Grain-Oriented (CRGO) › Standard CRGO › 27Q120
27Q120 Electrical SteelThe Chinese GB grade for 0.27 mm grain-oriented silicon steel
27Q120 is the Chinese GB/T 2521 designation for 0.27 mm conventional cold-rolled grain-oriented (CRGO) electrical steel, with a guaranteed core loss of P1.7/50 ≤ 1.20 W/kg and induction B8 ≥ 1.80 T. Newer Chinese certificates may print the same grade as B27G120 or 27S120. It matches EN M120-27S, JIS 27G120 and AISI M-4, and we supply it as coil, sheet, slit strip or laminations, each shipment with a mill test certificate.
By thickness & grade
27Q120 datasheet
Guaranteed values for fully processed 27Q120 (0.27 mm) grain-oriented steel, measured along the rolling direction. Every shipment comes with a test report for each coil.
| Parameter | Value | Test condition | Standard |
|---|---|---|---|
| Grade names | 27Q120 (GB/T 2521, to 2016 edition) · 27S120 (GB/T 2521.2-2025 scheme) · B27G120 (Baosteel) | — | GB/T 2521.2 |
| Nominal thickness | 0.27 mm (0.0106″), tol. ± 0.030 mm | — | GB/T 2521.2 / EN 10107 |
| Core loss P1.7/50 | ≤ 1.20 W/kg guaranteed | 1.7 T, 50 Hz, Epstein | GB/T 3655 / IEC 60404-2 |
| Magnetic induction B8 | ≥ 1.80 T | H = 800 A/m | GB/T 3655 / IEC 60404-2 |
| Stacking factor | ≥ 95.0% | — | GB/T 19289 / IEC 60404-13 |
| Surface insulation | C5 inorganic coating (standard); C6 inorganic-organic on request | — | ASTM A976 |
| Density | 7.65 g/cm³ (conventional value used for testing) | — | IEC 60404-2 |
27Q120 is the 0.27 mm gauge of our Standard CRGO line (0.23–0.35 mm). If your drawing calls the grade M4, it is the same material — see M4 CRGO steel.
In hand
27Q120 slit coils, as supplied
0.27 mm · grain-oriented · C5-coated, slit to width in our workshop and shipped with a mill test certificate.
Master coil
Master coil, checked first
Each master coil is unwrapped and checked for surface, coating and edge condition before slitting.
- Coil weightApprox. 5 t
- Inner diameter508 mm (610 mm on request)
Slit coils
Slit to your widths
Master coil slit into several widths and wound into multi-strip coils on timber skids, ready for packing.
- Slit widthFrom 8 mm
- Width tolerance± 0.1–0.3 mm slit
Edge & surface
Edges and coated surface
Clean slit edges and an even grey insulation coating, checked before the coils are packed.
- Thickness0.27 mm ± 0.030 mm
- CoatingC5 standard · C6 on request
Grade numbering
How to read 27Q120 — and its new names
A Chinese grain-oriented grade code tells you the thickness, the type and the loss limit. The 2025 revision of the national standard and the large mills’ own standards now write the type letter differently, so one grade can arrive under three names.
27
Thickness
Nominal thickness × 100: 27 means 0.27 mm. Other gauges are 23, 30 and 35.
Q
Type
Q is conventional grain-oriented. QG marks high-permeability (Hi-B); RK marks domain-refined grades.
120
Loss limit
Maximum P1.7/50 × 100: 120 means core loss of no more than 1.20 W/kg.
New
27S120 · B27G120
GB/T 2521.2-2025 uses S for conventional; Baosteel writes B27G120. Same limit, same steel.
GB/T 2521.2-2025 took effect on 1 March 2026 and replaces the 2016 edition; its own example is 30S130 for a 0.30 mm conventional grade. Baosteel’s enterprise standard Q/BQB 485 allowed the old Q, QG and RK names to be used until the end of 2025.
Side by side
The 0.27 mm GB grades
At 0.27 mm the GB standard has two conventional grades and several Hi-B grades. 27Q120 is the conventional grade most often specified; when the loss target is tighter, the usual step is to 0.27 mm Hi-B rather than to a thinner gauge.
| GB grade | Type | 2025 scheme | Baosteel | EN / IEC | JIS | Core loss P1.7/50 | Induction B8 |
|---|---|---|---|---|---|---|---|
| 27Q120 | Conventional | 27S120 | B27G120 | M120-27S | 27G120 | ≤ 1.20 W/kg | ≥ 1.80 T |
| 27Q130 | Conventional | 27S130 | B27G130 | M130-27S | 27G130 | ≤ 1.30 W/kg | ≥ 1.80 T |
| 27QG120 | Hi-B | 27P120 | B27P120 | — | — | ≤ 1.20 W/kg | ≥ 1.88 T |
| 27QG100 | Hi-B | 27P100 | B27P100 | M103-27P (≈) | 27P100 | ≤ 1.00 W/kg | ≥ 1.88 T |
| 27QG095 | Hi-B | 27P095 | B27P095 | — | — | ≤ 0.95 W/kg | ≥ 1.88 T |
Watch the letters: 27QG120 has the same 1.20 W/kg limit as 27Q120 but is a Hi-B grade with B8 ≥ 1.88 T, so it meets a 27Q120 order and not the other way round. All five grades have a stacking factor of ≥ 95.0% at 0.27 mm. IEC 60404-8-7 adds a coating digit to the EN name (M120-27S5). Domain-refined 0.27 mm grades also exist; ask if your design calls for one. Hi-B grades are covered on the Hi-B CRGO page.
Grade equivalents
27Q120 across GB, EN, JIS & AISI
Working from a European, Japanese, American or Indian spec, or quoting against a Chinese tender? Use this list to match 27Q120 to the code on your drawing. It is a working guide, not proof of full interchangeability: test conditions and limits differ slightly between standards.
Equivalents, at a glance
How it’s measured
Reading the mill test certificate for 27Q120
Every 27Q120 coil ships with a mill test certificate listing its measured values by coil and heat number. Four points on a Chinese certificate tend to confuse overseas buyers; here is what each one means.
01
Core loss P1.7/50
Epstein test to GB/T 3655 (equivalent to IEC 60404-2) on samples stress-relief annealed at about 800 °C first.
02
J800 instead of B8
Newer certificates print polarisation J800. It differs from B8 by about 0.001 T, so read it as B8.
03
Grade column
27Q120, 27S120 or B27G120 all carry the same 1.20 W/kg limit, so check the measured value against it.
04
Reference values
P1.5/50 or P1.7/60 figures are for reference only; they bind only if your order names them.
More on test methods: Core loss testing with the Epstein frame →
Technical & physical properties
Surface, tolerance and coil specifications
Besides core loss and induction, engineers qualifying a 27Q120 coil usually ask for these properties.
| Surface insulation | C5 inorganic coating (standard) · C6 inorganic-organic on request |
|---|---|
| Stacking factor | ≥ 95.0% |
| Coil width range | 100–1,000 mm as rolled, slit to your width from 8 mm |
| Coil weight | Approx. 5 t per coil; other coil weights on request |
| Coil inner diameter | 508 mm (20″) standard, 610 mm on request |
| Thickness tolerance | ± 0.030 mm |
| Width tolerance | ± 1.0 mm as rolled · ± 0.1–0.3 mm on slit-to-width coil |
| Test standards | GB/T 3655 & GB/T 2521.2 · IEC 60404 · EN 10107 · ASTM A343 / A876 |
Ordering raw coil? Coil types, weights and edge conditions are covered on the CRGO steel coil page.
By application
Matched to your core
27Q120 sits in the middle of the conventional range. Its loss is lower than the 0.30 and 0.35 mm grades and it costs less than Hi-B, which makes it a common choice for distribution and medium power transformers.
Power
Medium power transformers
Substation and industrial units where the loss guarantee allows a conventional grade.
Explore →
Distribution
Distribution transformers
Three-phase and single-phase units built to national loss tables, including tenders written in GB grades.
Explore →
Dry-type
Dry-type transformers
Cast-resin and ventilated dry-type units for buildings and industrial plants.
Enquire →
Step-lap core
Stacked & step-lap cores
Mitred laminations for core shops building stacked and step-lap cores.
Enquire →Supplied forms
27Q120 as coil, sheet, strip or laminations
27Q120 is produced as master coil and processed in-house to your order: cut to length, slit to width, or stamped to a lamination drawing.
Coil
Coil
Master and mill-edge coils of around 5 t, wound to your inner diameter and coil weight.
Sheet
Sheet
Cut-to-length sheet in standard and custom lengths, ready for stamping or shearing.
Slit strip
Slit strip
Slit to your width on tight tolerances, for stamping and C-core winding.
Laminations
Laminations
Die-cut or laser-cut E-I, mitred and toroidal laminations to your drawing.
How we work
From enquiry to your dock
Five steps from your spec to delivery, set up for overseas buyers.
Send your spec
Grade in any standard, thickness, width and coating, or upload a drawing.
Quote in 24h
Matched grade, guaranteed loss and B8, and availability within one business day.
Samples
Test core loss and stampability; samples are usually ready within a week.
Production & QC
Every coil is slit and tested, and ships with a mill certificate.
Export delivery
Moisture-proof packing and ocean freight to your port.
Packaging & export
Seaworthy packing to any port
Wrap & edge guards
Wrapped and edge-protected
Moisture-proof wrap, inner and outer edge guards, and steel strapping on every coil.
Timber cradles
Strapped to timber cradles
Each coil sits on its own wooden cradle for forklift handling and stable stowage.
Container loading
Braced in the container
Coils are blocked with wooden dunnage and lashed so nothing shifts at sea.
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. Typically about 15 days to ship, plus 25–45 days ocean freight.
FAQ
Sourcing 27Q120 from us
What is 27Q120 silicon steel?
27Q120 is a Chinese GB/T 2521 grade of cold-rolled grain-oriented electrical steel. It is 0.27 mm thick and conventional (not Hi-B), with a guaranteed core loss of no more than 1.20 W/kg at 1.7 T and 50 Hz and B8 of at least 1.80 T. It is used for transformer cores at 50/60 Hz.
Is 27Q120 the same as M4?
Yes. M-4 is the AISI name for 0.27 mm conventional grain-oriented steel, and we supply both from the same material with the same 1.20 W/kg guarantee at 1.7 T and 50 Hz. US spec sheets often quote M-4 at 1.5 T and 60 Hz in W/lb, so their numbers look different. See M4 CRGO steel for that grade’s page.
My certificate says B27G120 or 27S120. Is that 27Q120?
Yes. B27G120 is Baosteel’s current name for the grade, and 27S120 follows the naming used in GB/T 2521.2-2025, which took effect on 1 March 2026. All three names mean 0.27 mm conventional grain-oriented steel with P1.7/50 ≤ 1.20 W/kg. If your tender or drawing still says 27Q120, the coil meets it as long as the measured loss is within that limit.
What is the difference between 27Q120 and 27Q130?
Both are 0.27 mm conventional grades with B8 ≥ 1.80 T. 27Q130 allows up to 1.30 W/kg against 1.20 W/kg for 27Q120, so its loss limit is about 8% higher. Choose 27Q120 when the transformer’s no-load loss guarantee is the binding constraint. Send your loss target and we confirm which grade fits.
Should I use 27Q120 or Hi-B 27QG100?
27QG100 is the high-permeability (Hi-B) grade at the same thickness: P1.7/50 ≤ 1.00 W/kg and B8 ≥ 1.88 T. It lowers no-load loss and lets the core run at higher flux density, but it costs more. 27Q120 is the cost-balanced choice when the loss table allows it. Compare both in Hi-B vs standard CRGO.
What is 27Q120 equivalent to in EN and JIS?
As a working guide, 27Q120 ≈ EN M120-27S (IEC M120-27S5) ≈ JIS 27G120 ≈ AISI M-4, all at 0.27 mm. Limits and test conditions differ slightly between standards, so send your spec or datasheet and we confirm the match. The full grade equivalents chart covers the other gauges.
What coating and tolerances do you offer on 27Q120?
C5 inorganic coating for interlaminar insulation is standard; C6 inorganic-organic is available on request. Thickness tolerance is ± 0.030 mm. Width tolerance is ± 1.0 mm as rolled and ± 0.1–0.3 mm on slit-to-width coil.
What is the minimum order quantity and lead time?
Coil orders typically start at about 5 t, roughly one coil, and cut-to-length sheet at about 500 kg. Lead time for both is 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 will do our best to meet it.
Can I get a sample of 27Q120 before ordering?
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.
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, supplying transformer makers in Europe, the Americas, Asia and beyond.
Send your 27Q120 spec — get a quote in 24 hours
Send your grade in any standard with your core loss target, width, form and quantity, or upload a drawing. Samples are available before you order.
