Physical properties
| Density | 8.2 | g/cm³ |
| Modulus E | 199 | GPa |
| Thermal conductivity | 13 | W/(m·K) |
| Thermal expansion | 13.4 | ×10⁻⁶/K |
| Specific heat | 0.44 | kJ/(kg·K) |
| Resistivity | 1.23 | Ω·mm²/m |
Informative values: they vary with composition, condition and test method. Use the governing standard or measured mill data for pressure and heat-transfer calculations.
Chemical composition
Nominal: mid-range where both limits are given, the cap where only a maximum is, balance takes the remainder. Exact specified ranges below.
| Element | Name | Content % | |
|---|---|---|---|
| Main elements7 elements | |||
| Ni | Nickel | 50 – 55% | |
| Cr | Chromium | 17 – 21% | |
| Fe | Iron | Bal. | |
| Nb | Niobium | 4.75 – 5.5% | |
| Mo | Molybdenum | 2.8 – 3.3% | |
| Ti | Titanium | 0.65 – 1.15% | |
| Al | Aluminium | 0.2 – 0.8% | |
| Element | Name | Content % | |
|---|---|---|---|
| Minor & residual8 elements | |||
| C | Carbon | ≤ 0.08% | |
| Co | Cobalt | ≤ 1% | |
| B | Boron | ≤ 0.006% | |
| Cu | Copper | ≤ 0.3% | |
| Mn | Manganese | ≤ 0.35% | |
| Si | Silicon | ≤ 0.35% | |
| P | Phosphorus | ≤ 0.015% | |
| S | Sulphur | ≤ 0.015% | |
Mechanical minima by form
Guaranteed values differ by form, size and delivery condition; quotations confirm the specification, form, size and condition.
| Form | Condition | Rm MPa | Rp0.2 MPa | A ≥ % | Other requirements and notes |
|---|---|---|---|---|---|
| Bar and forgings | |||||
| Bar and forgings | Solution + precipitation hardened (standard heat treatment) | ≥ 1275 (185 ksi) | ≥ 1034 (150 ksi) | ≥ 12 | Also specified: Reduction of area Z ≥ 15 % · Hardness ≥ 331 HBW Also reduction of area ≥15% and hardness ≥331 HB. Supplied cold-worked or solution-annealed unless specified; listed values apply after ageing. |
| Large disk forgings / heavy rings (tangential or radial specimens) | Solution + precipitation hardened | ≥ 1275 (185 ksi) | ≥ 1034 (150 ksi) | ≥ 6 | Also specified: Reduction of area Z ≥ 8 % · Hardness ≥ 331 HBW Tangential specimens from large disk centres and radial specimens from heavy rings: elongation ≥6%, reduction of area ≥8%. |
| Bar, forgings and rings (longitudinal specimen, ≤254 mm) | Solution treated and aged, supplied in the aged condition | ≥ 1276 (185 ksi) | ≥ 1034 (150 ksi) | ≥ 12 | Also reduction of area ≥15%; supplied aged. |
| Forgings (long-transverse specimen, ≤127 mm) | Solution treated and aged | ≥ 1241 (180 ksi) | ≥ 1034 (150 ksi) | ≥ 10 | |
| Bar (transverse specimen, ≤127 mm) | Solution treated and aged | ≥ 1241 (180 ksi) | ≥ 1034 (150 ksi) | ≥ 6 | Also reduction of area ≥8%. |
| Bar, forgings and rings (longitudinal specimen, ≤127 mm) | Solution treated and aged, tensile at 649 °C | ≥ 1000 (145 ksi) | ≥ 862 (125 ksi) | ≥ 12 | Guaranteed values at 649 °C (1200 °F). |
| Bar, forgings and rings (response to heat treatment) | Supplied solution treated; must meet these after the buyer ages it | ≥ 1276 (185 ksi) | ≥ 1034 (150 ksi) | ≥ 12 | Supplied solution-treated; listed values apply after ageing. |
| Plate, sheet and strip | |||||
| Plate, sheet and strip (≤25.4 mm) | After ageing (718 °C×8 h → furnace cool to 621 °C, 18 h total) | ≥ 1241 (180 ksi) | ≥ 1034 (150 ksi) | ≥ 12 | Supplied annealed; listed values apply after precipitation treatment. |
| Plate, sheet and strip (25.4–57.2 mm) | After ageing | ≥ 1241 (180 ksi) | ≥ 1034 (150 ksi) | ≥ 10 | |
| Sheet, strip and plate (0.25–25.4 mm) | After ageing (760 °C×10 h → furnace cool to 649 °C, 20 h total) | ≥ 1241 (180 ksi) | ≥ 1034 (150 ksi) | ≥ 15 | Also specified: Hardness ≥ 38 HRC Hardness ≥38 HRC, with no rejection on hardness when tensile is acceptable. |
| Sheet, strip and plate (as solution heat treated) | Solution treated — these are UPPER limits | ≤ 965 (140 ksi) | ≤ 517 (75 ksi) | ≥ 30 | Tensile and yield are maxima (solution-treated, soft); hardness 25 HRC max recommended. |
| Tube and pipe | |||||
| High-strength seamless tube | Solution annealed + precipitation hardened (774–802 °C, 6–8 h, single step) | ≥ 1034 (150 ksi) | ≥ 862 (125 ksi) | ≥ 20 | Also specified: Hardness ≤ 40 HRC Single-step age at 774–802 °C; hardness ≤40 HRC. |
| Seamless tubing (aerospace) | As solution heat treated: 941–996 °C (±14 °C), air cooled or faster | ≤ 1069 | ≤ 655 | ≥ 30 | Tensile and yield are maxima (solution-treated, soft). Grain size ASTM 5 or finer. Flaring test to 1.20 × OD. |
| Seamless tubing (aerospace) — heat-treatment response | 718 °C ±8 for 8 h, furnace cool to 621 °C ±8, total precipitation time 18 h, air cool or faster | ≥ 1276 (185 ksi) | ≥ 1034 (150 ksi) | ≥ 12 | Also specified: Hardness ≥ 36 HRC · Rapid life ≥ 23 h @ 704 °C Values after the purchaser ages the material, not as delivered. Hardness ≥36 HRC, with no rejection on hardness when tensile is acceptable. Stress rupture at 704 °C / 500 MPa: no rupture within 23 h. |
| Seamless tubing (aerospace) | As solution heat treated: cold drawn and solution treated (no schedule specified; 1066 °C ±14 for not more than 30 min is recommended) | ≤ 1000 | ≤ 586 | ≥ 30 | Tensile and yield are maxima. Grain size ASTM 3 or finer. Flaring test to 1.25 × OD. Ultrasonic or eddy-current inspection required. |
| Seamless tubing (aerospace) — heat-treatment response | 760 °C ±8 for 10 h, furnace cool to 649 °C ±8, total precipitation time 20 h, air cool or faster | ≥ 1172 (170 ksi) | ≥ 1000 (145 ksi) | ≥ 15 | Also specified: Hardness ≥ 36 HRC Values after the purchaser ages the material, not as delivered. Hardness ≥36 HRC. |
| Several forms | |||||
| Long products ≤160 mm and flat products ≤20 mm (EN 10302, 2.4668) | +P (precipitation hardened) | ≥ 1230 | ≥ 1030 | ≥ 12 | Flat products under 3 mm: A five points lower. |
Hardness requirement
Required by the standard — ≥ 331 HB (36 HRC min)
A minimum, guarding against under-ageing — the opposite direction to the ceilings on 725 and 925. 718 is at risk from insufficient ageing; 725 and 925 are at risk from being too hard.
Creep behaviour
Guidance values (MPa) — Mean values of a scatter band. They are neither an acceptance requirement nor a design allowable stress. Figures in parentheses are long-term extrapolations and less reliable than the tested range.
| Temp °C | Creep strength Rp1.0 (1% plastic strain) | Rupture strength Ru | ||
|---|---|---|---|---|
| 10 000 h | 100 000 h | 10 000 h | 100 000 h | |
| 500 | 957 | 867 | 940 | 860 |
| 550 | 783 | 643 | 810 | 673 |
| 600 | 580 | 430 | 620 | 505 |
| 650 | 370 | 240 | 425 | 290 |
| 700 | 200 | 88 | 248 | 132 |
| 750 | 70 | 23 | 125 | 44 |
| 800 | 19 | 6.1 | 36 | 12 |
A stress-rupture acceptance requirement also applies; see "Stress-rupture requirement" below. That is a pass/fail acceptance test, quite unlike the informative guidance values in this section.
Thermal expansion and elastic modulus
| Temperature range | Mean coefficient ×10⁻⁶/K |
|---|---|
| 20–200 °C | 13.4 |
| 20–300 °C | 13.8 |
| 20–400 °C | 14.1 |
| 20–600 °C | 14.7 |
| 20–800 °C | 16.4 |
Elastic modulus vs temperature
| Temp °C | E GPa |
|---|---|
| 20 | 199 |
| 100 | 195 |
| 200 | 190 |
| 300 | 185 |
| 400 | 179 |
| 500 | 174 |
| 600 | 167 |
| 700 | 163 |
| 800 | 149 |
| 900 | 134 |
| 1000 | 120 |
| 1100 | 100 |
Stress-rupture requirement
| Heat treatment | Solution + precipitation hardened |
| Test temperature | 1200 °F (649 °C) |
| Test stress | 100 000 psi (690 MPa) |
| Minimum life | ≥ 23 h |
| Elongation | ≥ 5 % |
This is a pass/fail acceptance test, not a design creep curve.
Where this grade is recommended
Matched in 14 service conditions; ranks and scores computed from the condition-scoring matrix.
| Service condition | Industry | Temperature | Rank | Score |
|---|---|---|---|---|
| Turbo & hot fasteners | Automotive & Racing | 600 – 850 °C | 1 / 4 | 93 |
| HS fasteners & shafts | Aerospace | 300 – 650 °C | 2 / 9 | 91 |
| Drill string & non-mag collars | Oil & Gas | ≤ 150 °C | 2 / 6 | 90 |
| HT fasteners & springs | Power & Nuclear | 400 – 650 °C | 2 / 7 | 90 |
| Engine hot section | Aerospace | 650 – 900 °C | 2 / 9 | 90 |
| Turbine discs & blades | Aerospace | 600 – 800 °C | 3 / 8 | 89 |
| HT bolting & seal rings | Aerospace | 400 – 650 °C | 3 / 6 | 89 |
| Packers & downhole tools | Oil & Gas | ≤ 150 °C | 5 / 7 | 89 |
| HPHT wells | Oil & Gas | 150 – 230 °C | 5 / 7 | 88 |
| High-pressure hydrogen | Hydrogen & New Energy | ≤ 80 °C | 4 / 4 | 84 |
| Shafts, fasteners & propulsion | Marine & Offshore | 40 – 90 °C | 5 / 7 | 84 |
| Wellhead & Christmas tree | Oil & Gas | ≤ 120 °C | 7 / 7 | 84 |
Top 12 by score shown; 2 more matched conditions — browse them by industry in the selector. Open the selector →
Designations & equivalents
| UNS | N07718 / N07719 |
| W.Nr. (Germany) | 2.4668 |
| EN designation | NiCr19Fe19Nb5Mo3 |
| Trade name(s) | Inconel 718 / Nicrofer 5219 / Haynes 718 |
| ASTM / AISI | B637 / B670 / B906 / B983 |
| AMS (SAE aerospace) | 5383 / 5589 / 5590 / 5596 / 5597 / 5662 / 5663 / 5664 / 5832 / 5914 / 5950 / 5962 |
| NACE sour service | ISO 15156-3: solution-annealed and aged ≤40 HRC; API 6ACRA 140K/150K up to 44/45 HRC |
| JIS (Japan) | NCF718 |
Cross-references are common near-equivalents for search and shortlisting; substitution across standards requires clause-by-clause verification. All grades in one cross-reference table →
Applicable standards
9 specifications. Name the standard and its edition on the order.
Guaranteed values and required tests differ between specifications — see Mechanical minima by form for the figures per form.
Frequently asked questions
What is Alloy 718 (GH4169) · UNS N07718?
Alloy 718 (GH4169) · UNS N07718 — Ni superalloys. Precipitation-hardened general workhorse — aerospace and oil & gas, 650 °C class
What is the maximum service temperature of N07718?
Typically about 650 °C; the practical limit depends on media, stress and design life — acceptance per the governing standard.
What is the tensile strength of N07718?
The specified minimum tensile strength is 1275 MPa for the main product form. Minima for other forms and sizes are listed under "Mechanical minima by form" on this page.
Which standards cover N07718?
ASTM B637, ASTM B670, ASTM B983, AMS 5662, AMS 5663, AMS 5664, AMS 5596, AMS 5597, EN 10302 (creep-resisting steels, nickel and cobalt alloys)
Where is N07718 typically used?
Turbo & hot fasteners (Automotive & Racing); HS fasteners & shafts (Aerospace); Drill string & non-mag collars (Oil & Gas); HT fasteners & springs (Power & Nuclear)
In which forms is N07718 available?
Tube, plate, strip, bar, forgings, wire and other forms — sizes and delivery condition confirmed per order, with EN 10204 3.1 / 3.2 certification.
Same series
Download PDF datasheet
This grade’s datasheet as an A4 PDF — for filing, printing or forwarding to colleagues.
Download PDF datasheetSupply & enquiry
Tube & pipeφ1 – 219 × 0.25 – 25 mm
Plate4.76 – 80 mm
Barφ8 – 300 mm
Wire & filler metalsφ0.01 – 8 mmFor this grade we can supply, against your service conditions:
- Tube, plate, strip, bar, forgings, wire and more — with size range and lead time
- Chemistry and mechanical test report (EN 10204 3.1 / 3.2)
- Like-for-like alternatives and selection advice
- Applicable standards and inspection scope
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