/kg. We guarantee at 1.7 T and 50 Hz, where the limit is ≤ 1.55 W/kg. These describe the same class of material under different test conditions, so the two figures cannot be compared directly. Send us your spec sheet and we confirm the match.

As a working guide M6 ≈ GB 35Q155 ≈ EN M150-35S ≈ JIS 35G155, all at 0.35 mm. Under the Indian standard IS 3024 the nearest grade is 35CG165. Loss limits differ slightly between standards, so send your spec or datasheet and we confirm the match — or check the full grade equivalents chart.

M5 (0.30 mm) has lower loss, P1.7/50 ≤ 1.30 W/kg against ≤ 1.55 W/kg for M6. M6 is thicker, so a core of the same height needs fewer laminations and stacks faster, and its stacking factor is slightly higher. Choose M5 when the no-load loss guarantee is tight, M6 when cost and build speed lead. Send your core size and loss target and we advise.

M6 is a conventional grain-oriented (CGO) grade. Our high-permeability grades run from 0.23 to 0.30 mm, so there is no Hi-B version at 0.35 mm. If you need lower loss, move to a thinner gauge — M4 or M5 — or to the Hi-B CRGO line.

Standard C5 inorganic coating for interlaminar insulation; C6 inorganic-organic on request. Thickness tolerance is ± 0.030 mm; width tolerance is ± 1.0 mm as rolled, tightening to ± 0.1–0.3 mm on slit-to-width coil.

Coil orders typically start at about 5 t — roughly one coil — and cut-to-length sheet from about 500 kg, both with a lead time of about 15 days. Smaller coil quantities are slit from a full coil and can take a few days longer when the grade is not in stock. For anything below these quantities, tell us the grade, size and quantity and we do our best to meet it.

Yes. Samples are usually ready within about a week, so you can test core loss and stampability first. The sample fee covers freight and is refunded against your first bulk order.