Steel 18CrNiMo7-6
EN 18CrNiMo7-6
18CrNiMo7-6 (1.6587, close to AISI 9310) is a case-hardening Cr-Ni-Mo alloy steel from the EN 10084 family, carburized to a 58–62 HRC case over a core that stays tough after quench and temper (Q&T 28–32 HRC).
Values for the Annealed condition
18CrNiMo7-6 tempers and conditions
18CrNiMo7-6 is supplied in 9 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
- Spheroidized (+AC)
- Annealed
- Heat Treated (+TH)
- High Shearability (+S)
- Hot Rolled
- Normalized
- Cold Drawn
- Q&T 28-32 HRC
- Carburized 58-62 HRC
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize Annealed | EN 10084 soft-annealed condition with globular carbides, giving the lowest hardness and the best cold formability for extrusion, upsetting and heavy machining before carburizing. | 360 | 590 | 22 | 175 HB | 8 % IACS |
AnnealedDefault soft (spheroidize/sub-critical) annealed bar, ≤229 HB | Standard delivery condition for machining of gear blanks before carburizing. | 370 | 640 | 20 | 200 HB | — |
Heat Treated to Hardness Range | EN 10084 delivery condition treated to a controlled Brinell band (~179–229 HB) so bar and forging stock machines predictably before carburizing. | 450 | 700 | 17 | 205 HB | 8 % IACS |
Treated for High Shearability | EN 10084 condition softened only enough to cap hardness (~≤255 HB) so bar can be cold-sheared into blanks without cracking the shear tooling. | 500 | 780 | 15 | 21 HRC | 8 % IACS |
untreated bar or forging | Mill delivery for stock that will be normalized or annealed by the gear maker. | 500 | 800 | 14 | 23 HRC | 7.8 % IACS |
+N, 870–900 °C air cooled | Uniform fine-grained structure for forgings prior to machining and carburizing. | 550 | 850 | 15 | 24 HRC | 7.8 % IACS |
+C, annealed then cold drawn bright bar | Small-diameter bright bar with tight tolerance for pinion shafts and automatic-lathe work. | 600 | 750 | 10 | 21 HRC | 7.8 % IACS |
Quenched and higher-temperature tempered core condition | Choose when the part is used as a through-hardened shaft rather than a carburized gear. | 800 | 980 | 14 | 30 HRC | — |
Carburized & Hardened | Final service condition for heavy-duty gears: hard wear-resistant case with compressive residual stress over a tough core. | 950 | 1,250 | 9 | 60 HRC | — |
Supply forms, finishes and certifications
Ways 18CrNiMo7-6 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Blank Hardened | Direct quench & low temper without carburizing | Supply form |
What is 18CrNiMo7-6?
18CrNiMo7-6 (1.6587, close to AISI 9310) is a case-hardening Cr-Ni-Mo alloy steel from the EN 10084 family, carburized to a 58–62 HRC case over a core that stays tough after quench and temper (Q&T 28–32 HRC). It is the standard bar and forging stock for heavy-duty and wind-turbine gearing; annealed material is about 370 MPa yield, 640 MPa tensile, 20% elongation and 200 HB, with service to 350 °C. Case-depth control, distortion allowance and mandatory finish grinding make it costlier and longer-lead than 4140, and it has no corrosion resistance. 17CrNiMo6 or 20MnCr5 are the usual substitutes for lighter duty. 18CrNiMo7-6 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). 18CrNiMo7-6 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 70% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
What is 18CrNiMo7-6 used for?
- Wind-turbine gearbox gears
- Heavy industrial spur and helical gears
- Drive shafts and pinion shafts
- Planet carriers and planetary pinions
- Marine and rail gearbox components
- Bevel and hypoid gears
- Splined couplings
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
18CrNiMo7-6 properties
Typical room-temperature values for 18CrNiMo7-6-Annealed; bars are the position among steel grades.
Physical3
18CrNiMo7-6 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
18CrNiMo7-6 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 70% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18CrNiMo7-6 is rated for continuous service to 350°C (662 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
18CrNiMo7-6 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18CrNiMo7-6 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 35%.
Manufacturability8
18CrNiMo7-6's machinability is good (55/100, better than 62% of steel grades); weldability fair (45/100); formability fair (45/100).
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. 18CrNiMo7-6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18CrNiMo7-6
Is 18CrNiMo7-6 easy to machine?
Machine all gear geometry in the soft-annealed state (≈55% of 1212); after carburizing only grinding, honing or hard skiving with CBN is practical.
Can 18CrNiMo7-6 be welded?
Weldable only with care — preheat 200–250 °C, low-hydrogen consumables and immediate stress relief; never weld carburized surfaces.
Can 18CrNiMo7-6 be formed, bent or molded?
Hot forge at 1050–1150 °C then normalize; cold forming limited to annealed small-section bar with generous radii.
Manufacturability
The process limits FabDigit's quote engine applies to 18CrNiMo7-6. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better55 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better45 / 100 |
|---|---|
| Weldability | Better45 / 100 |
18CrNiMo7-6 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 | 0.15 – 0.21 | 0.18 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.5 – 0.9 | 0.7 |
| P | ≤ 0.03 | |
| Smax; low-S (≤0.015) variants used for wind-turbine gears | ≤ 0.04 | |
| Cr | 1.5 – 1.8 | 1.65 |
| Mo | 0.25 – 0.35 | 0.3 |
| Ni | 1.4 – 1.7 | 1.55 |
| Fe | balance |
What surface finishes work on 18CrNiMo7-6?
Not anodizable — use phosphating, black oxide, oil or Zn-Ni plating (bake to avoid hydrogen embrittlement); shot peening of tooth roots markedly raises bending fatigue life.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 18CrNiMo7-6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.658718CrNiMo7 6
- Similar grades
- 9310
How much does 18CrNiMo7-6 cost?
18CrNiMo7-6 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
18CrNiMo7-6 — frequently asked
What is 18CrNiMo7-6 used for?
18CrNiMo7-6 is typically used for wind-turbine gearbox gears, heavy industrial spur and helical gears, drive shafts and pinion shafts, planet carriers and planetary pinions, marine and rail gearbox components and bevel and hypoid gears. In short: premium gear-steel bar.
What is the yield strength of 18CrNiMo7-6?
18CrNiMo7-6 has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 18CrNiMo7-6 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine all gear geometry in the soft-annealed state (≈55% of 1212); after carburizing only grinding, honing or hard skiving with CBN is practical.
Can 18CrNiMo7-6 be welded?
With care — weldability is rated fair (45/100). Weldable only with care — preheat 200–250 °C, low-hydrogen consumables and immediate stress relief; never weld carburized surfaces.
What surface finishes work on 18CrNiMo7-6?
Not anodizable — use phosphating, black oxide, oil or Zn-Ni plating (bake to avoid hydrogen embrittlement); shot peening of tooth roots markedly raises bending fatigue life.
Can 18CrNiMo7-6 be formed, bent or molded?
Hot forge at 1050–1150 °C then normalize; cold forming limited to annealed small-section bar with generous radii.
What is the maximum service temperature of 18CrNiMo7-6?
18CrNiMo7-6 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 18CrNiMo7-6 cost?
18CrNiMo7-6 is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in 18CrNiMo7-6?
Yes — 18CrNiMo7-6 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- EN 10263-4 / EN ISO 683-3 case-hardening steel designations — CEN/ISO (2018)
- 18CrNiMo7-6 (1.6587) gear steel data sheet — Ovako / Böhler / Dörrenberg (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of gear steels) — ASM International (1991)
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.