What Is Electrical Steel (Silicon Steel)? Definition, Grades, Uses & Market 2026
Jay Zheng
Sep 26, 2024
Quick answer: Electrical steel — also called silicon steel — is an Fe-Si soft-magnetic alloy containing 0.4%–6.5% silicon. It comes in two families: grain-oriented (GO) grades such as 27Q120, B23P085 and B20R070–B30R090, built for transformer cores where the magnetic field flows in one direction; and non-oriented (NGO) grades such as 50WW470, B50A800 and M19 (35WW300), built for motors and generators where the field rotates. The global market was worth about USD 19 billion in 2024 and is projected to reach USD 29.7 billion by 2032 (CAGR ≈ 5.0%), driven by grid investment, electric vehicles and renewable energy.
What is electrical steel (silicon steel)?
Electrical steel refers to the Fe-Si soft magnetic alloy, also known as silicon steel or lamination steel. The mass percentage of silicon ranges from 0.4% to 6.5%. It is characterized by high magnetic permeability and low core loss, together with good punching quality, high-quality surface and an effective insulating coating. Electrical steel is used to manufacture the cores of motors, generators and transformers — it is an indispensable functional material for the power, electronics and defence industries, and the key material for improving efficiency and cutting energy consumption of electrical equipment. As the highest-volume soft magnetic alloy, it is used in every sector of the real economy.
Why it matters: electromagnetic conversion
Electromagnetic induction is the phenomenon in which an electromotive force (EMF) is generated in a conductor when it moves through a magnetic field or when the magnetic field changes. According to Faraday's law, when a conductor cuts magnetic flux lines, an EMF appears at its ends and drives current in a closed circuit. Conversely, current passing through a conductor in a magnetic field produces a force that moves the conductor — converting electrical energy into mechanical energy. This principle powers generators, motors and transformers.
Electrical steel is the material that makes this conversion efficient. Its value comes from four effects:
- Reducing core loss: low hysteresis and eddy-current losses cut the energy consumed inside the core itself, directly improving the efficiency of motors and transformers.
- Enhancing magnetic permeability: high permeability makes the material easy to magnetize and conduct magnetic flux, so strong magnetic fields can be established with small magnetizing currents.
- Suppressing eddy currents: thin laminations with an insulating coating break up eddy currents, the circulating currents inside a conductive core that dissipate energy as heat.
- Shaping the magnetic circuit: stacked laminations form a low-reluctance path that guides flux precisely through the air gap and windings, reducing stray losses.
Grain-oriented (GO) vs non-oriented (NGO): the two families
Every electrical steel grade belongs to one of two families, and they are not interchangeable. Grain-oriented steel is processed so that its crystals align with the rolling direction, giving exceptional permeability and very low loss — but only along that direction. Non-oriented steel has a random crystal texture with nearly uniform properties in every direction.
| Property | Grain-oriented (GO) | Non-oriented (NGO) |
|---|---|---|
| Crystal texture | Strong Goss texture, grains aligned to rolling direction | Random texture, magnetically uniform |
| Best direction | Rolling direction only (strongly anisotropic) | All in-plane directions (near isotropic) |
| Core-loss test condition | 1.7 T / 50 Hz (P1.7/50) | 1.5 T / 50 Hz (P1.5/50) |
| Magnetization guarantee | J800 / B800 (800 A/m) | J5000 / B50 (5,000 A/m) |
| Typical thickness | 0.18–0.35 mm | 0.35–0.65 mm |
| Typical grades | 27Q120, B23P085, B20R070 / B23R080 / B30R090 | 50WW470, B50A800, M19 (35WW300) |
| Main applications | Power & distribution transformers, reactors | Motors, generators, compressors, small transformers |
Oriented electrical steel (GO)
- Material characteristics: highly anisotropic — permeability is extremely high and hysteresis loss extremely low in the grain orientation direction.
- Manufacturing: grain structure is deliberately developed so crystals align in the sheet plane, giving the best magnetic properties in one specific direction.
- Applications: high-efficiency, high-permeability cores such as power and distribution transformers and reactors, where flux flows in a closed, essentially unidirectional loop.
Non-oriented electrical steel (NGO)
- Material characteristics: no significant anisotropy — magnetic properties are relatively uniform in all directions, with average permeability and hysteresis loss in every direction.
- Manufacturing: grains are not deliberately oriented, so properties stay consistent in all directions of the sheet.
- Applications: rotating machines — motors and generators — plus small transformers and appliance cores, where the magnetic field rotates or changes direction constantly.
In short: GO steel serves unidirectional magnetic circuits (transformers); NGO steel serves rotating or multidirectional fields (motors and generators).
A brief history
Before silicon steel existed, cores were made from industrial pure iron or low-carbon steel — with high core loss and severe magnetic aging. In 1902 the German researcher Gumlich discovered that adding silicon raises resistivity, cuts eddy-current and hysteresis losses and improves permeability. Hot-rolled silicon steel dominated from 1903 until the 1960s, when cold-rolled products replaced it. Cold-rolled grain-oriented (CGO) steel was industrialized from 1933 via the Armco process; high-permeability Hi-B grades followed from 1961–1968, led by Nippon Steel of Japan. China trial-produced hot-rolled low-silicon plate in 1952, developed 3% Si cold-rolled GO steel in 1957, and began industrial GO production at Wuhan Steel in 1979 after introducing Nippon Steel technology — today Baosteel and Shougang are world leaders in the field.
How electrical steel is classified
By silicon content
By silicon mass fraction, the industry distinguishes low-silicon electrical steel (below 0.5% Si) used where electromagnetic demands are modest; the mainstream 0.5%–4.5% Si electrical steels that cover most motor and transformer applications; and high-silicon alloys of 4.5%–6.7% Si, which show much lower loss at high frequency and are used for high-frequency motors, transformers and chokes. The 6.5% Si grade is a category of its own — outstanding magnetic properties but very poor room-temperature plasticity, so it cannot be conventionally rolled and is only available in limited quantities.
By production process
Hot-rolled electrical steel has been phased out because of its inferior magnetic performance. Modern production is cold-rolled: cold-rolled non-oriented steel (0.5%–4.0% Si+Al, rolled to 0.65 / 0.50 / 0.35 mm, then annealed and coated) serves motor and generator laminations; cold-rolled grain-oriented steel delivers high permeability and low loss along the rolling direction for power transformers, chokes and other high-end magnetic components.
Key performance indicators
Two indicators decide the grade of electrical steel, because they directly set the efficiency, size and cost of the finished machine:
- Core loss (iron loss, W/kg): the energy dissipated in the core per kilogram at a defined induction and frequency. NGO grades are rated at 1.5 T / 50 Hz (P1.5/50) and GO grades at 1.7 T / 50 Hz (P1.7/50). The loss class is often encoded in the grade number itself — 470 in 50WW470 means a nominal 4.70 W/kg, and 120 in 27Q120 means 1.20 W/kg.
- Magnetic induction (flux density, T): the guaranteed magnetization at a defined field strength — B50 (at 5,000 A/m) for NGO steel and B8 (at 800 A/m) for GO steel. Higher induction allows a smaller core cross-section, less copper winding and lower total cost, so high-permeability grades (Hi-B, such as B23R080) carry a premium.
Roundness of these values depends on composition design, rolling precision and coating quality. For NGO steel, anisotropy is also controlled: the difference in iron loss between the rolling and transverse directions should be ≤ 8%, and in magnetic induction ≤ 10%.
Electrical steel grades and standards
Grade designations encode thickness, product family and loss class. In Chinese NGO grade 50WW470: 50 = 0.50 mm nominal thickness, WW = conventional non-oriented, 470 = 4.70 W/kg nominal loss at 1.5 T / 50 Hz. In GO grade 27Q120: 27 = 0.27 mm, Q = grain-oriented (取向), 120 = 1.20 W/kg at 1.7 T / 50 Hz; suffixes refine the family — P/R for high permeability (Hi-B) and RD for laser domain-refined grades for distribution transformers. Chinese mills certify to enterprise standards Q/BQB 480 (NGO) and Q/BQB 485 (GO) with GB/T 2521 as the national standard, while overseas buyers usually reference EN 10106, JIS C 2552 or AISI loss classes. The full cross-reference tables — including how 50WW470 maps to M470-50A, 50A470 and AISI M27 — are in our electrical steel grade equivalents guide. Typical mill grades we supply are listed on the B20R070–B30R090 grain-oriented page and the B50A800 non-oriented page.
Applications: where electrical steel is used
| Sector | Steel family | Why this family |
|---|---|---|
| Power transformers (transmission grid) | GO (Hi-B, e.g. B23R080) | Lowest core loss where flux is unidirectional; efficiency standards keep tightening |
| Distribution transformers | GO incl. domain-refined RD grades | EU Ecodesign and DOE efficiency rules push utilities toward low-loss cores |
| EV and hybrid drive motors | High-grade NGO (35WW300 / M19 class) | High efficiency at high rotational speed; Baosteel supplies over 50% of China's EV drive-motor silicon steel |
| Wind and solar (generators, inverter transformers) | Both GO and NGO | Renewable build-out is the fastest-growing demand driver |
| Industrial motors, compressors, pumps, appliances | NGO (50WW470–50WW800 class) | Cost-effective laminations with uniform magnetic properties |
Global market and manufacturers
The global electrical steel market was valued at USD 18.95 billion in 2024 and is projected to grow from USD 20.14 billion in 2025 to USD 29.65 billion by 2032, a compound annual growth rate of about 5.0% (Fortune Business Insights). Grid investment, transformer replacement, EV production and renewable energy are the main growth engines.
China is the largest producer and exporter. In the first half of 2023 China produced 7.25 million tonnes of electrical steel — 1.23 Mt of grain-oriented steel (+16.98% year on year) and 6.02 Mt of non-oriented steel (+7.23%). China exported roughly 1.23 million tonnes in 2023, with India, Turkey, Mexico, Italy and the United States as the top five buyers. Globally, the leading producers are Baosteel and Shougang in China, Nippon Steel and JFE in Japan, POSCO in Korea, and a fast-growing group of Indian producers including JSW and Tata Steel. Within China, Baosteel held about 53% of the GO market and 28% of the NGO market (2020 data), and its silicon steel runs in more than half of China's electric-vehicle drive motors.
The future of electrical steel
Over the past two decades China's electrical steel industry — led by Baosteel, Shougang and WISCO — has closed most of the gap with Japan, but Japanese mills still lead in ultra-low-loss Hi-B down to 0.15 mm and in 6.5% Si strip made by CVD silicon infiltration (JFE). The industry's roadmap is clear: lower core loss and higher induction; thinner gauges; EV-grade non-oriented steel with better punchability; 6.5% Si alloys for high-frequency applications; and greener production. Competition between China, Japan and Korea will intensify exactly in these high-end segments — which is where grade selection and a reliable supplier matter most.
Sourcing electrical steel from China
Baohui Steel is a Shanghai-based steel exporter and Baosteel channel partner. We stock and mill-order both grain-oriented and non-oriented electrical steel — from workhorse grades like 27Q120, B23P085 and 50WW470 to high-permeability B20R070–B30R090 — with mill test certificates, seaworthy packing and export documentation handled end to end. Browse our electrical steel (silicon steel) supply page for available grades and indicative FOB pricing, and read how to import steel from China for the full process from quotation to bill of lading.
