Choosing between CRGO and CRNGO electrical steel is one of the most consequential material decisions in transformer and motor design — and the wrong choice can increase core loss by 3 to 6 times. This guide breaks down every meaningful difference between Cold-Rolled Grain-Oriented (CRGO) steel and Cold-Rolled Non-Grain-Oriented (CRNGO) steel, so you can select the right grade with confidence.
Core Key Points
- CRGO has grains aligned in the rolling direction, giving it extremely low core loss (P₁.₇/₅₀ ≈ 0.85–1.10 W/kg) — ideal for static equipment like power transformers.
- CRNGO has randomly oriented grains, offering isotropic magnetic properties in all directions — the right choice for rotating machinery like motors and generators.
- CRGO silicon content is approximately 3.0–3.5%; CRNGO ranges from 0.5–3.0%.
- CRGO carries a processing premium of 250–350% above CRNGO pricing due to secondary recrystallization manufacturing complexity.
- Mixing CRGO in a motor core or CRNGO in a large power transformer core both result in significant efficiency losses — application fit is non-negotiable.
What Is CRGO Steel?
Cold-Rolled Grain-Oriented (CRGO) electrical steel is a silicon-alloyed flat-rolled steel in which the crystallographic grain structure is aligned predominantly in the rolling direction through a carefully controlled secondary recrystallization process (the Goss texture). This alignment means the material exhibits exceptionally high magnetic permeability and extremely low core loss specifically along the rolling direction.
Zhongxin Steel supplies CRGO in conventional grades (0.23–0.35 mm thickness) and ultra-thin grades (0.10–0.20 mm), covering standard grades such as B23G110, B27G120, and B30G120 per IEC, JIS, and ASTM standards.
Key manufacturing steps unique to CRGO:
- Multiple cold-rolling passes with intermediate annealing
- Decarburization annealing to reduce carbon below 30 ppm
- Secondary recrystallization (high-temperature annealing at ~1,200°C) to develop Goss texture
- Magnesium oxide coating (glass film) for insulation and surface quality
- Stress-relief annealing after cutting for core builders
What Is CRNGO Steel?
Cold-Rolled Non-Grain-Oriented (CRNGO) electrical steel — also written as CRNGO or NGO — is silicon-alloyed sheet steel in which the grain structure is essentially random, with no preferred crystallographic orientation. The result is a material with nearly equal magnetic performance in all directions within the plane of the sheet.
CRNGO typically contains 0.5–3.0% silicon and is available in thicknesses from 0.35 mm to 0.65 mm (standard grades) and as thin as 0.05–0.20 mm (ultra-thin for high-frequency motor applications). Grades range from semi-processed (requires final annealing by the stamper) to fully-processed (ready to punch and stack).
Side-by-Side Comparison
| Property | CRGO | CRNGO |
|---|---|---|
| Grain structure | Aligned (Goss texture) | Random / isotropic |
| Silicon content | 3.0–3.5% | 0.5–3.0% |
| Core loss P₁.₇/₅₀ | 0.85–1.10 W/kg | 2.5–6.0 W/kg |
| Magnetic induction B₈ / B₅₀ | ≥ 1.88 T (B₈) | 1.65–1.75 T (B₅₀) |
| Directionality | Highly anisotropic | Isotropic |
| Typical thickness | 0.10–0.35 mm | 0.05–0.65 mm |
| Processing complexity | High (secondary recrystallization) | Moderate |
| Relative cost | High (250–350% premium over CRNGO) | Moderate |
| Primary application | Power & distribution transformers | Motors, generators, alternators |
| IEC standard | IEC 60404-8-7 | IEC 60404-8-4 |
Data compiled from IEC 60404 series and Zhongxin Steel product testing. Core loss values at 1.7 T, 50 Hz (CRGO) and 1.5 T, 50 Hz (CRNGO).
Magnetic Properties Deep Dive
Why Grain Orientation Changes Everything
The secondary recrystallization process produces a near-perfect Goss texture ({110}<001> orientation) in CRGO steel. When the magnetic flux travels along the rolling direction, it encounters minimal energy loss because the easy magnetization axis aligns with the flux path. Core loss as low as 0.85 W/kg at 1.7 T, 50 Hz is achievable in high-permeability (Hi-B) CRGO grades.
Rotate that same CRGO sheet 90° — flux now travels across the grain — and core loss can increase by 3 to 5 times, reaching 4–5 W/kg. This is why transformer core builders must cut and stack CRGO laminations with precise directional control.
CRNGO’s Isotropy Advantage
CRNGO’s random grain structure means core loss varies only slightly with flux direction — typically within ±15% between the rolling direction and transverse direction. For a rotating machine where the magnetic flux sweeps through all angles of the stator lamination during each electrical cycle, this isotropy is essential. A CRGO stator would lose the efficiency advantage entirely, because much of the flux would travel across the high-loss transverse direction.
According to the International Energy Agency (IEA) World Energy Outlook 2025, electric motors account for approximately 45% of global electricity consumption, making even a 1% improvement in CRNGO motor steel efficiency enormously impactful at scale.
Frequency Considerations
At higher frequencies (400 Hz–20 kHz), eddy-current losses dominate. Ultra-thin CRNGO (0.05–0.20 mm) is specified for high-speed EV traction motors operating at 800 Hz–2,000 Hz, while ultra-thin CRGO (0.10–0.20 mm) addresses high-frequency distribution transformers and special-purpose inductors.
Application Fit Matrix
| Application | Recommended Grade | Why |
|---|---|---|
| Large power transformer (≥ 10 MVA) | CRGO (0.27–0.30 mm) | Directional flux path; low core loss critical |
| Distribution transformer (< 1 MVA) | CRGO (0.30–0.35 mm) | Same directional flux; lower-grade CRGO acceptable |
| High-efficiency induction motor (IE3/IE4) | CRNGO (0.35–0.50 mm) | Isotropic; rotating flux requirement |
| EV traction motor (400 Hz+) | Ultra-thin CRNGO (0.10–0.20 mm) | High frequency; rotating flux |
| High-frequency power transformer | Ultra-thin CRGO (0.10–0.18 mm) | Low eddy loss; directional flux |
| Small ballast / reactor | CRNGO (0.50–0.65 mm) | Low cost; multi-directional flux |
| Generator / alternator stator | CRNGO (0.35–0.50 mm) | Rotating flux; isotropic property needed |
Cost and Processing Considerations
CRGO steel commands a significant cost premium. The processing premium for CRGO typically ranges $300–$500 per tonne above standard cold-rolled steel, compared to $80–$150 per tonne for CRNGO, according to BusinessAnalytiq’s Grain-Oriented Electrical Steel Price Index 2026. This reflects:
- Longer production cycle — CRGO requires 5–7 cold-rolling and annealing cycles vs. 2–3 for CRNGO.
- Higher silicon content — Silicon additions alone add approximately $150–200 per tonne.
- Tighter quality control — CRGO must achieve ≥ 95% Goss-textured grains; rejections are higher.
- Narrower supply base — Major CRGO producers include Baosteel, NLMK, Nippon Steel, and JFE, creating a more concentrated supply chain.
For transformer builders, however, the CRGO premium is typically offset by reduced operating losses over the transformer’s 25–40 year service life. A distribution transformer running at 70% load for 30 years can recover the incremental CRGO material cost within 3–5 years through electricity savings alone.
How to Choose: Decision Framework
Ask these three questions before specifying your electrical steel grade:
1. Is the magnetic flux path directional or rotating?
- Directional (transformer, reactor, inductor) → CRGO
- Rotating (motor, generator, alternator) → CRNGO
2. What operating frequency?
- 50/60 Hz → Standard thickness (0.27–0.50 mm)
- 200–2,000 Hz → Ultra-thin (0.05–0.20 mm)
3. What efficiency class or loss budget applies?
- Strict loss budget (e.g., IEC 60076 AA0/A0 transformer class) → High-permeability CRGO (Hi-B)
- Standard loss budget → Conventional CRGO or fully-processed CRNGO
When in doubt, contact Zhongxin Steel’s technical team for a free grade selection consultation with sample testing.
FAQ
What does CRGO stand for?
CRGO stands for Cold-Rolled Grain-Oriented electrical steel. The “grain-oriented” refers to the alignment of the steel’s crystalline grain structure along the rolling direction through a secondary recrystallization process, which gives the material exceptionally low core loss in that specific direction.
Can I use CRNGO in a transformer to save cost?
Using CRNGO in a power or distribution transformer is strongly discouraged. Because the transformer core carries directional flux, CRNGO’s higher core loss (2.5–6.0 W/kg vs. 0.85–1.10 W/kg for CRGO) results in significantly higher no-load losses over the transformer’s lifetime. The initial material cost saving is outweighed many times over by increased energy waste.
What is the core loss difference between CRGO and CRNGO?
At 1.7 T, 50 Hz, CRGO core loss ranges from 0.85 W/kg (Hi-B grades) to 1.10 W/kg (standard grades). CRNGO at 1.5 T, 50 Hz typically ranges from 2.5 W/kg (low-loss fully-processed grades) to 6.0 W/kg (semi-processed economy grades). The difference is approximately 3–6× in favor of CRGO for transformer applications.
Is CRGO or CRNGO better for EV motors?
CRNGO — specifically ultra-thin CRNGO in the 0.10–0.20 mm range — is the correct choice for EV traction motors. EV motors generate rotating magnetic flux, requiring isotropic magnetic properties that only CRNGO provides. Ultra-thin gauges reduce eddy-current losses at the high operating frequencies (800–2,000 Hz) typical of modern EV drivetrains.
What thickness of CRGO is used in standard distribution transformers?
Most distribution transformers (up to 2.5 MVA) use CRGO in 0.27 mm or 0.30 mm thickness. Larger power transformers may use 0.23 mm Hi-B grade for maximum efficiency. The thinner the lamination, the lower the eddy-current loss component — but thinner laminations also increase manufacturing complexity and cost.
References
- IEC 60404-8-7:2023 — Magnetic materials — Part 8-7: Specifications for individual materials — Cold-rolled grain-oriented electrical steel strip and sheet delivered in the fully-processed state. Geneva: International Electrotechnical Commission.
- IEC 60404-8-4:2022 — Magnetic materials — Part 8-4: Specifications for individual materials — Cold-rolled non-oriented electrical steel strip and sheet delivered in the fully-processed state. Geneva: International Electrotechnical Commission.
- BusinessAnalytiq (2026). Grain-Oriented Electrical Steel Price Index. Retrieved from https://businessanalytiq.com/procurementanalytics/index/grain-oriented-electrical-steel-price-index/
- International Energy Agency (2025). World Energy Outlook 2025 — Energy Efficiency. Paris: IEA. https://www.iea.org/reports/world-energy-outlook-2025
- Verifiedmarketresearch.com (2026). Cold Rolled Grain-Oriented Silicon Steel Market Size & Forecast. Retrieved from https://www.verifiedmarketresearch.com/product/cold-rolled-grain-oriented-silicon-steel-market/
For grade datasheets, mill test certificates, and custom slitting specifications, visit Zhongxin Steel Products or contact us at sales@wuxisteel.cn.
Related reading: Grain Oriented Silicon Steel Product Page · Non-Oriented Silicon Steel Product Page · Ultra-Thin Silicon Steel