EN31 Bearing Steel Forgings
EN31 is high carbon chromium bearing steel — hard, wear resistant and dimensionally stable after hardening. Its defining requirement is cleanliness, because a single inclusion under a raceway surface will spall the bearing.
- Carbon
- 0.95 – 1.10%
- Chromium
- 1.30 – 1.60%
- Hardened
- 60 – 64 HRC
- Annealed
- 190 – 220 BHN
- Forging Temperature
- 1050 – 1150 °C
- Equivalent
- 100Cr6, SUJ2, 52100
EN31 Bearing Steel Forgings at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Carbon: 0.95 – 1.10%
- Chromium: 1.30 – 1.60%
- Hardened: 60 – 64 HRC
- Annealed: 190 – 220 BHN
- Forging Temperature: 1050 – 1150 °C
- Equivalent: 100Cr6, SUJ2, 52100
Cleanliness Above All
Rolling contact fatigue starts at subsurface inclusions. Bearing steel is therefore bought against strict inclusion ratings and verified in our lab before forging — the one grade where a mill certificate alone is not enough.
- Strict inclusion rating control
- Verified microstructure
- Through hardens to 60–64 HRC
- Excellent dimensional stability
Spheroidise Annealing
EN31 is supplied spheroidise annealed at 190–220 BHN so it can be machined at all. Forging temperature and cooling are controlled to avoid network carbides, which would make subsequent hardening unreliable.
Applications
Bearing inner and outer races, rollers, balls, cam followers, gauges, punches, dies and wear-resistant machine components.
EN31 Chemical Composition and Mechanical Properties
EN31 is a high carbon chromium bearing steel, closely comparable with 100Cr6 (1.3505), AISI 52100 and JIS SUJ2. Its defining requirement is not hardness — which is straightforward to achieve — but cleanliness, because rolling contact fatigue initiates at non-metallic inclusions sitting just below the working surface.
| Property | Typical value |
|---|---|
| Carbon | 0.90 – 1.10% |
| Chromium | 1.00 – 1.60% |
| Manganese | 0.30 – 0.75% |
| Silicon | 0.10 – 0.35% |
| Hardened and low tempered | 60 – 64 HRC |
| Spheroidise annealed for machining | ≈ 190 – 220 HB |
| Forging temperature | 1,050 – 1,150 °C |
| Hardening / tempering | ≈ 830 – 860 °C oil; temper ≈ 150 – 180 °C |
Why Cleanliness Matters More Than Hardness
Under rolling contact, peak shear stress occurs a fraction of a millimetre below the surface rather than at it. An inclusion at that depth concentrates the stress and starts the crack that eventually spalls a bearing race. This is why bearing steel is bought against strict inclusion ratings and verified before forging, and why a mill certificate alone is not treated as sufficient evidence for this grade. See inclusion rating and why bearing races fail.
- Inclusion rating verified before forging
- Spheroidise annealed so it can be machined at all
- Forging and cooling controlled to avoid network carbides
- Ground rather than machined once hardened
People also ask
Why is EN31 supplied spheroidise annealed?
At 190 to 220 BHN it can be machined. In any harder condition it must be ground, which is impractical for rough machining.
What hardness does EN31 reach?
60 to 64 HRC after hardening and low tempering, which is why it is the standard bearing and wear component steel.
Topics covered on this page
- EN31 forging manufacturer India
- bearing steel forging supplier
- 100Cr6 forged rings
- EN31 forging Rajkot
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What hardness does EN31 reach?
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60–64 HRC after hardening and low tempering, which is why it is the standard bearing and wear component steel.
Why does bearing steel need to be so clean?
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Rolling contact fatigue initiates at subsurface inclusions. Cleanliness directly determines bearing life.
Is EN31 machinable?
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Only in the spheroidise annealed condition at 190–220 BHN. After hardening it must be ground.
Do you forge bearing races?
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Yes, seamless rolled rings in EN31 for bearing race applications, supplied annealed and proof machined.