Properties, Standards, and Grade Cross-Reference of Chinese Silicon Steel Sheets

Silicon steel sheet, also known as electrical steel, is a silicon-iron soft magnetic alloy with extremely low carbon content. Typically containing 0.5% to 4.5% silicon, this material is engineered to increase electrical resistivity and magnetic permeability while minimizing coercivity, core loss (iron loss), and magnetic aging.

Electrical steel serves as the primary magnetic core material for power transformers, distribution transformers, electric motors, and generators. Choosing the right silicon steel grade directly determines the energy efficiency, operating temperature, and overall performance of electrical equipment.

Key Performance Indexes of Silicon Steel Sheets

1. Low Core Loss (Iron Loss)

Core loss is the most critical quality index of electrical steel. Measured in W/kg under specified magnetic flux densities and frequencies (typically 50Hz or 60Hz), lower iron loss signifies higher energy efficiency. In transformer and motor design, higher grades deliver significantly reduced heat generation and lower no-load loss.

2. High Magnetic Induction (Permeability)

High magnetic induction allows the steel core to establish stronger magnetic flux with smaller magnetizing currents. Equipment constructed with high-permeability silicon steel achieves higher operational efficiency, reduced copper wire consumption, and smaller overall physical dimensions.

3. Surface Flatness and Uniform Thickness

To maximize the core stacking factor (lamination density), the surface of silicon steel sheets must be smooth, flat, and uniform in thickness. Consistent thickness prevents local overheating and vibration noise within the transformer or motor stack.

4. Insulation Coating, Adhesion, and Weldability

High-quality electrical steel features an inorganic or semi-organic insulation coating. Excellent coating adhesion prevents corrosion, reduces eddy current losses between laminations, prolongs tool life during punching, and ensures good weldability during core fabrication.

Impact of Processing Technology on Core Efficiency

The performance of a finished transformer depends not only on the raw material grade, but also on the precision of core processing techniques:

• Stamping and Shear Burrs: Large punching burrs disrupt insulation between laminations, causing localized eddy currents. Differences in burr quality can alter total transformer efficiency by up to 7%.

• Stress-Relief Annealing: Cold working and stamping introduce mechanical stress into the magnetic domain structure. Applying nitrogen-protected stress-relief annealing after stamping restores magnetic properties, reducing core loss by 7% to 10% compared to non-annealed cores.

Silicon Steel Grade Cross-Reference Table

China's current national standards (such as GB/T 2521) adopt modern designations based on sheet thickness, steel type, and maximum core loss limits. The table below outlines the cross-reference between classic Chinese designations, current national standards, and major global steel producers (Baosteel, Nippon Steel, JFE, TISCO).

Cold-Rolled Non-Oriented Silicon Steel (CRNGO)

Cold-Rolled Grain-Oriented Silicon Steel (CRGO)

Silicon Steel Selection Guide for Transformers and Motors

1. CRGO vs. CRNGO Applications

• Grain-Oriented Silicon Steel (CRGO): Demonstrates superior magnetic properties along the rolling direction. It is the mandatory choice for static induction apparatus like power transformers, distribution transformers, and reactors.

• Non-Oriented Silicon Steel (CRNGO): Features uniform magnetic properties in all directions. It is ideal for rotating electrical machinery, including electric motors, generators, and micro-motors.

2. Thickness and Frequency Considerations

• Higher operating frequencies generate significantly greater eddy current losses. For high-frequency applications, select thinner sheets (e.g., 0.23mm, 0.27mm, or 0.30mm) to maintain low core losses.

• Standard 50Hz/60Hz distribution transformers generally employ 0.27mm to 0.35mm CRGO steel sheets to balance thermal performance and raw material cost.

3. Temperature Rise and No-Load Performance

• Higher grades (such as H12 or H14) yield lower core temperature rises during continuous operation compared to lower grades (such as H23 or H50).

• Selecting fully processed, nitrogen-annealed black sheet options enhances magnetic domain recovery, delivering superior no-load current control compared to non-annealed white sheets.

Consult Hengfengyou Electric for Core Materials and Technical Specs

Choosing the optimal silicon steel grade is critical to meeting international efficiency standards (such as IEC, IEEE, and GB requirements) while maintaining competitive manufacturing costs.

As a professional manufacturer of transformers, switchgear, and electrical components, Hengfengyou Electric Co., Ltd. provides high-grade processed silicon steel sheets, slit coils, and custom cut-to-length transformer cores tailored to your exact engineering specifications.

Get in Touch with Our Engineering & Sales Team:

• Request updated technical datasheets and mill test certificates (MTC).

• Receive customized core loss evaluations and material selection advice.

• Get real-time competitive quotations for CRGO and CRNGO silicon steel materials.

[Contact Hengfengyou Electric for a Real-Time Quote & Technical Support]