Steel 27NiCrMoV15-6 +NT (Normalized and tempered)
Heat-treated state
EN 27NiCrMoV15-6
Used for very large or complex forgings where liquid quenching is impractical; slightly lower strength and toughness than +QT.
Values for the +NT condition
Other 27NiCrMoV15-6 tempers and conditions
27NiCrMoV15-6 is listed in 9 conditions; see the grade overview at 27NiCrMoV15-6.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose for rough machining of large forgings before final quench and temper. | 520 | 790 | 20 | 21 HRC | — |
+NTThis page Normalized and tempered | Used for very large or complex forgings where liquid quenching is impractical; slightly lower strength and toughness than +QT. | 720 | 900 | 16 | 27 HRC | 7 % IACS |
Normalized | Intermediate grain-refining step; because of the high hardenability this steel air-hardens to a hard bainitic/martensitic structure, so it is rarely a final supply condition. | 750 | 1,000 | 14 | 31 HRC | 7 % IACS |
Quenched and tempered, 900 MPa tensile class | Softer temper for very thick forgings or when maximum toughness / low-temperature impact energy is required. | 800 | 950 | 17 | 30 HRC | — |
hardness-controlled temper | Ordered when the customer specifies a hardness band for shaft/gear machining and fatigue life rather than a tensile class. | 910 | 1,060 | 15 | 34 HRC | 7 % IACS |
+QTDefault Quenched and tempered | Standard supply condition for shafts, rotors and heavy-section forgings needing high strength with good toughness. | 930 | 1,080 | 15 | 35 HRC | — |
+QT + gas/plasma nitrided surface | Pick when a hard, wear- and scuffing-resistant case with high fatigue strength is needed on a tough Q&T core (barrels, spindles, rotor journals). | 930 | 1,080 | 14 | 62 HRC | 7 % IACS |
Quenched and tempered, 1100–1300 MPa tensile class | High-strength temper for moderate sections (gun tubes, highly loaded shafts) where toughness can be traded for strength. | 1,050 | 1,200 | 12 | 39 HRC | — |
high-hardness temper | For wear-loaded and highly stressed parts machined with carbide tooling; toughness margin is reduced. | 1,090 | 1,250 | 11 | 40 HRC | 7 % IACS |
What is 27NiCrMoV15-6 +NT?
27NiCrMoV15-6 +NT is 27NiCrMoV15-6 heat treated to +NT — used for very large or complex forgings where liquid quenching is impractical; slightly lower strength and toughness than +QT. 27NiCrMoV15-6 +NT has a yield strength of 720 MPa (104 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 82% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi). 27NiCrMoV15-6 +NT 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). +QT is the default condition FabDigit quotes; +NT is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 720 MPa (104 ksi), better than 82% of steel grades
Limitations
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
27NiCrMoV15-6 +NT properties
Typical room-temperature values for 27NiCrMoV15-6 +NT; 22 are specific to this condition. Other listed values are 27NiCrMoV15-6 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
27NiCrMoV15-6 +NT 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).
Mechanical16
27NiCrMoV15-6 +NT has a yield strength of 720 MPa (104 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 82% of steel grades. Elongation at break is 16% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
27NiCrMoV15-6 +NT is rated for continuous service to 400°C (752 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
27NiCrMoV15-6 +NT conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 27NiCrMoV15-6 +NT takes about 31 MJ of energy and emits 2.3 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
27NiCrMoV15-6 +NT's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (30/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 27NiCrMoV15-6 +NT
Is 27NiCrMoV15-6 easy to machine?
Rough machine in +A condition; in Q&T (300–370 HB) use rigid setups, coated carbide, ~80–120 m/min with positive-rake inserts and flood coolant.
Can 27NiCrMoV15-6 be welded?
High carbon equivalent — preheat 200–300 °C, low-hydrogen consumables, interpass control and immediate PWHT/temper below the tempering temperature; welding of finished rotors is generally avoided.
Can 27NiCrMoV15-6 be formed, bent or molded?
Hot forge 1100–1180 °C, finish above 900 °C, slow cool or immediate anneal to avoid flaking; cold forming is not practical.
What surface finishes work on 27NiCrMoV15-6?
No natural corrosion resistance: use phosphate + oil, black oxide, zinc-nickel, hard chrome or nitriding; the clean forging structure polishes well for shaft journals and seal areas.
27NiCrMoV15-6 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 | 0.24 – 0.3 | 0.27 |
| Si | ≤ 0.3 | 0.2 |
| Mn | 0.2 – 0.5 | 0.35 |
| Pmax; low P/S for heavy forgings | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | 1.2 – 1.6 | 1.4 |
| Mo | 0.4 – 0.6 | 0.5 |
| Ni | 3.5 – 4 | 3.75 |
| V | 0.05 – 0.15 | 0.1 |
| Fe | balance | — |
27NiCrMoV15-6 +NT — frequently asked
What is 27NiCrMoV15-6 +NT used for?
27NiCrMoV15-6 +NT is typically used for turbine rotors and shafts, heavy machinery forgings, generator shaft forgings, large gearbox input shafts, nitrided shaft journals and seal areas and highly stressed coupling forgings. In short: heavy-section high-toughness forging; multiple QT strength classes; very limited weldability.
What is the yield strength of 27NiCrMoV15-6 +NT?
27NiCrMoV15-6 +NT has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 82% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 27NiCrMoV15-6 +NT easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Rough machine in +A condition; in Q&T (300–370 HB) use rigid setups, coated carbide, ~80–120 m/min with positive-rake inserts and flood coolant.
Can 27NiCrMoV15-6 +NT be welded?
Not readily — weldability is rated poor (30/100). High carbon equivalent — preheat 200–300 °C, low-hydrogen consumables, interpass control and immediate PWHT/temper below the tempering temperature; welding of finished rotors is generally avoided.
What surface finishes work on 27NiCrMoV15-6 +NT?
No natural corrosion resistance: use phosphate + oil, black oxide, zinc-nickel, hard chrome or nitriding; the clean forging structure polishes well for shaft journals and seal areas.
Can 27NiCrMoV15-6 +NT be formed, bent or molded?
Hot forge 1100–1180 °C, finish above 900 °C, slow cool or immediate anneal to avoid flaking; cold forming is not practical.
What is the maximum service temperature of 27NiCrMoV15-6 +NT?
27NiCrMoV15-6 +NT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10250-3 Open die steel forgings — Alloy special steels — CEN (1999)
- EN 10027-1/-2 Designation systems for steels (1.6957) — CEN (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Heavy forging alloy steel Ni-Cr-Mo-V datasheets (Saarschmiede / Böhler / Buderus grade sheets) — various producers (2022)
- GB/T 3077 ( 30CrNi4MoV ) — SAC (2015)
- SMM / Mysteel (2025)
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.