1. Definition and Core Components

• Basic Composition: With iron (Fe) as the base, it adds 2.8% to 3.5% silicon (Si), along with trace amounts of carbon, aluminum, manganese, and other elements. The addition of silicon significantly increases the resistivity (reducing eddy current losses) while maintaining high magnetic permeability.

• Grain Orientation: Through cold rolling and annealing processes, a Goss texture ((110)[001] crystal orientation) is formed, concentrating the magnetization direction highly along the rolling direction, and the magnetic permeability can be 3 to 5 times higher than that of non-oriented steel.

2. Key Steps of Production Process

Hot rolling: Initial forming to a thickness of 2-3mm.

Cold rolling: Rolling at room temperature to the target thickness (0.18-0.35mm), with a compression ratio over 80%, and preliminary induction of grain orientation.

Annealing treatment:

• Primary annealing: Elimination of cold rolling stress.

•Secondary recrystallization annealing: At high temperatures (>1200°C), to align grains completely along the rolling direction, which is the core process.

Insulation Coating: Surface coating with phosphate or ceramic layers to reduce eddy currents between laminations and prevent corrosion.

3.Performance Advantages

•Low iron loss: Grain orientation reduces hysteresis loss, with typical iron loss values being over 50% lower than those of non-oriented steel.

•High magnetic saturation strength: Reaching 1.8 - 2.0T, it supports efficient energy transmission.

•Low magnetostriction: Reduces vibration noise by 30 - 50dB, suitable for quiet environments (such as transformers in residential areas).

•High stacking factor: >95%, allowing for compact design and saving material space.

4.Application Fields:

•Power transformers: The core accounts for 70% of the cost, and CRGO steel can improve efficiency to over 99%.

•Renewable energy equipment: Wind turbine generators, electric vehicle motors (high power density).

•Precision instruments: MRI equipment, high-precision sensors (reliant on magnetic field stability).

5.Future Development Trends

•Ultra-thin development: Advancing 0.10–0.18mm thickness for application in micro electronic transformers.

•Coating technology: Nano-insulating layers to further reduce eddy current losses.

•Green manufacturing: Scrap steel recycling rate >90%, reducing carbon footprint.

Silicon steel (electrical steel)

• Characteristics: Silicon steel is the most traditional core material. By adding silicon (typically 3% to 5%), the resistivity is increased to reduce eddy current losses while maintaining high magnetic permeability. Cold-rolled silicon steel sheets have grain orientation, which can further optimize the magnetic flux path.

• Advantages: Low cost, high mechanical strength, and mature manufacturing process, suitable for power frequency (50/60Hz) applications.

• Disadvantages: Iron losses significantly increase at high frequencies (hysteresis loss + eddy current loss), and efficiency is lower than that of new materials.

• Applications:

• Power transformers (distribution and transmission systems);

• Industrial transformers (medium and low-frequency equipment).

2. Amorphous Alloy (Amorphous Steel)

• Characteristics: Metal glass structure with disordered atomic arrangement (such as iron-boron-silicon alloy), isotropic magnetism, significantly reducing eddy current and hysteresis losses. Iron loss is 70% to 80% lower than that of silicon steel.

• Advantages: Ultra-high efficiency (extremely low no-load loss), environmentally friendly and energy-saving.

• Disadvantages: High mechanical brittleness, difficult processing, relatively low saturation magnetic flux density (about 1.5T), and cost is 1.5 to 2 times that of silicon steel.

• Applications:

• High-efficiency distribution transformers (especially in energy-saving scenarios);

• Renewable energy systems (photovoltaic inverters, wind power transformers).

 

3. Ferrite

•Characteristics: Ceramic material (MnZn/NiZn-based), high resistivity (>10^6 Ω·m), naturally suppresses eddy currents, but magnetic permeability varies significantly with temperature.

•Advantages: Excellent high-frequency performance (1kHz - 1MHz), small size, moderate cost.

•Disadvantages: Low saturation flux density (<0.5T), brittle, not suitable for high-power low-frequency applications.

• Applications:

• Switching power supplies (SMPS), RF transformers;

• Consumer electronics (chargers, TVs, communication devices).

4.Nanocrystalline Materials

• Characteristics: Nanoscale crystalline structure (iron-based alloys), combining high saturation flux density (over 1.2T) with low high-frequency losses and good temperature stability.

• Advantages: Comprehensive performance surpasses ferrite, high-frequency losses comparable to amorphous alloys.

• Disadvantages: High cost, complex mass-production processes.

• Applications:

• High-end high-frequency transformers (medical equipment, aerospace);

• Electric vehicle charging modules.

 

Other Materials

• Iron Powder Cores: Used in mid-frequency inductors, strong anti-saturation capability but higher losses.

• Permalloy (Nickel-Iron Based): Extremely high initial permeability, used in precision instruments, but with exceptionally high cost.