EN 31

EN 31

High-carbon chromium steel for bearing & wear applications

En 31 is a high-carbon chromium steel designed for applications requiring high hardness, wear resistance, dimensional stability and resistance to rolling-contact fatigue.

Common designations: 100cr6 | sae 52100 | din 1.3505 | 535a99

Available forms: round bars | flats | blocks | custom sizes

Performance where contact stress matters

  • EN31 can be hardened to approximately 61–63 hrc, depending on heat treatment and specification.
  • Its high-carbon chromium composition provides strong resistance to abrasive and contact wear.
  • Well suited to components exposed to repeated rolling and contact stresses
  • Suitable for applications where components experience concentrated mechanical loads.
  • Proper heat treatment supports dimensional stability in precision components.
  • The grade is commonly machined in an annealed condition and subsequently ground after hardening.
Category:

Technical Specifications

Parameter EN 31 Specification
Grade EN 31
Material Designation 535A99
Steel Type High-Carbon Chromium Bearing Steel
Material Number 1.3505
European Equivalent 100Cr6
AISI / SAE Equivalent 52100
Japanese Equivalent SUJ2
French Equivalent 100C6
Primary Application Bearing & Wear-Resistant Components
Supply Form Round Bars, Flats, Blocks*
Supply Condition Soft Annealed / Spheroidized / Hardened & Tempered*

Chemical Composition

Element Minimum Maximum
Carbon (C) 0.90% 1.20%
Silicon (Si) 0.10% 0.35%
Manganese (Mn) 0.30% 0.75%
Chromium (Cr) 1.00% 1.60%
Phosphorus (P) — 0.05%
Sulphur (S) — 0.05%
Iron (Fe) Balance —

Applications

EN 31 is a high-carbon chromium steel widely used for components requiring high hardness, wear resistance, and resistance to repeated contact and rolling loads.

Automotive & Bearing Applications

  • Bearing races
  • Ball bearings
  • Roller bearings
  • Bushes
  • Precision bearing components

Industrial

  • Rollers
  • Wear-resistant components
  • Machine components
  • Shafts and spindles
  • Guides and bushes

Engineering & Tooling

  • Gauges
  • Punches
  • Dies
  • Precision components
  • Wear plates and other high-wear parts

EN 31 / 100Cr6 / 52100 is particularly suited to applications where hardness, dimensional stability, wear resistance and rolling-contact fatigue performance are important.

Heat Treatment

Process Typical Temperature / Condition
Hot Forming Approx. 1100–850°C
Normalizing Approx. 870–900°C
Soft Annealing Approx. 780–800°C
Hardening – Water Quench Approx. 800–830°C
Hardening – Oil Quench Approx. 830–870°C
Tempering Approx. 150–180°C
Final Hardness Approx. 62 HRC

Available Forms

Available in the form you need
Round bars
For springs, shafts, and machined engineering components.

Flat bars
Suitable for spring and fabricated component requirements.

Blocks
For machining and specialized component manufacturing.

Custom sizes
Material preparation according to customer requirements.

Supply Condition

From Standard Stock To Custom Requirements

TSI Metals can supply EN 31 in different supply conditions and formats, subject to size, stock availability and applicable specifications:

As-Rolled
Available for requirements where the material is to be supplied in its rolled condition.

Annealed / Soft Condition
Suitable for machining and applications requiring a softer, more machinable material condition.

Spheroidized Annealed
Suitable for improved machinability and subsequent heat-treatment operations.

Hardened & Tempered
Suitable for applications requiring high hardness, wear resistance and dimensional stability.

Full Length
Supplied according to available standard dimensions and stock.

Cut-to-Size
Precision cut according to customer-required dimensions.

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