0.27mm 1.0 W/kg Grain-Oriented Electrical Steel Coil
Oct 21, 2026
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1. What Is 0.27mm 1.0 W/kg Grain-Oriented Electrical Steel?
0.27mm 1.0 W/kg grain-oriented electrical steel (abbreviated as 0.27mm 1.0 W/kg CRGO) is a high-grade cold-rolled grain-oriented electrical steel with a nominal thickness of 0.27 mm and a maximum specific core loss of 1.00 W/kg at 1.7 Tesla / 50 Hz (measured by the SST single sheet tester method). In the Chinese standard GB/T 2521.2, this material is designated as grade 27Q100.
Made from high-purity silicon-iron alloy (≈ 3.0–3.5 wt% Si) through cold rolling and high-temperature recrystallization annealing, the grains are highly oriented along the rolling direction, delivering excellent magnetic permeability and low core loss in that direction. The surface is coated with an S-type inorganic insulation layer, providing high inter-laminar insulation resistance and good stacking factor - making it the material of choice for energy-efficient power and distribution transformer cores.
As a mid-to-high grade CRGO, the 0.27mm 1.0 W/kg specification sits between conventional grades and high-permeability Hi-B grades, offering an optimal balance of performance and cost. It is widely used in 10kV–220kV class distribution and power transformers worldwide.
2. Key Specifications and Magnetic Properties of 0.27mm 1.0 W/kg CRGO
The table below lists the key magnetic properties of 0.27mm 1.0 W/kg CRGO (grade 27Q100), including both guaranteed and typical values:
| Property | Unit | Guaranteed | Typical |
|---|---|---|---|
| Specific core loss P₁.₇/₅₀ (SST) | W/kg | ≤ 1.00 | 0.90 – 0.95 |
| Magnetic induction B800 | T | ≥ 1.87 | 1.89 – 1.92 |
| Magnetic induction B50 | T | ≥ 1.78 | 1.80 – 1.83 |
| Stacking factor | - | ≥ 0.96 | 0.965 – 0.97 |
| Surface insulation resistance (per side) | Ω·cm² | ≥ 20 | 30 – 50 |
| Silicon content | wt% | 3.0 – 3.5 | 3.1 – 3.3 |
Note:
- Specific Core Losses: Max 1.00 W/Kg @ 1.7T / 50Hz (Based on SST method)
- Magnetic induction, B800, Tmin: 1.87 T(B800 is magnetic flux density at 800 A/m field strength.)
3. Dimensional Tolerances of 0.27mm grain-oriented electrical steel
Dimensional tolerances of 0.27mm grain-oriented electrical steel comply with GB/T 2521.2 and IEC 60404-8-7:
| Parameter | Tolerance or Value |
|---|---|
| Nominal thickness | 0.27 mm |
| Thickness tolerance | ± 0.02 mm |
| Width range (coil) | 900 – 1155 mm |
| Width tolerance | +1.0 / 0 mm |
| Coil weight | 3 – 5 MT (metric tons) |
| Coil inner diameter | 508 mm (20") ± 10 mm |
| Coil outer diameter | 1300 – 1600 mm (typical) |
| Camber | ≤ 1.5 mm / 2000 mm |
4.S Type Insulation Coating of 0.27mm 1.0 W/kg CRGO
0.27mm 1.0 W/kg CRGO is coated with an S-type inorganic insulation layer, offering good heat resistance and inter-laminar insulation performance for standard transformer core manufacturing:
| Coating Property | Value |
|---|---|
| Coating type | S-type (inorganic / semi-organic) |
| Coating weight (per side) | 0.8 – 1.5 g/m² |
| Surface insulation resistance | ≥ 20 Ω·cm² / side (IEC 60404-11, Franklin tester, 22°C±2°C) |
| Adhesion | No peeling after 180° bending (10mm mandrel) |
| Heat resistance | Stable up to 500°C (short-term) |
| Stress-relief annealing compatibility |
Not recommended (for S-type; use C-type if annealing needed) |
Note：
Surface Insulation Resistance: Minimum 20 Ω·cm² per side;
Test Method: IEC 60404-11 (Franklin tester, 22°C ± 2°C)
5. Typical Mechanical Properties (Longitudinal)
The table below shows typical longitudinal mechanical properties of 0.27mm 1.0 W/kg CRGO, for design reference only:
| Property | Typical Value |
|---|---|
| Tensile strength Rm | 420 – 480 MPa |
| Yield strength Rp0.2 | 340 – 400 MPa |
| Elongation A80 | 12 – 18 % |
| Hardness (HV) | 160 – 190 HV |
| Density | 7.65 g/cm³ |
| Resistivity (20°C) | ≈ 48 μΩ·cm |
6. Standards and Grade Equivalents
0.27mm 1.0 W/kg CRGO corresponds to the following grade designations in different national and international standards:
| Standard | Corresponding Grade | Note |
|---|---|---|
| GB/T 2521.2 (China) | 27Q100 | P₁.₇/₅₀ ≤ 1.00 W/kg |
| IEC 60404-8-7 (International) | 100-27P | 100 W/kg class, 0.27mm, fully processed |
| JIS C 2553 (Japan) | 27P100 | P-type, 0.27mm, P₁.₇/₅₀ ≤ 1.00 W/kg |
| ASTM A976M (USA) | Grade 100 (0.27mm) | Grain-oriented, 0.27mm nominal |
| EN 10106 (Europe) | M100-27P | 100 series, 0.27mm, fully processed |
7. Grade Family Comparison (Typical Values)
Performance comparison of different grades within the 0.27mm grain-oriented electrical steel family:
| Grade | Thickness | P₁.₇/₅₀ (W/kg) | B8 (T) | Type |
|---|---|---|---|---|
| 27Q120 | 0.27 mm | ≤ 1.20 | ≥ 1.85 | Conventional GO |
| 27Q100 | 0.27 mm | ≤ 1.00 | ≥ 1.87 | High-grade GO |
| 27Q090 | 0.27 mm | ≤ 0.90 | ≥ 1.88 | High-grade GO |
| 27Q085 | 0.27 mm | ≤ 0.85 | ≥ 1.89 | Hi-B (high permeability) |
| 27Q080 | 0.27 mm | ≤ 0.80 | ≥ 1.90 | Hi-B (high permeability) |
8. Applications of 0.27mm 1.0 W/kg grain-oriented electrical steel
0.27mm 1.0 W/kg grain-oriented electrical steel is widely used for core manufacturing in the following transformer and reactor applications:
Distribution Transformers
10kV–35kV oil-immersed and dry-type distribution transformers, meeting Tier-2 efficiency standards and above.
Power Transformers
110kV–220kV power transformer core limbs and yokes, balancing no-load loss and manufacturing cost.
Renewable Step-Up Transformers
Pad-mounted step-up transformers for wind and solar farms; suitable for outdoor and long-term low-load operation.
Reactors & Instrument Transformers
Shunt reactors, current-limiting reactors, and electromagnetic voltage/current transformer cores.
9. Processing and Handling Considerations
To ensure the magnetic properties of 0.27mm 1.0 W/kg CRGO are preserved after processing, strictly observe the following handling requirements:
- Do not stress-relief anneal S-type coated material. Use C-type heat-resistant coating grade if annealing is required in your process.
- Do not cut with blunt tools. Dull blades cause burrs and residual stress, degrading stacking factor and increasing core loss.
- Do not bend or dent the laminations. Mechanical deformation causes local magnetic property deterioration.
- Do not expose to corrosive environments. Avoid long-term storage in humid or corrosive atmospheres to prevent coating and substrate corrosion.
- Do not use welding inside the coil. Internal weld splices are prohibited; use dedicated splicing tape if joining is needed and record the position.
Note：Welding Points: Zero. The coil shall contain no internal weld splices.
10. How to Specify 0.27mm 1.0 W/kg CRGO – Procurement Checklist
Before placing an order, confirm the following technical terms to ensure the delivered material fully meets your production requirements:
- Grade & Standard: 0.27mm 1.0 W/kg CRGO (e.g. China grade 27Q100), confirm applicable standard (GB/T 2521.2 / IEC 60404-8-7 / JIS C 2553 / EN 10106).
- Thickness & Width: Confirm 0.27mm thickness, required width (900–1155mm range), and tolerance requirements.
- Core Loss: P₁.₇/₅₀ ≤ 1.00 W/kg, specify test method (SST or Epstein).
- Magnetic Induction: B800 ≥ 1.87 T minimum; upgrade to Hi-B grade if higher B values are required.
- Coating Type: S-type (standard) / C-type (heat-resistant), with insulation resistance ≥ 20 Ω·cm² per side.
- Coil Parameters: Coil weight (3–5 MT), inner diameter (508mm), packaging (vertical / horizontal).
- Quality Documents: Mill Test Certificate (MTC), core loss test report, coating inspection report, factory inspection certificate.
11. Why Source 0.27mm 1.0 W/kg CRGO from Us?
🏭Mill-Direct Supply
Long-term partnerships with leading CRGO mills in China; first-hand source with stable, traceable quality.
📏Precision Slitting
High-speed slitting & cut-to-length lines; custom widths with tight tolerances and minimal burrs.
🔬Full Inspection
Every coil ships with an SST core loss test report; pre-delivery re-inspection guarantees spec compliance.
🚢Global Shipping
FOB / CIF / DDP trade terms; sea-worthy packaging exported to 50+ countries worldwide.
Need a quote or sample testing for 0.27mm 1.0 W/kg grain-oriented electrical steel? Contact our technical sales team today
FAQ
Q1: How is core loss measured for 0.27mm 1.0 W/kg CRGO?
A: The guaranteed core loss value is measured by SST (Single Sheet Tester) according to IEC 60404-3. The SST method uses a single square sheet sample and better reflects the magnetic properties of actual processed strips.
Q2: Can 0.27mm 1.0 W/kg CRGO be stress-relief annealed?
A: Stress-relief annealing is NOT recommended for standard S-type coated 0.27mm 1.0 W/kg CRGO. High-temperature annealing (700–800°C) damages the S-type inorganic coating and reduces inter-laminar insulation resistance. If stress-relief annealing is required in your process, please specify the C-type heat-resistant coating grade, which maintains insulation performance after annealing at approximately 800°C.
Q3: What does B800 ≥ 1.87 T mean?
A: B800 is the magnetic flux density measured at 800 A/m magnetic field strength, which indicates how easily the material can be magnetized. A higher B800 means lower excitation current is needed at the same flux density - resulting in lower no-load current and better power factor.