Nickel Alloy N7M-AW (As-welded deposit)
Heat-treated state
UNS J30007, N10665 · ASTM A494 N7M
Low-carbon chemistry allows weld repair without post-weld solution treatment for many services; re-anneal if maximum HCl resistance is required.
Values for the AW condition
Other N7M tempers and conditions
N7M is listed in 4 conditions; see the grade overview at N7M.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed | Standard supply condition for all ASTM A494 N-7M castings — required for full corrosion resistance and ductility. | 310 | 585 | 30 | 187 HB | 1.3 % IACS |
hot isostatically pressed then solution annealed | For thin-wall investment-cast pump and valve parts where microporosity must be eliminated for pressure-boundary or radiographic acceptance. | 320 | 620 | 38 | 190 HB | 1.3 % IACS |
As fabricated | Only for non-corrosion structural or trial parts — interdendritic Mo segregation and carbides lower ductility and acid resistance. | 330 | 520 | 12 | 16 HRC | 1.2 % IACS |
AWThis page As-welded deposit | Low-carbon chemistry allows weld repair without post-weld solution treatment for many services; re-anneal if maximum HCl resistance is required. | 330 | 560 | 22 | 13 HRC | 1.3 % IACS |
What is N7M-AW?
N7M-AW is N7M heat treated to AW — low-carbon chemistry allows weld repair without post-weld solution treatment for many services; re-anneal if maximum HCl resistance is required. N7M-AW has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 67% of nickel alloy grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi). N7M-AW has a density of 9.22 g/cm³ (0.333 lb/in³), heavier than 97% of nickel alloy grades. It melts at 1,330°C (2,426 °F). SA is the default condition FabDigit quotes; AW is available on request or by drawing note.
Limitations
- Low electrical conductivity — 1.3 % IACS, worse than 99% of nickel alloy grades
- Limited service temperature — 425°C (797 °F), worse than 90% of nickel alloy grades
- Limited formability — 15/100, worse than 81% of nickel alloy grades
N7M-AW properties
Typical room-temperature values for N7M-AW; 23 are specific to this condition. Other listed values are N7M reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
N7M-AW has a density of 9.22 g/cm³ (0.333 lb/in³), heavier than 97% of nickel alloy grades. It melts at 1,330°C (2,426 °F).
Mechanical14
N7M-AW has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 67% of nickel alloy grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal5
N7M-AW is rated for continuous service to 425°C (797 °F). It conducts heat at 11.1 W/m·K (6.41 BTU/hr·ft·°F), worse than 54% of nickel alloy grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
N7M-AW conducts electricity at 1.3 % IACS, worse than 99% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), better than 51% of nickel alloy grades.
Sustainability4
Producing a kilogram of N7M-AW takes about 180 MJ of energy and emits 13.5 kg of CO₂ — more than 69% of nickel alloy grades. Typical recycled content is 40%.
Manufacturability8
N7M-AW's machinability is poor (20/100, better than 53% of nickel alloy grades); weldability good (65/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with N7M-AW
Is N7M easy to machine?
Slow speeds, heavy positive-rake carbide, rigid setup and flood coolant — the alloy work-hardens fast and never break the cut dwelling in one spot.
Can N7M be welded?
GTAW/GMAW with matching ENiMo-7 / ERNiMo-7 (B-2) filler, low heat input, interpass below ~100 °C; the low-carbon chemistry usually permits weld repair without re-annealing.
Can N7M be formed, bent or molded?
Sand or investment cast from vacuum/argon-protected melts; generous risering and rapid solidification are needed to limit Mo microsegregation, then solution anneal and quench.
What surface finishes work on N7M?
Pickle in HF–HNO₃ or grit-blast plus passivation to remove casting scale; mechanically polishes well, no anodizing or plating normally applied.
N7M 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 |
|---|---|---|
| Mo | 30 – 33 | 31.5 |
| Fe | ≤ 3 | 1.5 |
| Cr | ≤ 1 | 0.5 |
| C | ≤ 0.07 | 0.03 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 1 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Niremainder, typically ~65–68 % | balance | — |
N7M-AW — frequently asked
What is N7M-AW used for?
N7M-AW is typically used for hydrochloric acid pumps, chemical process valves and acid recovery equipment castings. In short: cast Hastelloy B-2 equivalent; top cast HCl resistance; non-oxidizing acid specialist.
What is the yield strength of N7M-AW?
N7M-AW has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 67% of nickel alloy grades. Strength varies by condition: see the 4 listed tempers.
Is N7M-AW easy to machine?
Not especially — machinability is rated poor (20/100, better than 53% of nickel alloy grades). Slow speeds, heavy positive-rake carbide, rigid setup and flood coolant — the alloy work-hardens fast and never break the cut dwelling in one spot.
Can N7M-AW be welded?
Yes — weldability is rated good (65/100). GTAW/GMAW with matching ENiMo-7 / ERNiMo-7 (B-2) filler, low heat input, interpass below ~100 °C; the low-carbon chemistry usually permits weld repair without re-annealing.
What surface finishes work on N7M-AW?
Pickle in HF–HNO₃ or grit-blast plus passivation to remove casting scale; mechanically polishes well, no anodizing or plating normally applied.
Can N7M-AW be formed, bent or molded?
Sand or investment cast from vacuum/argon-protected melts; generous risering and rapid solidification are needed to limit Mo microsegregation, then solution anneal and quench.
What is the maximum service temperature of N7M-AW?
N7M-AW is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between N7M-SA and N7M-F?
SA is the default condition — standard supply condition for all ASTM A494 N-7M castings — required for full corrosion resistance and ductility. F: only for non-corrosion structural or trial parts — interdendritic Mo segregation and carbides lower ductility and acid resistance. Yield strength is 310 MPa in SA versus 330 MPa in F.
Sources
- ASTM A494/A494M — Castings, Nickel and Nickel Alloy (Grade N-7M) — ASTM International (2022)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- HASTELLOY B-2 alloy (N10665) technical data — Haynes International (2020)
- Corrosion of Nickel-Base Alloys in Reducing Acids — NACE/AMPP (2018)
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.