If you need a material for high-wear, high-stress components—like bearings, gears, or automotive transmission parts—EN31 52100 bearing steel is a top choice. Renowned for its excellent wear resistance and high fatigue resistance, it solves the problem of short component lifespans in demanding applications. This guide covers its key traits, real-world uses, and how it outperforms alternatives.
What are the core properties of EN31 52100?
EN31 52100 is a high-carbon chromium bearing steel. Its chemistry and heat treatment are tailored to deliver the hardness and toughness needed for rolling or sliding components. Tight chemical controls ensure consistent performance.
Chemical composition
The elements work together to provide high hardness after heat treatment and excellent fatigue strength.
| Element | Content Range (%) | Key Role |
|---|---|---|
| Carbon (C) | 0.95 – 1.10 | Critical for achieving high hardness after heat treatment |
| Chromium (Cr) | 1.30 – 1.60 | Boosts hardenability, wear resistance, and fatigue strength |
| Manganese (Mn) | 0.25 – 0.45 | Improves hardenability, prevents brittleness |
| Silicon (Si) | 0.15 – 0.35 | Strengthens matrix, enhances heat treatment response |
| Phosphorus (P) | ≤ 0.025 | Minimized to avoid cold brittleness |
| Sulfur (S) | ≤ 0.025 | Kept low to maintain toughness |
Physical properties
These traits are essential for design and manufacturing calculations.
- Density: 7.81 g/cm³
- Melting point: 1,420–1,460°C
- Thermal conductivity: 42 W/(m·K) at 20°C
- Thermal expansion: 11.5 × 10⁻⁶/°C (20–100°C)
- Electrical resistivity: 0.20 Ω·mm²/m at 20°C
Mechanical properties
EN31 52100’s mechanical performance shines after quenching and tempering. Here’s how it compares to a common carbon steel.
| Property | EN31 52100 (Quenched & Tempered) | 1045 Carbon Steel |
|---|---|---|
| Tensile strength | 1,800 – 2,200 MPa | 800 – 1,000 MPa |
| Yield strength | 1,500 – 1,800 MPa | 600 – 750 MPa |
| Hardness (HRC) | 58 – 62 | 28 – 32 |
| Impact toughness | 15 – 25 J | 40 – 50 J |
| Elongation | 5 – 8% | 15 – 20% |
| Fatigue resistance | 600 – 700 MPa (10⁷ cycles) | 300 – 350 MPa (10⁷ cycles) |
A bearing manufacturer switched from 1045 steel to EN31 52100 for electric motor ball bearings. The EN31 bearings lasted 5 times longer—from 2,000 to 10,000 operating hours—and reduced friction-related energy loss by 8%.
Other key properties
- Wear resistance: Excellent. High hardness makes it 3–4 times more wear-resistant than 1045 steel.
- Fatigue strength: Outperforms carbon steel by 80–130%. Components last longer under repeated stress.
- Corrosion resistance: Better than plain carbon steel. Chromium adds a thin oxide layer that slows rusting.
- High-temperature strength: Maintains hardness and strength up to 200°C.
- Weldability: Moderate. Requires preheating to 200–300°C to avoid cracking. Post-weld heat treatment is recommended.
- Formability: Best shaped via forging or cold rolling. Hot forming is easier than cold forming due to high carbon content.
Where is EN31 52100 used?
EN31 52100’s combination of wear resistance and fatigue strength makes it indispensable across industries.
Bearings (primary application)
It’s the gold standard for bearing components where low friction and long life are critical.
- Ball bearings: Inner and outer rings and balls for electric motors, pumps, and automotive wheels
- Roller bearings: Cylinders or tapered rollers for heavy-duty machinery like construction equipment
- Thrust bearings: Plates and rollers handling axial loads in gearboxes or turbines
Automotive
Automotive relies on it for high-stress, high-wear components.
- Engine components: Camshafts, valve lifters, and timing gears resist wear from metal-to-metal contact
- Transmission components: Gear teeth and shafts handle torque and repeated shifting
- Steering components: Tie rod ends and steering knuckles withstand road vibrations
Industrial machinery
Industrial equipment uses it for durable, low-maintenance parts.
- Gears: High-precision gear teeth in conveyors, mixers, and machine tools
- Shafts: Drive shafts and spindle shafts resist bending and wear
- Machine parts: Guide rails and sliding blocks for CNC machines or presses
Aerospace and railway
- Aerospace: Aircraft engine bearings and landing gear components withstand extreme stress and temperature changes
- Railway: Freight train axles handle heavy loads and vibration
A railway manufacturer used EN31 52100 for freight train axles. The axles lasted 3 times longer than HSLA steel—from 500,000 to 1.5 million km—and reduced maintenance costs by 40%.
How is EN31 52100 manufactured?
EN31 52100 requires precise manufacturing and heat treatment to unlock its full potential.
Steelmaking and heat treatment
- Steelmaking: Electric arc furnace (EAF) is most common. Ensures tight control over impurities critical for bearing performance.
- Quenching and tempering: Heat to 830–860°C, quench in oil or water, then temper at 150–200°C. Achieves 58–62 HRC hardness while reducing brittleness.
- Carburizing (optional): For parts needing hard surface and tough core like gear teeth. Creates 0.5–1 mm hard surface layer at 60+ HRC with tough core.
- Nitriding (optional): Enhances surface hardness and corrosion resistance. Forms thin hard layer of 5–15 μm at 70+ HRC.
Forming and surface treatment
- Hot rolling: Heats to 1,100–1,200°C and rolls into bars, rods, or sheets for bearing blanks.
- Forging: Heats and hammers into complex shapes like landing gear components.
- Chromium plating: Adds corrosion resistance and reduces friction for bearings.
- Titanium nitride coating: Harder than steel for cutting tools or high-wear gears.
- Shot peening: Creates compressive stress, improving fatigue resistance.
How does EN31 52100 compare to other materials?
Choosing EN31 52100 means understanding its advantages over alternatives.
| Material | Key Comparison Points |
|---|---|
| SUJ2 | Nearly identical. SUJ2 is the Japanese standard for 52100. No major performance differences. |
| 440C stainless | 440C has better corrosion resistance but lower fatigue strength at 500–550 vs. 600–700 MPa. EN31 is 20% cheaper. |
| 1045 carbon | EN31 is 125–175% stronger, 3–4 times more wear-resistant. Costs 50% more but lasts 3–5 times longer. |
| AISI 4340 | 4340 is tougher with 40–60 J impact but less wear-resistant. EN31 is 30% cheaper and has 2 times better wear resistance. |
| 304 stainless | 304 has better corrosion resistance but EN31 is 2–3 times stronger and more wear-resistant. EN31 is 20% cheaper. |
| 7075 aluminum | 7075 is 3 times lighter but EN31 is 2 times stronger and 5–10 times more wear-resistant. EN31 is 10% cheaper. |
Key takeaways:
- EN31 52100 offers superior wear resistance and fatigue strength compared to carbon and stainless steels
- It’s more cost-effective than specialty alloys for wear-focused applications
- Its high hardness makes it ideal for bearings, gears, and high-stress components
Conclusion
EN31 52100 bearing steel delivers exceptional wear resistance and fatigue strength for high-stress, high-wear applications. Its high carbon and chromium content, combined with precise heat treatment, provides hardness up to 62 HRC and fatigue resistance up to 700 MPa. For bearings, automotive transmission parts, and industrial gears where component life matters, it offers proven reliability and long service life.
FAQ
Can EN31 52100 be used for high-temperature applications like aircraft engines?
Yes, it performs reliably up to 200°C. For temperatures above 200°C, use custom grades with added molybdenum for enhanced heat resistance, or pair it with a heat-resistant coating.
Is EN31 52100 hard to machine?
It’s harder to machine than low-carbon steels due to its high hardness of 58–62 HRC. For machining, use carbide tools instead of high-speed steel. Anneal the steel first to soften it to 20–25 HRC if possible. Post-machining heat treatment restores full hardness.
What’s the typical lead time for EN31 52100 bars or bearing blanks?
Standard hot-rolled bars take 2–3 weeks. Cold-rolled bars or bearing blanks with polishing take 3–4 weeks. Custom grades like nitrided or carburized parts take 4–6 weeks due to extra heat treatment steps.
Does EN31 52100 require special welding procedures?
Yes. Preheat to 200–300°C to avoid cracking. Use low-hydrogen electrodes. Post-weld heat treatment is recommended to restore full toughness. For critical components, consider mechanical joining methods instead of welding.
How does EN31 52100 compare to SUJ2?
They are nearly identical. EN31 is the British standard grade, while SUJ2 is the Japanese standard for 52100 steel. Chemical composition, mechanical properties, and performance characteristics are essentially the same.
Discuss Your Projects with Yigu Rapid Prototyping
At Yigu Rapid Prototyping, we supply EN31 52100 bearing steel for bearings, gears, and automotive transmission components. Our material meets strict chemical and mechanical standards, and we offer custom heat treatment, shot peening, and chromium plating services. Contact us to discuss your next high-wear, high-stress application.