Steel 100CrMnMoSi8-4-6-S2
Heat-treated state
EN 100CrMnMoSi8-4-6
S2 = hardened + stabilized ~250 °C, 56–59 HRC
For hot-running applications to ~250 °C where some hardness is traded for thermal dimensional stability.
Values for the S2 condition
Other 100CrMnMoSi8-4-6 tempers and conditions
100CrMnMoSi8-4-6 is listed in 8 conditions; see the grade overview at 100CrMnMoSi8-4-6.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ADefault Annealed | Standard delivery condition for bars, tubes and forged ring blanks — soft enough for turning before hardening. | 430 | 720 | 14 | 220 HB | — |
Soft annealed then cold drawn / peeled-ground bar | Precision bar for small rollers, pins and bushings machined from bar without further softening. | 620 | 800 | 8 | 24 HRC | 4.4 % IACS |
Hot rolled | Mill condition before annealing; very hard and brittle because the alloy air-hardens on cooling — always anneal before machining. | 950 | 1,250 | 6 | 41 HRC | 4.3 % IACS |
Hardened + stabilized ~300 °C, 54–57 HRC | Highest stabilization class of this grade, for bearings and rolls operating near 300 °C. | 1,650 | 1,900 | 2 | 55 HRC | 4 % IACS |
S2This page Hardened + stabilized ~250 °C, 56–59 HRC | For hot-running applications to ~250 °C where some hardness is traded for thermal dimensional stability. | 1,750 | 2,000 | 1.5 | 57 HRC | 3.9 % IACS |
Bainite hardened (austempered), 58–62 HRC | Choose for large wind-turbine and rolling-mill bearings needing high toughness, compressive surface stress and low distortion/crack risk. | 1,800 | 2,150 | 2 | 60 HRC | — |
Hardened + dimensionally stabilized ~200 °C, 58–61 HRC | Stabilized for bearings running continuously up to about 200 °C with tight dimensional tolerance. | 1,850 | 2,150 | 1 | 59 HRC | 3.8 % IACS |
Martensitic hardened + tempered ~160 °C, 60–64 HRC | Standard through-hardened bearing condition for maximum contact fatigue capacity in large rings and rollers. | 2,000 | 2,300 | 1 | 62 HRC | — |
What is 100CrMnMoSi8-4-6-S2?
100CrMnMoSi8-4-6-S2 is 100CrMnMoSi8-4-6 heat treated to S2 — for hot-running applications to ~250 °C where some hardness is traded for thermal dimensional stability. 100CrMnMoSi8-4-6-S2 has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 1.5% and the elastic modulus is 208 GPa (30.2 Msi). 100CrMnMoSi8-4-6-S2 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F). +A is the default condition FabDigit quotes; S2 is available on request or by drawing note.
Advantages
- High strength — 1,750 MPa (254 ksi), better than 99% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
Limitations
- Difficult to machine — 6/100, worse than 100% of steel grades
- Difficult to weld — 2/100, worse than 100% of steel grades
- Limited ductility — 1.5%, worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
100CrMnMoSi8-4-6-S2 properties
Typical room-temperature values for 100CrMnMoSi8-4-6-S2; 22 are specific to this condition. Other listed values are 100CrMnMoSi8-4-6 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
100CrMnMoSi8-4-6-S2 has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
100CrMnMoSi8-4-6-S2 has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 1.5% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
100CrMnMoSi8-4-6-S2 is rated for continuous service to 250°C (482 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
100CrMnMoSi8-4-6-S2 has an electrical resistivity of 4.4×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 100CrMnMoSi8-4-6-S2 takes about 34 MJ of energy and emits 2.5 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
100CrMnMoSi8-4-6-S2's machinability is not recommended (6/100, worse than 100% of steel grades); weldability not recommended (2/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 100CrMnMoSi8-4-6-S2
Is 100CrMnMoSi8-4-6 easy to machine?
Turn/drill only in the spheroidize-annealed condition with coated carbide and rigid setups; after hardening the part is finished by grinding, honing or hard turning with CBN.
Can 100CrMnMoSi8-4-6 be welded?
Essentially non-weldable (~1 %C, air-hardening); if repair is unavoidable use preheat 300–400 °C, low-hydrogen filler and immediate post-weld temper, accepting reduced fatigue life.
Can 100CrMnMoSi8-4-6 be formed, bent or molded?
Hot forge 1100 → 850 °C with slow controlled cooling (air-hardening steel cracks if quenched from forging), then spheroidize anneal ~790 °C; cold forming limited to light coining of annealed stock.
What surface finishes work on 100CrMnMoSi8-4-6?
No anodizing; protect with oil, phosphate, black oxide or thin dense chrome, and grind/lap raceways to Ra < 0.1 µm for full bearing life.
100CrMnMoSi8-4-6 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 |
|---|---|---|
| C | 0.93 – 1.05 | 0.99 |
| Si | 0.4 – 0.6 | 0.5 |
| Mn | 0.8 – 1.1 | 0.95 |
| Cr | 1.8 – 2.05 | 1.9 |
| Mo | 0.5 – 0.6 | 0.55 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Curesidual, max | ≤ 0.3 | — |
| Niresidual, max | ≤ 0.3 | — |
| Fe | balance | — |
100CrMnMoSi8-4-6-S2 — frequently asked
What is 100CrMnMoSi8-4-6-S2 used for?
100CrMnMoSi8-4-6-S2 is typically used for very large rolling bearings, heavy machinery bearing rings and mill and crusher bearings. In short: deepest-hardening bearing grade; air-hardening, dimensionally stable; for very large bearings.
What is the yield strength of 100CrMnMoSi8-4-6-S2?
100CrMnMoSi8-4-6-S2 has a typical yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 100CrMnMoSi8-4-6-S2 easy to machine?
Not especially — machinability is rated not recommended (6/100, worse than 100% of steel grades). Turn/drill only in the spheroidize-annealed condition with coated carbide and rigid setups; after hardening the part is finished by grinding, honing or hard turning with CBN.
Can 100CrMnMoSi8-4-6-S2 be welded?
Not readily — weldability is rated not recommended (2/100). Essentially non-weldable (~1 %C, air-hardening); if repair is unavoidable use preheat 300–400 °C, low-hydrogen filler and immediate post-weld temper, accepting reduced fatigue life.
What surface finishes work on 100CrMnMoSi8-4-6-S2?
No anodizing; protect with oil, phosphate, black oxide or thin dense chrome, and grind/lap raceways to Ra < 0.1 µm for full bearing life.
Can 100CrMnMoSi8-4-6-S2 be formed, bent or molded?
Hot forge 1100 → 850 °C with slow controlled cooling (air-hardening steel cracks if quenched from forging), then spheroidize anneal ~790 °C; cold forming limited to light coining of annealed stock.
What is the maximum service temperature of 100CrMnMoSi8-4-6-S2?
100CrMnMoSi8-4-6-S2 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 100CrMnMoSi8-4-6 +A and 100CrMnMoSi8-4-6-M60?
+A is the default condition — standard delivery condition for bars, tubes and forged ring blanks — soft enough for turning before hardening. M60: standard through-hardened bearing condition for maximum contact fatigue capacity in large rings and rollers. Yield strength is 430 MPa in +A versus 2,000 MPa in M60.
Sources
- ISO 683-17 — Heat-treatable steels, alloy steels and free-cutting steels: Ball and roller bearing steels — ISO (2014)
- DIN EN ISO 683-17 / Werkstoff-Nr. 1.3539 — DIN (2015)
- Bearing steel grades for large bearings (100CrMnMoSi8-4-6) — Ovako / Saarstahl / Gerdau special steel (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Rolling Bearing Analysis / bearing steel metallurgy chapters — Wiley / SKF technical literature (2007)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.