Steel 18CrNi8-FP
Heat-treated state
EN 18CrNi8
Choose when uniform, reproducible machining behaviour and low distortion in carburizing are required (automotive gear blanks).
Values for the FP 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 |
|---|---|---|---|---|---|---|
FPThis page 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 | — |
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-FP?
18CrNi8-FP is 18CrNi8 heat treated to FP — choose when uniform, reproducible machining behaviour and low distortion in carburizing are required (automotive gear blanks). 18CrNi8-FP has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 53% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi). 18CrNi8-FP 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; FP 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
18CrNi8-FP properties
Typical room-temperature values for 18CrNi8-FP; 22 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-FP 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-FP has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 53% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18CrNi8-FP is rated for continuous service to 200°C (392 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
18CrNi8-FP conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18CrNi8-FP 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-FP's machinability is fair (52/100, better than 52% of steel grades); weldability fair (40/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18CrNi8-FP
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-FP — frequently asked
What is 18CrNi8-FP used for?
18CrNi8-FP is typically used for gears, industrial drive shafts and pins. In short: high-strength Ni-Cr bar.
What is the yield strength of 18CrNi8-FP?
18CrNi8-FP has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 18CrNi8-FP easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% 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-FP be welded?
With care — weldability is rated fair (40/100). 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-FP?
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-FP 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-FP?
18CrNi8-FP 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-FP?
Yes — 18CrNi8-FP 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.