Grain-Oriented (CRGO) › Standard CRGO › M4
M4 CRGO Steel0.27 mm conventional grain-oriented electrical steel for transformer cores
M4 is the AISI designation for 0.27 mm cold-rolled grain-oriented (CGO) silicon steel — a workhorse transformer-core grade with a guaranteed core loss of P1.7/50 ≤ 1.20 W/kg and induction B8 ≥ 1.85 T. It is the 0.27 mm gauge of our Standard CRGO line, cross-referenced to GB 27Q120, EN M120-27S and JIS 27G120, and supplied as coil, sheet, slit strip or stamped laminations with a mill test certificate.
By thickness & grade
M4 datasheet
Guaranteed values for fully-processed M4 (0.27 mm) grain-oriented steel, measured along the rolling direction. Certified per-coil test reports issued with every shipment.
| Parameter | Value | Test condition | Standard |
|---|---|---|---|
| Nominal thickness | 0.27 mm (0.0105″), tol. ± 4% | — | EN 10107 / GB/T 2521.2 |
| Core loss P1.7/50 | ≤ 1.20 W/kg guaranteed (≈ 1.11 W/kg typical) | 1.7 T, 50 Hz, Epstein | GB/T 3655 / IEC 60404-2 |
| Core loss P1.5/50 | ≤ 0.85 W/kg | 1.5 T, 50 Hz, Epstein | IEC 60404-2 |
| Magnetic induction B8 | ≥ 1.85 T | H = 800 A/m | GB/T 3655 / IEC 60404-2 |
| Stacking factor | ≥ 0.965 | — | IEC 60404-13 |
| Surface insulation | C5 inorganic coating (standard); C6 inorganic-organic on request | Franklin test | ASTM A717 |
| Silicon content | ≈ 3.1% silicon | — | — |
| Tensile strength | ≈ 340 MPa (rolling direction) | Room temperature | — |
M4 is the 0.27 mm member of our Standard CRGO line (0.23–0.35 mm, M3–M6). Some cross-reference tables map M4 to the tighter-loss EN M110-27S; confirm against your datasheet before design release. Need lower loss at 0.27 mm? Hi-B CRGO pushes P1.7/50 down to ≈ 1.00 W/kg — see our Hi-B vs standard CRGO payback comparison to check whether the premium is worth it for your core.
In hand
M4 CRGO steel master coil
0.27 mm · grain-oriented · full-hard coil · C5-coated, shipped with a mill test certificate on every coil.
M4 CRGO Steel — 0.27 mm CGO
0.27 mm · master coil
- Thickness0.27 mm (0.0105″)
- GradeM4 · conventional CGO
- Cross-reference27Q120 · M120-27S · 27G120
- Core loss P1.7/50≤ 1.20 W/kg
- Induction B8≥ 1.85 T
- Coil weightApprox. 5 t
- Coil inner diameter508 mm (610 mm on request)
- SurfaceC5 inorganic coating
- CertificateMill test certificate (EN 10204 3.1)
Grade equivalents
M4 across GB, EN, JIS & AISI
Working from a European or Japanese spec sheet? Use this cross-reference to match M4 to the equivalent code, or check the full chart for less common designations. Equivalence is a working guide, not full interchangeability.
Equivalents, at a glance
Technical & physical properties
Surface, tolerance and coil specifications
Beyond core loss and induction, these are the properties engineers usually ask for when qualifying an M4 coil.
| Surface insulation | C5 inorganic coating (standard) · C6 inorganic-organic on request |
|---|---|
| Stacking factor | ≥ 0.965 |
| Coil width range | 8–1,250 mm, slit to your width |
| Coil weight | Approx. 5 t per coil, mill or mother coil |
| Coil inner diameter | 508 mm (20″) standard, 610 mm on request |
| Thickness tolerance | ± 4% of nominal thickness |
| Width tolerance | ± 1.0 mm on slit strip |
| Tensile strength | ≈ 340 MPa (typ.), rolling direction |
| Test standards | GB/T 3655 & GB/T 2521 · IEC 60404 · EN 10107 · ASTM A343 / A876 |
By application
Matched to your core
Distribution transformers
Mitred step-lap cores where low no-load loss is a specified guarantee.
Explore →Power transformers
Stacked cores for medium and high-voltage units needing predictable exciting current.
Explore →Reactors & inductors
Shunt reactor and choke cores under continuous magnetizing current.
Enquire →Instrument transformers
Tight-tolerance CT/VT cores that must hold a stable accuracy class.
Enquire →Supplied forms
M4 as coil, sheet, strip or laminations
M4 is stocked as master coil and processed in-house to your order — cut to length, slit to width, or stamped to a lamination drawing.
01
Coil
Master and mill-edge coils, around 5 t, wound to your inner diameter and coil weight.
02
Sheet
Cut-to-length sheet in standard and custom lengths, ready for stamping or shearing.
03
Slit strip
Precision slit to width with tight tolerance, for stamping and C-core winding.
04
Laminations
Die-cut or laser-cut E-I, mitred and toroidal laminations to your drawing.
How we work
From enquiry to your dock
A simple path from spec to delivery, built for overseas buyers.
Send your spec
Thickness, grade, width and coating — or upload a drawing.
Quote in 24h
Matched grade, guaranteed loss and B8, availability in one business day.
Free samples
Test core loss and stampability, usually within a week.
Production & QC
Rolled, slit and tested coil by coil, with a mill certificate.
Export delivery
Moisture-proof packing and ocean freight to your port.
Packaging & export
Seaworthy packing to any port
01
Packaging
Coils in moisture-proof VCI wrap with edge and coil-eye protection; sheet and strip on corner-protected pallets.
02
Documentation
Mill test certificate, packing list, commercial invoice and certificate of origin; others on request.
03
Payment terms
T/T with 30% deposit and balance before shipment, or irrevocable L/C at sight.
04
Shipping & lead time
FOB Shanghai or Ningbo; CFR and CIF on request. 2–4 weeks production plus 25–45 days ocean freight.
FAQ
Sourcing M4 CRGO steel from us
What is M4 CRGO steel?
M4 is the AISI/ASTM designation for 0.27 mm conventional grain-oriented (CGO) silicon steel. Its grains are aligned to the rolling direction, giving low core loss and high permeability along that axis — the standard core material for power and distribution transformers at 50/60 Hz.
What thickness is AISI M4?
0.27 mm (0.0105″). The AISI M-number tracks thickness: M3 ≈ 0.23 mm, M4 ≈ 0.27 mm, M5 ≈ 0.30 mm, M6 ≈ 0.35 mm. If a document shows M4 at another gauge it is usually confusing the loss class with the thickness class — send the datasheet and we confirm.
What are M4’s core loss and induction values?
Guaranteed core loss P1.7/50 ≤ 1.20 W/kg (typically around 1.11 W/kg), P1.5/50 ≤ 0.85 W/kg, and induction B8 ≥ 1.85 T at 800 A/m, measured by Epstein frame along the rolling direction.
Can you match my GB, EN or JIS grade to M4?
Yes. As a working guide M4 ≈ GB 27Q120 ≈ EN M120-27S ≈ JIS 27G120. The Hi-B counterpart at the same thickness is 27QG100 / M100-27P / 27ZH100. Send your spec or datasheet and we confirm the match.
Is M4 conventional CGO or Hi-B?
M4 is a conventional grain-oriented (CGO) grade. If you need lower loss at 0.27 mm, the high-permeability option is 27QG100 / 27ZH100 (P1.7/50 ≤ 1.00 W/kg, B8 ≥ 1.89 T) at a higher price — see the Hi-B CRGO line. If you’re weighing whether that extra cost is worth it, our Hi-B vs standard CRGO payback comparison walks through the math with a worked example.
M4 or M5 — which should I choose?
M4 (0.27 mm) has lower loss and suits efficiency-driven distribution and power cores. M5 (0.30 mm) is a little cheaper per kg and easier to handle for larger, lower-frequency cores. Send your core size and no-load loss target and we advise.
What surface coating and tolerances do you offer on M4?
Standard C5 inorganic coating for interlaminar insulation; C6 inorganic-organic on request for punching or stress-relief annealing. Thickness tolerance ± 4% of nominal; width tolerance ± 1.0 mm on slit strip.
What is the minimum order quantity and lead time?
MOQ depends on width and form — slit strip and cut sheet run smaller than full coils. Common widths often ship from stock in days; non-standard widths typically take a few weeks. Free samples are usually ready within about a week.
Which standards and certifications apply?
Production runs under ISO 9001 and IATF 16949, with material to GB/T 2521, EN 10107, JIS C 2553 or AISI/ASTM and RoHS / REACH compliance. A mill test certificate ships with every order.
Why buyers choose Zhongxin
Mill-grade CRGO, export-ready service
Wuxi Zhongxin Special Steel Co., Ltd. is a Chinese manufacturer and exporter of grain-oriented silicon steel, serving transformer makers across Europe, the Americas, Asia and beyond.
Send your M4 spec — get a quote in 24 hours
Share your core loss target, thickness tolerance, width and form, or upload a drawing. Free samples available.
