27QG100 0.27mm 1.00 W/kg Cold Rolled Grain-Oriented Silicon Steel Coil

What Is 27QG100 Grain-Oriented Silicon Steel?

27QG100 is a 0.27 mm thick cold-rolled grain-oriented (CRGO) silicon steel coil grade of the high-magnetic-induction (Hi-B) family, produced to the Chinese national standard GB/T 2521, with a guaranteed maximum specific total loss of 1.00 W/kg at 1.7 T / 50 Hz (P1.7/50) and a minimum magnetic polarization of 1.88 T at 800 A/m (B8). It is the standard workhorse grade for energy-efficient distribution transformer cores, renewable-energy step-up transformers and reactors, and is rolled by the leading Chinese mills within the China Baowu Steel Group (WISCO, Baosteel) as well as other qualified producers.

The grade designation follows the GB/T 2521 numbering system and encodes the full technical identity of the product:

• 27 — nominal strip thickness, 0.27 mm

• Q — grain-oriented (anisotropic) electrical steel, in which the easy magnetisation direction [001] of each crystal is aligned with the rolling direction

• G — high-magnetic-induction ("Gao Gan" high-permeability Hi-B) type, with secondary recrystallisation controlled to deliver B8 ≥ 1.88 T

• 100 — guaranteed maximum specific total loss of 1.00 W/kg, measured at magnetic polarization 1.7 T and frequency 50 Hz

Because 27QG100 is a non-domain-refined Hi-B grade, it occupies the cost/performance sweet spot of the 0.27 mm family: it delivers the high magnetic induction of Hi-B material at a materially lower price than laser-scribed (domain-refined) grades such as 27QH080 or B27R080, and — unlike those grades — it can be stress-relief annealed after slitting or cutting without destroying its loss performance. This combination makes it the volume grade of choice for wound cores, cut cores and large-batch distribution transformer production.

Key Specifications and Magnetic Properties

The table below summarises the guaranteed and typical magnetic properties of 27QG100. Guaranteed values are certified on the mill test certificate and form the contractual basis of supply; typical values represent normal production performance and are used for core design calculations.

Test conditions: P1.7/50 — specific total loss measured by the Epstein method at magnetic polarization 1.7 T, frequency 50 Hz; B8 — magnetic polarization at magnetic field strength 800 A/m. Values per GB/T 2521 and IEC 60404-8-7 test methods. Note that the Epstein frame measures magnetic polarization J (J = B − μ₀H); at 800 A/m the difference between B and J is 0.001 T.

Dimensional tolerances

Consistent thickness control directly determines the uniformity of the lamination factor and of core stacking height, which in turn governs the accuracy of the transformer's calculated no-load loss and noise.

Insulation coating

27QG100 is supplied with an insulating coating on both surfaces — typically an inorganic/chromate-based insulation (T-type, comparable to the S/T2 class used across the Baowu GOES family):

The coating provides inter-lamination insulation, edge-corrosion protection during storage, and sufficient weldability for core-welding operations.

Typical mechanical properties (longitudinal direction)

Mechanical values are typical production data and are not normally part of the magnetic guarantee; refer to the mill test certificate for the specific coil.

Standards and Grade Equivalents

27QG100 is produced and tested in accordance with the major international GOES standards. Because WISCO and Baosteel now both sit within China Baowu Steel Group, the same performance window is offered under parallel designations.

Note on equivalents: cross-mill grades with similar P1.7/50 and B8 windows are approximately interchangeable for many designs, but guaranteed values, coating systems and mechanical properties differ between mills. Always confirm the mill test certificate and the exact magnetic guarantee with the supplier before design freeze.

Grade family comparison (0.27 mm, typical values)

Two engineering steps are visible in this ladder. Moving from conventional 27Q120 to Hi-B 27QG100 cuts specific total loss by roughly 0.2 W/kg while raising magnetic induction from 1.80 T to about 1.90 T — a double benefit unique to the Hi-B process, which allows cores to run at higher design flux density with a smaller cross-section. Moving on to domain-refined grades buys a further ~0.17–0.2 W/kg reduction, but at a price premium and with processing restrictions (see below).

Why 0.27 mm Hi-B at 1.00 W/kg Is the Economic Sweet Spot

Eddy-current loss — the second major component of core loss — scales with the square of lamination thickness. Reducing strip thickness from 0.30 mm to 0.27 mm cuts the eddy-current component by approximately 19 %, other factors being equal, while 0.27 mm remains thick enough for high-speed slitting, step-lap cutting and automated core assembly without the fragility of 0.23 mm material.

Combined with the Hi-B microstructure, the 1.00 W/kg loss level of 27QG100 is sufficient to meet the core-loss budgets of mainstream energy-efficiency regimes:

• China GB 20052-2020 energy-efficiency levels for distribution transformers

• US DOE 2016 and the evolving NEMA Premium requirements

• EU Ecodesign Tier 2 (Regulation 548/2014) loss packages for distribution transformers

For designs targeting the very highest efficiency tiers, the domain-refined 27QH080-class grades offer the next step up; for everything else — which is the majority of global distribution transformer and renewable step-up volumes — 27QG100 offers the lowest total cost of ownership per watt of loss avoided.

Applications

1. Distribution transformer cores

The largest single application. 27QG100 is widely specified for oil-immersed and dry-type distribution transformer cores (10–35 kV class), where its balance of low loss, high induction and cost supports both efficiency compliance and competitive tender pricing.

2. Renewable-energy and storage step-up transformers

With the rapid build-out of photovoltaic and battery storage plants, compact box-type (prefabricated) step-up transformers and pad-mounted transformers are among the fastest-growing CRGO applications. The high B8 of 27QG100 allows a reduced core cross-section — directly relevant to the space and weight limits of containerised substations and skid-mounted power stations.

3. Wound cores, cut cores and toroidal cores

Because 27QG100 is not laser-scribed, its magnetic properties survive the stress-relief annealing that wound-core and cut-core manufacturing requires. This makes it the preferred grade family for toroidal transformers, C-cores and other wound constructions, where domain-refined material is normally excluded.

4. Reactors and instrument transformers

Medium and small power reactors, voltage and current transformers, and similar static electromagnetic devices, where consistent permeability along the rolling direction and low exciting current are required.

Processing and Handling Considerations

• Stress-relief annealing is permitted and often required. Cutting, slitting and winding introduce internal stress that degrades permeability and increases loss. A stress-relief anneal at 800 ± 10 °C in a protective atmosphere restores the magnetic condition. This is the key processing difference from laser-scribed (domain-refined) grades, which must NOT be re-annealed.

• Control cutting stresses. Use sharp tooling, keep burr height ≤ 0.025 mm, and avoid bending or kinking the strip — mechanical stress is the main cause of loss deterioration between coil and finished core.

• Respect the rolling direction. All magnetic properties are guaranteed along the rolling direction only. Cores must be designed so flux runs parallel to it.

• Keep the coating intact. Scratches, rust or contamination reduce inter-lamination resistance and raise local eddy-current loss.

• Store properly. Keep coils dry on their original skids; condensation promotes edge rust that is difficult to remove without damaging the insulation coating.

• Design flux density. 27QG100 operates economically at 1.65–1.75 T at 50 Hz; its Hi-B character gives more margin above 1.7 T than conventional CGO grades before exciting current and noise rise steeply.

How to Specify 27QG100 — Procurement Checklist

When sourcing 27QG100 coils, the following items should be agreed with the supplier and confirmed on the mill test certificate:

1. Magnetic guarantees — P1.7/50 (max) and B8 (min), per GB/T 2521 / IEC 60404-8-7 test methods
2. Mill origin — WISCO, Baosteel or other qualified producer; confirm which mill certificate will be supplied
3. Coating type — standard insulating coating; confirm annealing resistance if stress-relief annealing is planned
4. Edge condition — cut edge (EC) standard; mill edge where available
5. Dimensions — width (full width or slit), coil weight, coil inner diameter (508 mm standard), and whether vertical or horizontal eye-to-sky packing is required
6. Processing services — slitting, cut-to-length and re-packing for consolidated container shipping
7. Documentation — mill test certificate, packing list, and if required, third-party inspection (SGS, BV)
8. HS code note — coil is normally declared under HS 7226.11 (width < 600 mm) or 7225.11 (width ≥ 600 mm); confirm classification with your forwarder

FAQ

Q1: What does 27QG100 mean? The designation reads: 27 = 0.27 mm nominal thickness; Q = grain-oriented electrical steel; G = high magnetic induction (Hi-B) type; 100 = guaranteed maximum specific total loss of 1.00 W/kg at 1.7 T / 50 Hz.

Q2: Is 27QG100 the same as B27P100 or 27ZH100? They describe the same performance window — a 0.27 mm Hi-B grade with P1.7/50 ≤ 1.00 W/kg. B27P100 is the Baosteel designation, 27ZH100 is Nippon Steel's, and 27QG100 is the GB/T 2521 designation historically associated with WISCO. Guaranteed values and coatings differ slightly between mills, so always confirm against the mill test certificate.

Q3: Can 27QG100 be stress-relief annealed? Yes. As a non-domain-refined Hi-B grade, 27QG100 can be annealed at 800 ± 10 °C to remove cutting and winding stress. This is a key advantage over laser-scribed grades (27QH/B27R series), which lose their loss benefit if re-annealed — and the reason 27QG100 is preferred for wound and cut cores.

Q4: What is the difference between 27QG100 and 27Q120? 27Q120 is a conventional grain-oriented (CGO) grade: higher loss (≤ 1.20 W/kg) and lower induction (B8 ≥ 1.80 T). 27QG100's Hi-B metallurgy delivers both lower loss and roughly 0.1 T higher magnetic induction, allowing smaller, lighter and more efficient cores.

Q5: What widths and forms are available? Standard mill widths are typically 900–1200 mm, with slit coils available down to narrow widths for specific core designs. Supply forms include full-width coils, slit coils, cut-to-length sheets and transformer laminations.

Q6: Which efficiency regulations can 27QG100 cores meet? The grade supports mainstream efficiency levels under China GB 20052-2020, US DOE 2016 and EU Ecodesign Tier 2 for distribution transformers. For the most demanding ultra-low-loss designs, domain-refined grades (27QH080 / B27R080) provide the next performance tier.

Why Source 27QG100 from GNEE Steel?

GNEE Steel is a specialist supplier of grain-oriented and non-oriented electrical steel, supplying WISCO and Baosteel Hi-B and domain-refined grades to transformer and electrical equipment manufacturers worldwide. For 27QG100 we offer:

• Genuine mill material with full traceability — mill test certificates supplied with every delivery

• Flexible processing — slitting, cut-to-length, re-packing and export-grade seaworthy packaging

• Technical support — grade-selection guidance, core-loss comparison and material substitution advice (e.g. 27QG100 vs B27P100 vs 27QH080) from engineers familiar with transformer core design

• Global logistics — reliable delivery to ports worldwide with consolidated container options

Whether you are specifying material for a new distribution transformer platform, sourcing wound-core stock, or need a steady monthly supply of 27QG100 coils for production, our team can provide quotations, mill certificates and technical data sheets tailored to your specification.

Request a quote today — tell us your width, thickness tolerance, coil weight, coating requirement and destination port, and we will respond with a firm offer and current mill availability.

This article is provided for general information and is based on published standard data (GB/T 2521, JIS C 2553, IEC 60404-8-7) and mill family data. Guaranteed values, tolerances and coating properties vary by mill and production lot; always refer to the mill test certificate and confirm technical details with GNEE Steel before placing an order.