Steel 7CrWVMoNb9-6 CD+NT
Supply condition
EN 7CrWVMoNb9-6
CD+NT = cold drawn tube, then normalized and tempered
Small-diameter, close-tolerance superheater tubing: cold drawn for dimensional accuracy and then given the full N+T cycle to restore creep properties.
Values for the CD+NT condition
Other 7CrWVMoNb9-6 tempers and conditions
7CrWVMoNb9-6 is listed in 5 conditions; see the grade overview at 7CrWVMoNb9-6.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for bar or forging stock that will be machined or cold worked and then re-normalized and tempered before service. | 320 | 500 | 28 | 155 HB | 7.5 % IACS |
N+TDefault Normalized and tempered | Standard delivery condition for T23/P23 seamless boiler tube, pipe and plate; gives the tempered-bainite structure the creep data are based on. | 470 | 600 | 24 | 190 HB | — |
As-welded deposit | Condition of membrane-wall and superheater tube welds erected without PWHT — permitted for thin walls, but HAZ hardness and reheat-crack risk must be checked. | 480 | 620 | 18 | 29 HRC | 7.2 % IACS |
CD+NTThis page Cold drawn tube, then normalized and tempered | Small-diameter, close-tolerance superheater tubing: cold drawn for dimensional accuracy and then given the full N+T cycle to restore creep properties. | 480 | 610 | 23 | 12 HRC | 7.2 % IACS |
Quenched and tempered | Used for thick-wall headers, plate and forgings where air cooling would not give full bainite; slightly higher strength, similar creep behaviour. | 520 | 650 | 21 | 17 HRC | 7.2 % IACS |
What is 7CrWVMoNb9-6 CD+NT?
7CrWVMoNb9-6 CD+NT is 7CrWVMoNb9-6 supplied in the CD+NT condition — small-diameter, close-tolerance superheater tubing: cold drawn for dimensional accuracy and then given the full N+T cycle to restore creep properties. 7CrWVMoNb9-6 CD+NT has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 59% of steel grades. Elongation at break is 23% and the elastic modulus is 213 GPa (30.9 Msi). 7CrWVMoNb9-6 CD+NT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,465°C (2,669 °F). N+T is the default condition FabDigit quotes; CD+NT is available on request or by drawing note.
Advantages
- High service temperature — 580°C (1,076 °F), better than 97% of steel grades
- Tough — resists crack growth — 125 MPa·√m (113.8 ksi·√in), better than 85% of steel grades
Limitations
- Poor heat conductor — 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades
7CrWVMoNb9-6 CD+NT properties
Typical room-temperature values for 7CrWVMoNb9-6 CD+NT; 23 are specific to this condition. Other listed values are 7CrWVMoNb9-6 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
7CrWVMoNb9-6 CD+NT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,465°C (2,669 °F).
Mechanical16
7CrWVMoNb9-6 CD+NT has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 59% of steel grades. Elongation at break is 23% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
7CrWVMoNb9-6 CD+NT is rated for continuous service to 580°C (1,076 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
7CrWVMoNb9-6 CD+NT has an electrical resistivity of 2.4×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of 7CrWVMoNb9-6 CD+NT takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability7
7CrWVMoNb9-6 CD+NT's machinability is fair (48/100, worse than 57% of steel grades); weldability good (58/100); formability fair (38/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7CrWVMoNb9-6 CD+NT
Is 7CrWVMoNb9-6 easy to machine?
Machines like tempered-bainite 2.25Cr-1Mo at roughly half the rate of free-cutting steel; use rigid setups, coated carbide, moderate speed and generous coolant, and machine in the annealed or N+T state.
Can 7CrWVMoNb9-6 be welded?
GTAW root plus SMAW/FCAW fill with matching 2.25Cr-1.6W-V-Nb consumables; preheat 150–200 °C, control interpass below ~300 °C, PWHT 730–760 °C for thick sections (thin tubes may be left as-welded) and avoid over-restrained joints because of reheat-cracking sensitivity.
Can 7CrWVMoNb9-6 be formed, bent or molded?
Hot form at 950–1100 °C and re-normalize/temper afterwards; cold tube bending is possible on thin walls but heavy cold work must be followed by a full N+T cycle.
What surface finishes work on 7CrWVMoNb9-6?
No anodizing; protect against wet corrosion with shop primer, high-temperature aluminium paint, or diffusion coatings (aluminizing/chromizing) where steam-side oxidation limits life.
7CrWVMoNb9-6 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 | 0.04 – 0.1 | 0.07 |
| Si | ≤ 0.5 | 0.25 |
| Mn | 0.1 – 0.6 | 0.45 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cr | 1.9 – 2.6 | 2.25 |
| Mo | 0.05 – 0.3 | 0.15 |
| Wmain solid-solution strengthener | 1.45 – 1.75 | 1.6 |
| V | 0.2 – 0.3 | 0.25 |
| Nb | 0.02 – 0.08 | 0.05 |
| Bhardenability / creep | 5×10⁻⁴ – 0.01 | 0 |
| N | ≤ 0.03 | 0.01 |
| Altotal Al | ≤ 0.03 | 0.02 |
| Fe | balance | — |
7CrWVMoNb9-6 CD+NT — frequently asked
What is 7CrWVMoNb9-6 CD+NT used for?
7CrWVMoNb9-6 CD+NT is typically used for high-temperature bolts, turbine fasteners, pressure vessel components and heavy forgings. In short: creep strength to 580 °C; best-welding creep grade here; bolting-oriented Cr-W-V-Nb steel.
What is the yield strength of 7CrWVMoNb9-6 CD+NT?
7CrWVMoNb9-6 CD+NT has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 7CrWVMoNb9-6 CD+NT easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machines like tempered-bainite 2.25Cr-1Mo at roughly half the rate of free-cutting steel; use rigid setups, coated carbide, moderate speed and generous coolant, and machine in the annealed or N+T state.
Can 7CrWVMoNb9-6 CD+NT be welded?
Yes — weldability is rated good (58/100). GTAW root plus SMAW/FCAW fill with matching 2.25Cr-1.6W-V-Nb consumables; preheat 150–200 °C, control interpass below ~300 °C, PWHT 730–760 °C for thick sections (thin tubes may be left as-welded) and avoid over-restrained joints because of reheat-cracking sensitivity.
What surface finishes work on 7CrWVMoNb9-6 CD+NT?
No anodizing; protect against wet corrosion with shop primer, high-temperature aluminium paint, or diffusion coatings (aluminizing/chromizing) where steam-side oxidation limits life.
Can 7CrWVMoNb9-6 CD+NT be formed, bent or molded?
Hot form at 950–1100 °C and re-normalize/temper afterwards; cold tube bending is possible on thin walls but heavy cold work must be followed by a full N+T cycle.
What is the maximum service temperature of 7CrWVMoNb9-6 CD+NT?
7CrWVMoNb9-6 CD+NT is rated for continuous use to about 580°C (1,076 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 7CrWVMoNb9-6 N+T and 7CrWVMoNb9-6-A?
N+T is the default condition — standard delivery condition for T23/P23 seamless boiler tube, pipe and plate; gives the tempered-bainite structure the creep data are based on. A: choose for bar or forging stock that will be machined or cold worked and then re-normalized and tempered before service. Yield strength is 470 MPa in N+T versus 320 MPa in A.
Sources
- EN 10216-2 — Seamless steel tubes for pressure purposes, non-alloy and alloy steels with specified elevated temperature properties — CEN (2020)
- EN 10028-2 — Flat products of steels for pressure purposes: alloy steels with specified elevated temperature properties — CEN (2017)
- EN 10302 — Creep resisting steels, nickel and cobalt alloys — CEN (2008)
- ASTM A213/A213M Grade T23 and A335/A335M Grade P23 — ASTM International (2022)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Seamless boiler tube data for HCM2S / T23 grade — Nippon Steel / Vallourec (2020)
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.