Steel 27NiCrMoV15-6 +QT900
Heat-treated state
EN 27NiCrMoV15-6
+QT900 = quenched and tempered, 900 MPa tensile class
Softer temper for very thick forgings or when maximum toughness / low-temperature impact energy is required.
Values for the +QT900 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 | — |
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 |
+QT900This page 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 +QT900?
27NiCrMoV15-6 +QT900 is 27NiCrMoV15-6 heat treated to +QT900 — softer temper for very thick forgings or when maximum toughness / low-temperature impact energy is required. 27NiCrMoV15-6 +QT900 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi). 27NiCrMoV15-6 +QT900 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; +QT900 is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 135 MPa·√m (122.9 ksi·√in), better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 800 MPa (116 ksi), better than 86% of steel grades
Limitations
- Limited formability — 18/100, worse than 84% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
27NiCrMoV15-6 +QT900 properties
Typical room-temperature values for 27NiCrMoV15-6 +QT900; 10 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 +QT900 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 +QT900 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
27NiCrMoV15-6 +QT900 is rated for continuous service to 400°C (752 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
27NiCrMoV15-6 +QT900 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 +QT900 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 +QT900's machinability is fair (43/100, worse than 71% of steel grades); weldability poor (25/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 27NiCrMoV15-6 +QT900
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 +QT900 — frequently asked
What is 27NiCrMoV15-6 +QT900 used for?
27NiCrMoV15-6 +QT900 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 +QT900?
27NiCrMoV15-6 +QT900 has a typical yield strength of 800 MPa (116 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 27NiCrMoV15-6 +QT900 easy to machine?
Not especially — machinability is rated fair (43/100, worse than 71% 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 +QT900 be welded?
Not readily — weldability is rated poor (25/100). 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 +QT900?
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 +QT900 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 +QT900?
27NiCrMoV15-6 +QT900 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.