Steel EN31
BS EN31 · AISI/SAE 52100 · EN 1.3505 · GB GCr15
EN31 is a high-carbon chromium through-hardening bearing steel in the British Standard series, equivalent to AISI 52100, 1.3505 and GCr15.
Reference datasheet — EN31 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
EN31 tempers and conditions
EN31 is supplied in 9 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard stocked condition — soft, spheroidised carbides for machining and cold forming before hardening. | 420 | 690 | 25 | 195 HB | 46 W/m·K |
Hot rolled | As-rolled bar/billet for onward forging or annealing; too hard and brittle for direct machining. | 550 | 900 | 12 | 29 HRC | 7.8 % IACS |
Cold drawn | Close-tolerance bright bar for precision turning; slightly harder than annealed with better surface and straightness. | 600 | 780 | 12 | 20 HRC | 7.8 % IACS |
Normalized | Used to break up carbide networks in forgings before spheroidizing; not a delivery condition for machining. | 620 | 1,000 | 10 | 33 HRC | 7.8 % IACS |
Q&T, high temper 35–45 HRC | Tough, machinable hardened condition for die bodies, punch shanks and heavily loaded structural parts. | 1,150 | 1,350 | 8 | 40 HRC | — |
Q&T, medium temper 50–56 HRC | Chosen for tooling and shafts needing more toughness than a bearing race; slight loss of wear resistance. | 1,550 | 1,800 | 4 | 53 HRC | — |
Hardened & Stabilized | Higher tempering for dimensional stability at elevated bearing temperatures (S1/SN designations), trading a little hardness. | 1,750 | 2,050 | 1.5 | 59 HRC | — |
Hardened & Tempered 60–64 HRC | The classic bearing condition — maximum hardness and rolling contact fatigue life; low toughness, service ≤120–150 °C. | 1,900 | 2,250 | 1 | 62 HRC | — |
Induction hardened | Selective surface hardening for large rings, rollers and shafts where a tough core plus hard raceway is wanted. | 1,900 | 2,200 | 1 | 61 HRC | 7 % IACS |
What is EN31?
EN31 is a high-carbon chromium through-hardening bearing steel in the British Standard series, equivalent to AISI 52100, 1.3505 and GCr15. Engineers choose it for rolling-element bearings and precision tooling because it hardens to 60–64 HRC with high compressive strength and dimensional stability after stabilising treatment; it is stocked as hot-rolled, spheroidise-annealed, normalised and cold-drawn bar, tube and ball/roller blanks. Annealed default values are 420 MPa yield, 690 MPa tensile strength, 25% elongation, 195 HB (92 HRB) and 46 W/m·K thermal conductivity. It is effectively non-weldable, has no corrosion resistance and machines at only about 45% of free-cutting steel; use 42CrMo4 where welding or higher toughness is required. EN31 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,424°C (2,595 °F). EN31 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
What is EN31 used for?
- bearings
- gauges
- precision tools
- rollers
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
EN31 properties
Typical room-temperature values for EN31-ANN; bars are the position among steel grades.
Physical3
EN31 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,424°C (2,595 °F).
Mechanical16
EN31 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
EN31 is rated for continuous service to 150°C (302 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
EN31 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of EN31 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability8
EN31's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (15/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. EN31 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with EN31
Is EN31 easy to machine?
Machine only in the spheroidize-annealed state (~40% of 1212) with rigid setups and carbide tooling; hardened 60+ HRC parts require CBN hard turning or grinding.
Can EN31 be welded?
Effectively non-weldable — high carbon equivalent gives untempered martensite and cracks; if unavoidable, preheat 300–400 °C, low-hydrogen filler and immediate stress relief.
Can EN31 be formed, bent or molded?
Cold heading/ball rolling is done only on soft annealed stock; hot forge 1050–1150 °C, do not finish below ~880 °C, then slow cool and spheroidize anneal.
EN31 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CBS 970 EN31; AISI 52100 narrows to 0.93–1.05 | 0.9 – 1.2 | 1 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn52100/GCr15 typically 0.25–0.45 | 0.3 – 0.75 | 0.5 |
| Cr | 1 – 1.6 | 1.4 |
| Pbearing quality (GB/T 18254) limits to 0.025 | ≤ 0.05 | 0.02 |
| Sbearing quality limits to 0.025 | ≤ 0.05 | 0.02 |
| Niresidual | ≤ 0.3 | 0.1 |
| Curesidual | ≤ 0.25 | 0.1 |
| Moresidual | ≤ 0.1 | 0.03 |
| Ovacuum-degassed bearing quality, ppm-level control | ≤ 0 | 8×10⁻⁴ |
| Fe | balance |
What surface finishes work on EN31?
Cannot be anodized; typical finishes are hard grinding/lapping to mirror plus preservative oil, black oxide, manganese phosphate, zinc or hard chrome plating — bake after plating to avoid hydrogen embrittlement.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel EN31 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does EN31 cost?
EN31 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
EN31 — frequently asked
What is EN31 used for?
EN31 is typically used for bearings, gauges, precision tools and rollers. In short: classic 52100 bearing steel; through-hardens to 60–64 HRC; effectively non-weldable.
What is the yield strength of EN31?
EN31 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is EN31 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine only in the spheroidize-annealed state (~40% of 1212) with rigid setups and carbide tooling; hardened 60+ HRC parts require CBN hard turning or grinding.
Can EN31 be welded?
Not readily — weldability is rated poor (15/100). Effectively non-weldable — high carbon equivalent gives untempered martensite and cracks; if unavoidable, preheat 300–400 °C, low-hydrogen filler and immediate stress relief.
What surface finishes work on EN31?
Cannot be anodized; typical finishes are hard grinding/lapping to mirror plus preservative oil, black oxide, manganese phosphate, zinc or hard chrome plating — bake after plating to avoid hydrogen embrittlement.
Can EN31 be formed, bent or molded?
Cold heading/ball rolling is done only on soft annealed stock; hot forge 1050–1150 °C, do not finish below ~880 °C, then slow cool and spheroidize anneal.
What is the maximum service temperature of EN31?
EN31 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between EN31-ANN and EN31 QT60-64?
ANN is the default condition — standard stocked condition — soft, spheroidised carbides for machining and cold forming before hardening. QT60-64: the classic bearing condition — maximum hardness and rolling contact fatigue life; low toughness, service ≤120–150 °C. Yield strength is 420 MPa in ANN versus 1,900 MPa in QT60-64.
How much does EN31 cost?
EN31 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- BS 970: Wrought steels — EN31 / 535A99 — BSI (1991)
- ASTM A295 — High-Carbon Anti-Friction Bearing Steel (52100) — ASTM (2020)
- GB/T 18254 (GCr15) — SAC (2016)
- DIN EN ISO 683-17 / Werkstoff 1.3505 — DIN/ISO (2014)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture (rolling contact fatigue) — ASM International (1996)
- Bearing steel 100Cr6 / 52100 datasheet — Ovako / Sandvik (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.