Electrical Steel: Properties, Uses & How It Powers Electric Devices

If you’ve ever used a fridge, turned on a fan, or relied on solar panels, you’ve benefited from Electrical Steel. Also called silicon steel, this specialized material is designed to handle magnetic fields efficiently—making it the backbone of transformers, electric motors, and generators. Unlike regular steel, it minimizes energy loss (called “core loss”) when exposed to magnets, which is critical for making electrical devices efficient. In this guide, we’ll break down its key properties, real-world uses, how it’s made, and how it compares to other materials. Whether you’re an engineer, manufacturer, or energy professional, this guide will help you understand why electrical steel is essential for modern electricity.

1. Material Properties of Electrical Steel

Electrical Steel’s superpower lies in its magnetic performance. Its properties are tailored to maximize magnetic permeability (how well it conducts magnetic fields) and minimize core loss (energy wasted as heat). Let’s dive into its traits.

Chemical Composition

The key element here is silicon—without it, regular steel would be too lossy for electrical use. Typical composition includes:

• Carbon (C): ≤0.005% – Extremely low carbon to reduce magnetic hysteresis (a major cause of core loss).
• Silicon (Si): 1.0 – 4.5% – The “magic ingredient”; silicon increases electrical resistivity (slows eddy currents, which cause heat loss) and improves magnetic permeability.
• Manganese (Mn): 0.15 – 0.50% – Enhances workability (helps the steel be rolled into thin sheets) and reduces brittleness from high silicon.
• Phosphorus (P): ≤0.03% – Minimized to avoid increasing core loss and brittleness.
• Sulfur (S): ≤0.01% – Kept very low to prevent the formation of small particles that disrupt magnetic performance.
• Trace Elements: Small amounts of Aluminum (Al) (0.10 – 0.50%, boosts resistivity), Chromium (Cr) (≤0.10%, improves corrosion resistance), or Nickel (Ni) (≤0.10%, refines magnetic properties) – added in tiny doses to fine-tune performance.
• Molybdenum (Mo), Vanadium (V), Tungsten (W): Rarely used (≤0.05% each) – only in high-performance grades for specialized motors.

Physical Properties

These traits are critical for magnetic and thermal performance:

Mechanical Properties

Electrical Steel is softer than regular steel—trade-off for better magnetic performance:

• Hardness: 80 – 130 HB (Brinell) – Soft enough to be rolled into thin sheets (0.10 – 0.50 mm thick) without cracking.
• Tensile Strength: 300 – 500 MPa – Weaker than regular steel but strong enough for its uses (e.g., supporting transformer cores).
• Yield Strength: 200 – 350 MPa – Bends slightly under stress (e.g., during motor assembly) but returns to shape.
• Elongation: 10 – 25% – Stretches enough to be formed into complex shapes (e.g., curved motor cores) without breaking.
• Impact Toughness: 20 – 50 J/cm² – Moderate (softer grades are more brittle) – not designed for high-impact use, just magnetic performance.
• Fatigue Resistance: Good – Withstands repeated magnetic cycles (e.g., a motor running 24/7) without degrading.

Other Properties

These are the traits that make electrical steel unique for electrical devices:

• Magnetic Anisotropy: Directional magnetic properties – grain-oriented electrical steel (GOES) has better permeability along one direction (ideal for transformers), while non-oriented (NOES) is uniform (good for motors).
• Core Loss: 0.10 – 2.0 W/kg (at 50/60 Hz) – Much lower than regular steel (10+ W/kg) – saves energy (e.g., a transformer with low core loss uses 10–20% less electricity).
• Saturation Induction: 1.5 – 2.0 T (tesla) – High enough to generate strong magnetic fields (critical for powerful motors or generators).
• Edge Quality: Smooth, burr-free edges – Prevents eddy currents from concentrating at rough edges (which increases core loss).
• Surface Finish: Thin insulation layer (0.5 – 2 μm) – Coated on sheets to prevent electrical shorting between layers (e.g., in transformer cores stacked from thin sheets).

2. Applications of Electrical Steel

Every device that uses magnets or electricity relies on electrical steel. Here are its top uses:

Transformers

Transformers (which step up/down electricity for power grids or electronics) use electrical steel for their cores:

• Power Transformers (grid-scale): Use grain-oriented electrical steel (GOES) – its directional permeability reduces core loss, saving energy in power distribution.
• Small Transformers (phone chargers, TVs): Use non-oriented electrical steel (NOES) – cheaper and easier to shape into small cores.

Electric Motors

Motors (in cars, appliances, factories) depend on it to generate torque:

• Household Appliance Motors: Fridges, washing machines, fans – Use NOES (uniform permeability works for rotating magnetic fields).
• Electric Vehicle (EV) Motors: High-performance NOES or low-loss GOES – Reduces core loss to extend EV battery life (every 1% lower core loss = 2–3% longer range).
• Industrial Motors: Large factory motors – Use thick-gauge NOES (0.35–0.50 mm) for durability and efficiency.

Generators

Generators (solar, wind, hydro) use electrical steel to convert motion into electricity:

• Wind Turbine Generators: Use low-loss GOES – Handles high magnetic fields and reduces energy waste (critical for maximizing wind energy output).
• Solar Inverter Transformers: Use small NOES cores – Efficiently converts DC solar power to AC grid power.

Electrical Appliances

Even small devices use electrical steel:

• Microwave Transformers: Use GOES to generate high voltage for cooking.
• Vacuum Cleaner Motors: Use tiny NOES cores – Powers the fan while minimizing heat.

Power Distribution Equipment

Grid infrastructure relies on it:

• Switchgear: Uses electrical steel cores in current transformers (to measure electricity flow safely).
• Voltage Regulators: Use GOES to stabilize grid voltage, reducing energy waste.

3. Manufacturing Techniques for Electrical Steel

Making electrical steel is precise—every step impacts its magnetic performance. Here’s the process:

1. Melting and Casting

• Process: Raw materials (iron ore, silicon, manganese) are melted in an electric arc furnace (EAF). Silicon is added to reach 1–4.5% (higher silicon = lower core loss but more brittleness). The molten steel is cast into slabs (200–300 mm thick) via continuous casting.
• Key Goal: Keep carbon and sulfur ultra-low (<0.005% each) – even tiny amounts ruin magnetic performance.

2. Hot Rolling

• Process: Slabs are heated to 1100–1200°C (red-hot) and rolled into thick coils (2–5 mm thick). Hot rolling breaks down large iron grains, preparing the steel for cold rolling.
• Key Tip: Slow cooling after hot rolling prevents brittleness (critical for high-silicon grades).

3. Cold Rolling (Most Critical Step!)

Cold rolling thins the steel and aligns its grains (for magnetic performance):

• Non-Oriented Electrical Steel (NOES): Rolled to 0.10–0.50 mm thick in one pass – grains stay random (uniform permeability).
• Grain-Oriented Electrical Steel (GOES): Rolled in two passes: first to 1–2 mm, then annealed (heated) to align grains, then rolled again to 0.15–0.30 mm – grains line up in one direction (max permeability along that axis).

4. Heat Treatment

• Annealing: Cold-rolled sheets are heated to 800–1100°C in a protective atmosphere (to avoid oxidation). This:
  • Softens the steel (improves workability).
  • Aligns grains (for GOES, creates a “Goss texture” – grains face the rolling direction, boosting permeability).
  • Reduces internal stress (prevents warping in use).
• Decarburization: For high-grade GOES, annealing in a low-carbon atmosphere removes any remaining carbon (<0.003%) – critical for low core loss.

5. Surface Insulation

• Process: A thin insulation layer (0.5–2 μm) is applied to the sheets. Common coatings:
  • Inorganic Coatings: Magnesium phosphate (for GOES) – heat-resistant and prevents shorting between stacked sheets.
  • Organic Coatings: Epoxy (for NOES) – cheaper and easier to apply (used in small motors).
• Key Goal: Ensure the coating is thin (doesn’t add bulk) but effective (no electrical leakage between sheets).

6. Cutting and Shaping

• Process: Coils are cut into sheets or stamped into shapes (e.g., transformer core laminations, motor stator teeth).
• Key Tip: For GOES, cut along the grain direction (to keep permeability high); for NOES, cutting direction doesn’t matter.

7. Quality Control and Inspection

• Magnetic Testing: Measures core loss (using a Epstein frame) and permeability (with a magnetometer) – must meet industry standards (e.g., IEC 60404 for core loss).
• Chemical Analysis: Checks silicon, carbon, and sulfur levels – ultra-low carbon is non-negotiable.
• Dimensional Checks: Verifies sheet thickness (±0.005 mm for thin grades) and edge smoothness (no burrs >0.01 mm).
• Coating Inspection: Tests insulation resistance (no electrical leakage between sheets) and adhesion (coating doesn’t peel during bending).

4. Case Studies: Electrical Steel in Action

Real-world examples show how electrical steel improves efficiency and reduces costs. Here are 3 key cases:

Case Study 1: EV Motor Efficiency with Low-Loss Electrical Steel

An EV manufacturer struggled with short battery range—their motors used regular steel cores, which had high core loss (2.5 W/kg), wasting energy as heat.

Solution: Switched to high-silicon NOES (3.5% silicon, core loss = 0.8 W/kg) for motor stators and rotors.
Results:

• Core loss reduced by 68% – Motor heat dropped by 40%, so less energy was used for cooling.
• EV range increased by 15% (from 300 km to 345 km) – Critical for customer satisfaction.
• Manufacturing costs up by 5% (low-loss steel is slightly more expensive) but offset by higher EV sales (better range = more buyers).

Why it worked: The high-silicon steel’s high electrical resistivity slowed eddy currents, cutting core loss and saving battery energy.

Case Study 2: Wind Turbine Generator with GOES

A wind farm operator had high energy waste—their generators used NOES, which had core loss of 1.5 W/kg, reducing power output.

Solution: Upgraded to grain-oriented electrical steel (GOES, core loss = 0.3 W/kg) for generator cores.
Results:

• Core loss reduced by 80% – Generator efficiency improved from 92% to 96%.
• Annual energy output increased by 4% (per turbine) – For a 100-turbine farm, that’s 4 extra GWh/year (enough to power 300 homes).
• Payback time: 2 years – The extra energy revenue covered the cost of upgrading the cores.

Why it worked: GOES’s directional permeability conducted magnetic fields more efficiently, cutting energy waste in the generator.

Case Study 3: Household Fridge Motors with Thin NOES

A fridge brand wanted to make smaller, quieter fridges—but their existing motors used thick NOES (0.50 mm), which were bulky and had high core loss (1.2 W/kg).

Solution: Switched to thin NOES (0.20 mm, core loss = 0.6 W/kg) for motor cores.
Results:

• Motor size reduced by 30% – Fridges became 15% slimmer (a key selling point).
• Core loss cut by 50% – Fridge energy use dropped by 8% (meets energy efficiency standards like ENERGY STAR).
• Noise reduced by 10 dB – Quieter fridges had 25% higher customer ratings.

Why it worked: Thin NOES sheets reduced eddy currents (core loss) and let the motor be designed smaller, while still being strong enough for fridge use.

5. Electrical Steel vs. Other Materials

Electrical Steel is the only material designed for magnetic efficiency—here’s how it compares to alternatives:

Key Takeaway: Electrical Steel is the only material with low core loss and high permeability—alternatives waste too much energy or can’t conduct magnetic fields. GOES is best for transformers (directional needs), while NOES is better for motors (rotating fields).

Yigu Technology’s Perspective on Electrical Steel

At Yigu Technology, Electrical Steel is our go-to for clients building efficient electrical devices—from EV motors to wind turbines. We recommend NOES for most motor applications (cost-effective, easy to shape) and GOES for large transformers (lowest core loss, maximum energy savings). We also help clients optimize thickness: thinner sheets (0.15–0.20 mm) cut core loss but cost more, so we balance performance and budget. For EV and renewable energy clients, low-loss electrical steel is a “must-have”—it directly improves battery life and energy output. Our quality checks focus on core loss and grain alignment, ensuring every batch meets the highest standards for efficiency.