Steel 31CrMoV9
EN 31CrMoV9
31CrMoV9 (1.8519) is a chromium-molybdenum-vanadium nitriding steel from the EN 10085 family, supplied quenched and tempered and then gas or plasma nitrided to produce a very hard, wear-resistant case on a tough core.
Values for the Q&T condition
31CrMoV9 tempers and conditions
31CrMoV9 is supplied in 7 conditions, soft to hard. Q&T is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for rough machining, deep hole drilling or forming before the final quench-and-temper cycle. | 550 | 800 | 16 | 230 HB | — |
Normalized | Intermediate mill condition for homogenising forgings and bar before final hardening; rarely a service condition. | 650 | 950 | 13 | 29 HRC | 7.8 % IACS |
+QT | Heavy forged sections for large screws/barrels where 800–1000 MPa core strength is sufficient. | 680 | 900 | 14 | 27 HRC | 7.8 % IACS |
+QT | Typical shaft/gear-blank section; slightly lower core strength due to reduced quench severity. | 780 | 1,000 | 13 | 31 HRC | 7.8 % IACS |
Q&TDefault Quenched and tempered | Standard stocked condition: oil/polymer quenched and tempered ~600–680 °C, ready for finish machining and subsequent nitriding. | 880 | 1,100 | 12 | 34 HRC | — |
gas/plasma nitrided surface (≥800 HV) | Final service condition for gears, spindles and extruder screws: hard, wear- and scuff-resistant case on a tough Q&T core with minimal distortion. | 880 | 1,100 | 11 | 65 HRC | — |
+QT | Small-diameter bar fully hardened through section — highest core strength available in this grade. | 950 | 1,150 | 10 | 38 HRC | 7.8 % IACS |
Supply forms, finishes and certifications
Ways 31CrMoV9 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Peeled/Turned Bar | +SH / peeled-turned bar in Q&T condition | Supply form |
What is 31CrMoV9?
31CrMoV9 (1.8519) is a chromium-molybdenum-vanadium nitriding steel from the EN 10085 family, supplied quenched and tempered and then gas or plasma nitrided to produce a very hard, wear-resistant case on a tough core. In the default Q&T condition it gives 880 MPa yield, 1100 MPa tensile, 12 % elongation and about 330 HB (34 HRC), with service to 450 °C; stock forms include peeled/turned bar, +A, +N and section-specific Q&T classes. Weldability is poor (0.3 % C with 2.5 % Cr), machinability is low at 40, and there is no inherent corrosion resistance. Where a through-hardening shaft steel without a nitrided case is sufficient, 34CrNiMo6 is the nearest alternative. 31CrMoV9 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). 31CrMoV9 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
What is 31CrMoV9 used for?
- Nitrided industrial shafts
- Gear surfaces
- Extruder screws and barrels
- Hydraulic piston rods
- Machine tool spindles
- Cam and control shafts
- Wear-loaded bushings and sleeves
Advantages
- High strength — 880 MPa (128 ksi), better than 89% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
31CrMoV9 properties
Typical room-temperature values for 31CrMoV9-Q&T; bars are the position among steel grades.
Physical3
31CrMoV9 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
31CrMoV9 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
31CrMoV9 is rated for continuous service to 450°C (842 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical2
31CrMoV9 has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 31CrMoV9 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability8
31CrMoV9's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (20/100); formability poor (20/100).
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. 31CrMoV9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 31CrMoV9
Is 31CrMoV9 easy to machine?
Finish machine in the Q&T state with coated carbide, ~80–140 m/min and rigid setups; leave 0.02–0.05 mm for post-nitride lapping/grinding since the nitrided case is essentially unmachinable.
Can 31CrMoV9 be welded?
Poor weldability — 0.3 %C with 2.5 %Cr; if unavoidable, preheat 300–350 °C, use matching low-hydrogen or austenitic filler and temper immediately after welding; never weld nitrided surfaces.
Can 31CrMoV9 be formed, bent or molded?
Hot forge 1050–850 °C with slow cooling, then soft anneal ~680–710 °C; cold forming is impractical above the annealed condition.
Manufacturability
The process limits FabDigit applies to 31CrMoV9. Every 31CrMoV9 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair40 / 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 | Fair20 / 100 |
|---|---|
| Weldability | Better20 / 100 |
31CrMoV9 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 | 0.27 – 0.34 | 0.31 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| P | ≤ 0.03 | |
| Smax; lower S for higher toughness/ESR grades | ≤ 0.04 | |
| Cr | 2.3 – 2.7 | 2.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| V | 0.1 – 0.2 | 0.15 |
| Fe | balance |
What surface finishes work on 31CrMoV9?
Gas or plasma nitride 500–530 °C for 0.25–0.6 mm case (≥800 HV); alternatives are oxide-black, phosphating, hard chrome or QPQ — no anodizing.
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 31CrMoV9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.8519
How much does 31CrMoV9 cost?
31CrMoV9 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
31CrMoV9 — frequently asked
What is 31CrMoV9 used for?
31CrMoV9 is typically used for nitrided industrial shafts, gear surfaces, extruder screws and barrels, hydraulic piston rods, machine tool spindles and cam and control shafts. In short: high-strength Q&T bar.
What is the yield strength of 31CrMoV9?
31CrMoV9 has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 31CrMoV9 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Finish machine in the Q&T state with coated carbide, ~80–140 m/min and rigid setups; leave 0.02–0.05 mm for post-nitride lapping/grinding since the nitrided case is essentially unmachinable.
Can 31CrMoV9 be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — 0.3 %C with 2.5 %Cr; if unavoidable, preheat 300–350 °C, use matching low-hydrogen or austenitic filler and temper immediately after welding; never weld nitrided surfaces.
What surface finishes work on 31CrMoV9?
Gas or plasma nitride 500–530 °C for 0.25–0.6 mm case (≥800 HV); alternatives are oxide-black, phosphating, hard chrome or QPQ — no anodizing.
Can 31CrMoV9 be formed, bent or molded?
Hot forge 1050–850 °C with slow cooling, then soft anneal ~680–710 °C; cold forming is impractical above the annealed condition.
What is the maximum service temperature of 31CrMoV9?
31CrMoV9 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 31CrMoV9 cost?
31CrMoV9 is a standard-cost steel ($$), 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 31CrMoV9?
Yes — 31CrMoV9 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 10085 — Nitriding steels: technical delivery conditions — CEN (2001)
- DIN 17211 (superseded) — Nitriding steels — DIN (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 (nitriding) — ASM International (2013)
- 31CrMoV9 / 1.8519 nitriding steel datasheet — Lucefin / Böhler / Dörrenberg (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.