Steel 18CrNi8-S
Heat-treated state
EN 18CrNi8
Bar condition ordered when blanks are to be cold-sheared or cropped instead of sawn.
Values for the S condition
Other 18CrNi8 tempers and conditions
18CrNi8 is listed in 10 conditions; see the grade overview at 18CrNi8.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
treated to a ferrite-pearlite structure with hardness range | Choose when uniform, reproducible machining behaviour and low distortion in carburizing are required (automotive gear blanks). | 420 | 700 | 19 | 195 HB | 7.2 % IACS |
soft annealed, max 229 HB | Pick for maximum machinability and cold-working ability before carburizing; softest standard delivery condition. | 440 | 740 | 18 | 205 HB | — |
SThis page treated for cold shearing (max 255 HB) | Bar condition ordered when blanks are to be cold-sheared or cropped instead of sawn. | 520 | 830 | 15 | 21 HRC | 6.9 % IACS |
HRDefault Hot rolled | Standard mill delivery for forging, rough machining and subsequent carburizing; hardness is uncontrolled and can be high because of the Cr-Ni content. | 570 | 870 | 13 | 25 HRC | 6.9 % IACS |
austenitized ~870 °C, air cooled | Used to homogenize forgings before final annealing; with 2 % Cr + 2 % Ni air cooling already produces a hard bainitic/martensitic structure. | 670 | 980 | 12 | 29 HRC | 6.9 % IACS |
Cold rolled | Strip form for stamped, cold-formed parts that are subsequently case hardened. | 690 | 860 | 9 | 24 HRC | 6.9 % IACS |
Cold drawn | Choose for close-tolerance, bright-surface small-diameter parts machined on automatic lathes before carburizing. | 730 | 900 | 9 | 26 HRC | 6.9 % IACS |
Quenched and tempered | Non-carburized through-hardened option for shafts and fasteners where toughness matters more than surface wear. | 830 | 1,000 | 14 | 31 HRC | — |
Carburized and hardened | The functional condition for gears and shafts: hard wear-resistant case with compressive residual stress over a tough 1100–1300 MPa core. | 880 | 1,250 | 9 | 60 HRC | — |
Blank hardened | Reference condition of EN 10084 used to verify core properties; also used for small parts needing through-hardened high strength. | 900 | 1,300 | 9 | 41 HRC | — |
What is 18CrNi8-S?
18CrNi8-S is 18CrNi8 heat treated to S — bar condition ordered when blanks are to be cold-sheared or cropped instead of sawn. 18CrNi8-S has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi). 18CrNi8-S has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). HR is the default condition FabDigit quotes; S is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
18CrNi8-S properties
Typical room-temperature values for 18CrNi8-S; 23 are specific to this condition. Other listed values are 18CrNi8 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
18CrNi8-S has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
18CrNi8-S has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18CrNi8-S is rated for continuous service to 200°C (392 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
18CrNi8-S conducts electricity at 6.9 % IACS, worse than 76% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18CrNi8-S takes about 33 MJ of energy and emits 2.3 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability6
18CrNi8-S's machinability is fair (44/100, worse than 71% of steel grades); weldability fair (35/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18CrNi8-S
Is 18CrNi8 easy to machine?
Machine in the soft-annealed or +FP condition (≤229 HB) with carbide tooling, moderate speeds and generous coolant; leave 0.2–0.5 mm stock for post-carburizing grinding since 58–62 HRC surfaces need CBN/grinding only.
Can 18CrNi8 be welded?
Weld only in the annealed state with 200–300 °C preheat, low-hydrogen or matching-Ni consumables, then re-normalize/anneal; carburized surfaces must not be welded (cracking, case decarburization).
Can 18CrNi8 be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling and mandatory post-forge normalize + soft anneal; cold heading/upsetting only in the annealed or spheroidized condition.
What surface finishes work on 18CrNi8?
No anodizing (steel); protect with oil, phosphate, black oxide, zinc-nickel or hard chrome; ground and superfinished gear flanks improve fatigue and pitting life, shot peening adds compressive stress.
18CrNi8 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 | 0.15 – 0.2 | 0.18 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.6 | 0.5 |
| Pmax (EN 10084) | ≤ 0.03 | — |
| Smax; low-S or controlled-S variants available | ≤ 0.04 | — |
| Cr | 1.8 – 2.1 | 1.95 |
| Ni | 1.8 – 2.1 | 1.95 |
| Moresidual, not intentionally added | ≤ 0.1 | — |
| Fe | balance | — |
18CrNi8-S — frequently asked
What is 18CrNi8-S used for?
18CrNi8-S is typically used for gears, industrial drive shafts and pins. In short: high-strength Ni-Cr bar.
What is the yield strength of 18CrNi8-S?
18CrNi8-S has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 18CrNi8-S easy to machine?
Not especially — machinability is rated fair (44/100, worse than 71% of steel grades). Machine in the soft-annealed or +FP condition (≤229 HB) with carbide tooling, moderate speeds and generous coolant; leave 0.2–0.5 mm stock for post-carburizing grinding since 58–62 HRC surfaces need CBN/grinding only.
Can 18CrNi8-S be welded?
With care — weldability is rated fair (35/100). Weld only in the annealed state with 200–300 °C preheat, low-hydrogen or matching-Ni consumables, then re-normalize/anneal; carburized surfaces must not be welded (cracking, case decarburization).
What surface finishes work on 18CrNi8-S?
No anodizing (steel); protect with oil, phosphate, black oxide, zinc-nickel or hard chrome; ground and superfinished gear flanks improve fatigue and pitting life, shot peening adds compressive stress.
Can 18CrNi8-S be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling and mandatory post-forge normalize + soft anneal; cold heading/upsetting only in the annealed or spheroidized condition.
What is the maximum service temperature of 18CrNi8-S?
18CrNi8-S is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 18CrNi8-HR and 18CrNi8-BG?
HR is the default condition — standard mill delivery for forging, rough machining and subsequent carburizing; hardness is uncontrolled and can be high because of the Cr-Ni content. BG: reference condition of EN 10084 used to verify core properties; also used for small parts needing through-hardened high strength. Yield strength is 570 MPa in HR versus 900 MPa in BG.
Can FabDigit make parts in 18CrNi8-S?
Yes — 18CrNi8-S is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- DIN 17210 (withdrawn) / SEW 550 case hardening steel data — DIN / VDEh (1987)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4A — Steel Heat Treating Fundamentals and Processes — ASM International (2013)
- Case-hardening steel 18CrNi8 / 1.5920 bar datasheet — Ovako / Böhler / Lucchini-type mill data (2022)
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.