Grain-Oriented Silicon Steel (GOES Steel) is a high-end variety of electrical steel, also known as cold-rolled grain-oriented silicon steel. Electrical steel is an indispensable soft magnetic material in the power industry, mainly divided into two categories: grain-oriented silicon steel and non-oriented silicon steel. Through special rolling and heat treatment processes, grain-oriented silicon steel achieves a highly ordered arrangement of grains along the rolling direction (Goss texture), resulting in extremely low core loss and extremely high magnetic permeability in the rolling direction. It is an ideal core material for manufacturing stationary electromagnetic equipment such as transformers, reactors, and instrument transformers.
Electrical Steel (Non-oriented + Grain-oriented)
Electrical steel is the most widely used soft magnetic material in the power, electronics, and military industries, accounting for more than 90% of the global soft magnetic material consumption. According to grain orientation and silicon content, it is divided into two categories: grain-oriented and non-oriented.
| Category | Grain-Oriented Silicon Steel | Non-Oriented Silicon Steel |
| Grain orientation | Highly aligned (Goss texture) | Random uniform distribution |
| Silicon content | 3.0%–3.5% | 0.5%–4.5% |
| Typical thickness | 0.18–0.35 mm | 0.35–1.0 mm |
| Typical core loss P1.7/50 | 0.80–1.35 W/kg | Not applicable (usually measured at P1.5/50) |
| Typical core loss P1.5/50 | 0.45–0.90 W/kg | 1.5–6.0 W/kg |
| Maximum magnetic permeability | 50,000–100,000+ | 10,000–60,000 |
| Cost | High | Medium |
| Main applications | Transformers, reactors | Motors, generators, compressors |
The performance of electrical steel directly determines the energy efficiency level of power systems. China’s national standard GB 20052-2020 Minimum allowable values of energy efficiency and energy efficiency grades for power transformers mandates the use of high magnetic induction grain-oriented silicon steel (Hi-B steel) for manufacturing transformers of Grade 1 and Grade 2 energy efficiency.
International Standards
As a professional supplier of grain-oriented silicon steel, large steel enterprises provide products that comply with GB/T, IEC, ASTM, JIS, and other international standards, and support third-party inspections (SGS, BV, etc.).
- Base material standards: GB/T 2521.2-2016 (China), IEC 60404-8-7 (International), ASTM A876 (USA), JIS C 2553 (Japan).
- Core loss grades: For example, B23R080 indicates a thickness of 0.23 mm and core loss P1.7/50 ≤ 0.80 W/kg. ‘R’ stands for regular grade, ‘H’ for high magnetic induction (Hi-B).
- Insulating coating standards: GB/T 2522-2017, IEC 60404-11 (coating classes T1, T2, T3, T4).
- Energy efficiency certifications: Compliance with China Energy Label, EU EcoDesign Directive (EU 548/2014), US DOE energy efficiency standards.
Material Composition
The matrix of grain-oriented silicon steel is an iron-silicon alloy with a silicon content typically of 3.0%–3.5%, and small amounts of aluminum, manganese, nitrogen, copper, tin, and other elements are added to promote inhibitor formation and secondary recrystallization. The surface is coated with an insulating coating and a tension coating to reduce eddy current losses and improve magnetostriction properties.
- Matrix composition: Iron (Fe) balance, Silicon (Si) 3.0%–3.5%, Aluminum (Al) 0.01%–0.03%, Manganese (Mn) 0.05%–0.15%, Carbon (C) ≤0.005%, Sulfur (S) ≤0.003%, Nitrogen (N) ≤0.003%.
- Insulating coating: Phosphate-chromate based inorganic coating (withstands high-temperature stress relief annealing) + tension coating (reduces core loss and magnetostriction).
Specifications
Zhongxin Special Steel produces and sells grain-oriented silicon steel products with thickness ranging from 0.18 to 0.35 mm and width from 800 to 1050 mm, including grain-oriented silicon steel coils, sheets, slit strips, and laminated cores. Products are graded and supplied according to magnetic performance classes (e.g., B23R080, B27R090, B30R105, B35R135, etc.) and coating types (standard coating, high-tension coating, laser-scribed coating).
Material Properties of Grain-oriented Silicon Steel
Grain-oriented silicon steel features extremely low core loss, high magnetic permeability, low magnetostriction, etc. It is the most technologically advanced product among electrical steels. Its electromagnetic performance is far superior to that of non-oriented silicon steel and ordinary cold-rolled sheets.
- Ultra-low core loss (P1.7/50): Core loss as low as 0.80–1.35 W/kg (50 Hz, 1.7 T), significantly reducing no-load loss of transformers and meeting national Grade 1 energy efficiency standards.
- High magnetic permeability (μ): Maximum permeability up to 50,000–100,000+, low exciting current, high power factor.
- Low coercivity (Hc): Generally ≤10 A/m, extremely low hysteresis loss.
- Low magnetostriction: Laser scribing or mechanical scribing technology refines magnetic domains, reducing noise (≤55 dB for large-capacity transformers).
- High-tension coating: Inorganic coating provides tensile stress, further reducing core loss by 5%–10%.
- High-temperature stress relief annealing: Withstands stress relief annealing at 800–850°C without damaging insulation properties, facilitating magnetic performance recovery after core assembly.
- Environmental friendliness: Chromium-free coating trend, compliant with RoHS and REACH standards.
Applications of Grain-oriented Silicon Steel
Leveraging its core advantages of ultra-low loss, high permeability, and low noise, grain-oriented silicon steel is a key material for high-efficiency and energy-saving equipment in power transmission and distribution, renewable energy generation, rail transit, and other fields.
- Power transformers: Large oil-immersed transformers, dry-type transformers, amorphous alloy hybrid core transformers.
- Distribution transformers: Pole-mounted transformers, pad-mounted transformers, mining transformers.
- Reactors: Shunt reactors, current-limiting reactors, filter reactors.
- Instrument transformers: Voltage transformers, current transformers.
- Special transformers: Traction transformers for rail transit, rectifier transformers, medium-frequency furnace transformers.
- New energy vehicles: On-board charger transformers, DC-DC converter magnetic cores (high-frequency thin-gauge grain-oriented silicon steel).
Manufacturing Process of Grain-oriented Silicon Steel
The production process of grain-oriented silicon steel is extremely complex, often regarded as a “craftsmanship” product in the steel industry, with high technical barriers. The main process route is:
Steelmaking (ultra-low carbon/low sulfur) → Continuous casting (slab) → Hot rolling → Normalizing (primary recrystallization) → Cold rolling (single or two-stage cold rolling with intermediate annealing) → Decarburization annealing + primary recrystallization → High-temperature annealing (secondary recrystallization, 1200°C) → Insulating coating + hot-stretching flattening → Laser scribing (optional) → Finishing → Inspection and packaging.
- Steelmaking and continuous casting: Vacuum degassing (RH), ladle refining (LF), control of inclusions, addition of inhibitor elements (AlN, MnS, Cu, etc.).
- Hot rolling: Reheat slab to 1300–1400°C (to dissolve inhibitors), then rough and finish rolling.
- Normalizing annealing: Adjust microstructure, precipitate fine inhibitor particles.
- Cold rolling: Single-stage cold rolling to 0.18–0.35 mm with reduction ≥80%, forming Goss texture precursor.
- Decarburization annealing: Remove carbon to below 0.003%, while primary recrystallization occurs.
- High-temperature bell annealing: Long-term annealing at 1200°C in pure H₂ atmosphere, causing secondary recrystallization with highly aligned grain orientation.
- Insulating coating + tension coating: Apply inorganic insulating layer and bake to cure, while applying tensile stress.
- Laser scribing: Laser scan on the surface to refine magnetic domains, reducing core loss by approximately 5–8%.
- Finishing and shearing: Slitting, edge trimming, punching (note: grain-oriented silicon steel is brittle and usually not subjected to complex punching).
Grain-oriented Silicon Steel Suppliers
Purchasing directly from a grain-oriented silicon steel manufacturer ensures consistent magnetic performance, uniform coating, and stable delivery schedules.
Factory Inspection Focus
Steel cleanliness: Availability of RH vacuum degassing, continuous casting electromagnetic stirring to ensure T[O] ≤ 15 ppm, S ≤ 0.003%.
- Hot rolling high-temperature heating: Slab reheating furnace temperature ≥1350°C to ensure full dissolution of inhibitors.
- Cold rolling precision: Thickness tolerance within ±0.005 mm, good shape.
- High-temperature bell furnace: 1200°C pure H₂ annealing, dew point ≤ -40°C, temperature uniformity ±3°C.
- Laser scribing equipment: Adjustable scribing depth and spacing to effectively reduce core loss.
- Magnetic testing system: Epstein frame or single sheet tester, supporting full-point testing at 1.7 T/50 Hz.
Zhongxin Special Steel Factory
- Certifications: ISO 9001, IATF 16949, GB/T 2521.2, IEC 60404, CNAS laboratory accreditation.
- Capacity: 300,000 tons/year of grain-oriented silicon steel (including 100,000 tons/year of Hi-B steel).
- Lead time: 30–90 days (customized by grade and coating).
- Production lines: 2 medium/thick slab continuous casters, 1 normalizing and pickling line, 2 Z-mill 20-high cold rolling mills, 4 high-temperature bell annealing furnaces (single furnace capacity 80 tons), 2 hot-stretching flattening and coating lines, 2 laser scribing lines.
Customization of Grain-oriented Silicon Steel Products
We offer complete customization solutions for grain-oriented silicon steel, providing one-stop services based on transformer design, core manufacturing processes, and cost requirements.
Specification Selection
- Thickness specifications: 0.18 mm / 0.23 mm / 0.27 mm / 0.30 mm / 0.35 mm (tolerance ±0.005 mm).
- Conventional grain-oriented silicon steel (CGO): e.g., 27QG100, 30QG120, 35QG135.
- High magnetic induction grain-oriented silicon steel (Hi-B): e.g., 23RK085, 27RK090, 30RK105, 35RK125.
Coating Types
- T1 (phosphate-chromate, withstands high-temperature stress relief annealing)
- T2 (high-tension coating, reduces core loss)
- T3 (T2 + laser scribing, suitable for low-noise transformers)
- T4 (extremely low magnetostriction coating)
Finished Forms
- Mother coils / slit narrow strips
- Cut-to-size sheets (e.g., for step-lap joints)
- Sheared laminations (for step-cut core assembly)
- Wound cores (toroidal, rectangular)
- Stacked laminations (customizable air gaps, clamping parts)
Grain-oriented silicon steel, as the “crown jewel” of electrical steels, with its extremely low core loss, ultra-high magnetic permeability, and mature tension coating + laser scribing technology, has become the core material for high-efficiency, energy-saving, low-noise transformers worldwide. If you are looking for compliant materials or low-loss magnetic cores for new energy and rail transit applications, then Zhongxin Special Steel‘s grain-oriented silicon steel is your most suitable choice!
