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 breaks down its key traits, real-world uses, and how it outperforms alternatives, so you can build durable, long-lasting products.
1. Core Material Properties of EN31 52100 Bearing Steel
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. Below’s a detailed breakdown:
1.1 Chemical Composition
Its tight chemical controls ensure consistent performance. Typical chemical composition includes:
- 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 and prevents brittleness)
- Silicon (Si): 0.15–0.35% (strengthens the matrix and enhances heat treatment response)
- Phosphorus (P): ≤0.025% (minimized to avoid cold brittleness and reduce fatigue crack risk)
- Sulfur (S): ≤0.025% (kept low to maintain toughness and avoid machining defects)
- Other alloying elements: Trace amounts of nickel or molybdenum (in custom grades) to further enhance toughness.
1.2 Physical Properties
These traits are consistent across EN31 52100 grades—essential for design and manufacturing calculations:
| Physical Property | Typical Value |
|---|---|
| Density | 7.81 g/cm³ |
| Melting point | 1420–1460°C |
| Thermal conductivity | 42 W/(m·K) (20°C) |
| Thermal expansion coefficient | 11.5 × 10⁻⁶/°C (20–100°C) |
| Electrical resistivity | 0.20 Ω·mm²/m (20°C) |
1.3 Mechanical Properties
EN31 52100’s mechanical performance shines after heat treatment (quenching and tempering). Here’s how it compares to a common carbon steel (1045):
| Mechanical Property | EN31 52100 Bearing Steel (Quenched & Tempered) | 1045 Carbon Steel (Quenched & Tempered) |
|---|---|---|
| Tensile strength | 1800–2200 MPa | 800–1000 MPa |
| Yield strength | 1500–1800 MPa | 600–750 MPa |
| Hardness | 58–62 HRC (Rockwell C) | 28–32 HRC (Rockwell C) |
| Impact toughness | 15–25 J (Charpy V-notch, 20°C) | 40–50 J (Charpy V-notch, 20°C) |
| Elongation | 5–8% | 15–20% |
| Fatigue resistance | 600–700 MPa (10⁷ cycles) | 300–350 MPa (10⁷ cycles) |
Key highlights:
- Wear resistance: Its high hardness (58–62 HRC) makes it 3–4x more wear-resistant than 1045 steel—ideal for bearings and gears.
- Fatigue strength: Outperforms carbon steel by 80–130%, so components like shafts or roller bearings last longer under repeated stress.
- Tradeoff note: It has lower ductility than carbon steel, but this is acceptable for applications where wear and fatigue resistance matter most.
1.4 Other Properties
- Excellent wear resistance: Chromium forms hard carbides that resist abrasion—critical for rolling bearings or gears.
- Good corrosion resistance: Better than plain carbon steel; chromium adds a thin oxide layer that slows rusting (can be enhanced with plating).
- High-temperature strength: Maintains hardness and strength up to 200°C—suitable for automotive engine or industrial machinery components.
- Weldability: Moderate (requires preheating to 200–300°C to avoid cracking; post-weld heat treatment is recommended for full toughness).
- Formability: Best shaped via forging or cold rolling (hot forming is easier than cold forming due to its high carbon content).
2. Key Applications of EN31 52100 Bearing Steel
EN31 52100’s combination of wear resistance and fatigue strength makes it indispensable across industries. Below are its top uses, paired with real case studies:
2.1 Bearings (Primary Application)
It’s the gold standard for bearing components, where low friction and long life are critical:
- Ball bearings: Inner/outer rings and balls (used in electric motors, pumps, and automotive wheels).
- Roller bearings: Cylinders or tapered rollers (for heavy-duty machinery like construction equipment).
- Thrust bearings: Plates and rollers (handles axial loads in gearboxes or turbines).
Case Study: A bearing manufacturer switched from 1045 steel to EN31 52100 for electric motor ball bearings. The EN31 52100 bearings lasted 5x longer (from 2,000 to 10,000 operating hours) and reduced friction-related energy loss by 8%—a major benefit for energy-efficient motors.
2.2 Automotive
Automotive relies on it for high-stress, high-wear components:
- Engine components: Camshafts, valve lifters, and timing gears (resist wear from constant 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 and stress).
2.3 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).
2.4 Aerospace & Railway
- Aerospace: Aircraft engine bearings and landing gear components (must withstand extreme stress and temperature changes).
- Railway: Railway wheels (resist wear from track contact) and axles (handle heavy loads and vibration).
Case Study: A railway manufacturer used EN31 52100 for freight train axles. The axles lasted 3x longer than those made from HSLA steel (from 500,000 to 1.5 million km) and reduced maintenance costs by 40%—critical for long-haul freight operations.
3. Manufacturing Techniques for EN31 52100 Bearing Steel
EN31 52100 requires precise manufacturing and heat treatment to unlock its full potential. Here’s how it’s produced:
3.1 Steelmaking Processes
- Electric Arc Furnace (EAF): Most common for EN31 52100. Melts scrap steel, then adds chromium, manganese, and other alloys to hit chemical specs. EAF ensures tight control over impurities (critical for bearing performance).
- Basic Oxygen Furnace (BOF): Used for large-scale production. Blows oxygen into molten iron to reduce carbon, then adds alloys. Less common for EN31 52100 due to stricter impurity requirements.
3.2 Heat Treatment
Heat treatment is the most critical step—without it, EN31 52100 won’t achieve its signature hardness:
- Quenching and tempering: Standard process. Heat steel to 830–860°C (austenitizing), quench in oil or water to harden (forms martensite), then temper at 150–200°C. This achieves 58–62 HRC hardness while reducing brittleness.
- Carburizing (optional): For parts needing a hard surface and tough core (e.g., gear teeth). Heat to 900–950°C in a carbon-rich atmosphere, quench, then temper. Creates a 0.5–1 mm hard surface layer (60+ HRC) with a tough core.
- Nitriding (optional): Enhances surface hardness and corrosion resistance. Heat to 500–550°C in a nitrogen atmosphere. Forms a thin (5–15 μm) hard layer (70+ HRC) ideal for bearings or shafts.
3.3 Forming Processes
EN31 52100 is shaped using processes that accommodate its high carbon content:
- Hot rolling: Heats steel to 1100–1200°C and rolls into bars, rods, or sheets (used for bearing blanks or gear stock).
- Cold rolling: Rolls at room temperature to create precise shapes (e.g., bearing rings) with smooth surfaces.
- Forging: Heats steel and hammers/presses it into complex shapes (e.g., landing gear components or large shafts).
- Extrusion: Pushes heated steel through a die to create long, uniform shapes (e.g., guide rails).
- Stamping: Used for thin, simple parts (e.g., small bearing washers) after softening via annealing.
3.4 Surface Treatment
Surface treatments enhance durability and performance:
- Plating: Chromium plating (adds corrosion resistance and reduces friction for bearings).
- Coating: Titanium nitride (TiN) coating (harder than steel; used for cutting tools or high-wear gears).
- Shot peening: Blasts surface with small metal balls (creates compressive stress, improving fatigue resistance).
- Polishing: Creates a smooth surface (reduces friction in bearings and improves precision).
4. How EN31 52100 Bearing Steel Compares to Other Materials
Choosing EN31 52100 means understanding its advantages over alternatives. Here’s a clear comparison:
| Material Category | Key Comparison Points |
|---|---|
| Other bearing steels (e.g., SUJ2, 440C) | – vs. SUJ2: EN31 52100 is nearly identical (SUJ2 is the Japanese standard for 52100); no major performance differences. – vs. 440C stainless bearing steel: 440C has better corrosion resistance but lower fatigue strength (500–550 vs. 600–700 MPa); EN31 52100 is 20% cheaper. – Best for: EN31 52100 for general bearing use; 440C for wet/corrosive environments. |
| Carbon steels (e.g., 1045) | – Strength: EN31 52100 is 125–175% stronger (tensile 1800–2200 vs. 800–1000 MPa). – Wear resistance: 3–4x better (58–62 vs. 28–32 HRC). – Cost: EN31 52100 is ~50% more expensive but lasts 3–5x longer. |
| High-alloy steels (e.g., AISI 4340) | – Toughness: 4340 is tougher (40–60 vs. 15–25 J impact energy) but less wear-resistant. – Wear resistance: EN31 52100 is 2x better. – Cost: EN31 52100 is ~30% cheaper (better for wear-focused parts). |
| Stainless steels (e.g., 304) | – Corrosion resistance: 304 is better (no rust in moist environments). – Strength/Wear resistance: EN31 52100 is 2–3x stronger and more wear-resistant. – Cost: EN31 52100 is ~20% cheaper (ideal for dry, high-wear applications). |
| Aluminum alloys (e.g., 7075) | – Weight: 7075 is 3x lighter; EN31 52100 is 2x stronger. – Wear resistance: EN31 52100 is 5–10x better (critical for bearings). – Cost: EN31 52100 is ~10% cheaper (better for high-stress, high-wear parts). |
5. Yigu Technology’s Perspective on EN31 52100 Bearing Steel
At Yigu Technology, we see EN31 52100 bearing steel as a reliable workhorse for high-wear, high-stress components. It’s our top recommendation for bearings, automotive transmission parts, and industrial gears—solving clients’ pain points of frequent component replacement and high maintenance costs. For bearing manufacturers, its consistent hardness and fatigue resistance ensure long product life; for automotive clients, it boosts durability in engine and steering parts. While it has lower ductility than carbon steel, its wear and fatigue benefits far outweigh this for most industrial applications. We often pair it with shot peening or chromium plating to further enhance performance.
FAQ About EN31 52100 Bearing Steel
- Can EN31 52100 be used for high-temperature applications (e.g., aircraft engines)?
Yes—its high-temperature strength lets it perform reliably up to 200°C. For temperatures above 200°C, we recommend custom grades with added molybdenum (enhances heat resistance) or pairing 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 (58–62 HRC). For machining, use carbide tools (instead of high-speed steel) and anneal the steel first (softens it to 20–25 HRC) if possible. Post-machining heat treatment will restore its 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 (e.g., nitrided or carburized parts) take 4–6 weeks due to extra heat treatment steps.
