HAYNES® 718 alloy
Principal Features
HAYNES® 718 alloy (UNS N07718) is an age-hardenable nickel-iron-chromium-niobium (columbium)-molybdenum-titanium-aluminum alloy developed to combine excellent strength with good fabrication characteristics in the annealed condition. While limited to applications below 1200°F (650°C), it is significantly stronger at these lower temperatures than materials such as Waspaloy alloy, R-41 alloy, or X-750 alloy. It is also much easier to weld than these alloys, and is less susceptible to the strain age cracking problems common for gamma prime strengthened materials. At temperatures greater than 1200°F (650°C), 718 alloy is being replaced by HAYNES® 282® alloy due to the superior strength of 282® alloy at those temperatures as well as its excellent fabricability.
HAYNES® 718 alloy is normally only used for component applications up to 1200°F (650°C); however, its oxidation resistance is comaparable to that for other gamma-prime-strengthened superalloys.
*Please contact our technical support team if you have technical questions about this alloy.
Nominal Composition
| Weight % | |
| Nickel | 52 Balance |
| Cobalt | 1 max. |
| Iron | 19 |
| Chromium | 18 |
| Niobium* + Tantalum | 5 |
| Molybdenum | 3 |
| Manganese | 0.35 max. |
| Silicon | 0.35 max. |
| Titanium | 0.9 |
| Aluminum | 0.5 |
| Carbon | 0.05 |
| Boron | 0.004 |
*Also known as Columbium
Creep and Stress-Rupture Strengths
HAYNES® 718 Sheet, Age-Hardened*
| Temperature | Creep | Approximate Initial Stress to Produce Specified Creep in | ||||||
| 10h | 100h | 1,000h | ||||||
| °F | °C | % | ksi | MPa | ksi | MPa | ksi | MPa |
| 1000 | 538 | 0.5 | 157 | 1083 | 146 | 1007 | 132 | 910 |
| 1 | 160 | 1103 | 150 | 1034 | 138 | 952 | ||
| R | — | — | 165 | 1138 | 144 | 993 | ||
| 1100 | 593 | 0.5 | 140 | 965 | 126 | 869 | 108 | 745 |
| 1 | 143 | 986 | 130 | 896 | 112 | 772 | ||
| R | 150 | 1034 | 134 | 924 | 115 | 793 | ||
| 1200 | 649 | 0.5 | 121 | 834 | 101 | 696 | 75 | 517 |
| 1 | 124 | 855 | 103 | 710 | 78 | 538 | ||
| R | 130 | 896 | 105 | 724 | 87 | 600 | ||
| 1300 | 704 | 0.5 | 95 | 655 | 64 | 441 | 35 | 241 |
| 1 | 98 | 676 | 67 | 462 | 41 | 283 | ||
| R | 106 | 731 | 76 | 524 | 46 | 317 | ||
| 1400 | 760 | 0.5 | 54 | 372 | 24 | 165 | 3.8 | 26 |
| 1 | 60 | 414 | 28 | 193 | 5.1 | 35 | ||
| R | 70 | 483 | 37 | 255 | 17 | 117 | ||
*Samples were age hardened by treating at 1325°F (718°C)/8h/FC to 1150°F (621°C)/8h/AC
Comparison of Stress to Produce 1% Creep in 1000 Hours in Sheet
At temperatures below 1200°F (649°C), HAYNES® 718 alloy has creep strength that is superior to most other age-hardenable, wrought nickel-base superalloys. However, starting at temperatures around 1200°F (649°C) and higher, gamma-prime strengthened alloys such as HAYNES® 282® alloy, HAYNES® Waspaloy alloy, and HAYNES® 263 alloy provide higher strength.
Tensile Properties
Tensile Data, Plate
| Test Temperature | Ultimate Tensile Strength | 0.2% Yield Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 200.5 | 1382 | 167.8 | 1157 | 20.6 |
| 800 | 427 | 173.1 | 1193 | 149.0 | 1027 | 22.6 |
| 1000 | 538 | 170.2 | 1173 | 145.9 | 1006 | 21.8 |
| 1200 | 649 | 162.5 | 1120 | 139.9 | 965 | 25.1 |
| 1400 | 760 | 117.3 | 809 | 104.9 | 723 | 12.1 |
| 1600 | 871 | 42.2 | 291 | 34.3 | 236 | 68.0 |
| 1800 | 982 | 14.1 | 97 | 9.6 | 66 | 129.9 |
Mill Annealed + 1325°F/8h/Furnace Cool to 1150°F/8h/Air Cool
Total time: 18 hours
RT= Room Temperature
Tensile Data, Sheet
| Test Temperature | Ultimate Tensile Strength | 0.2% Yield Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 203.6 | 1404 | 174.7 | 1205 | 18.4 |
| 800 | 427 | 176.2 | 1215 | 155.4 | 1071 | 21.3 |
| 1000 | 538 | 172.3 | 1188 | 150.2 | 1036 | 20.7 |
| 1200 | 649 | 164.1 | 1131 | 144.3 | 995 | 16.3 |
| 1400 | 760 | 114.8 | 792 | 103.8 | 716 | 6.9 |
| 1600 | 871 | 39.9 | 275 | 34.0 | 234 | 81.8 |
| 1800 | 982 | 13.7 | 94 | 9.7 | 67 | 175.6 |
Mill Annealed + 1325°F/8h/Furnace Cool to 1150°F/8h/Air Cool
Total time: 18 hours
Physical Properties
| Physical Property | British Units | Metric Units | ||
| Density | RT |
0.297 lb/in.3 |
RT |
8.23 g/cm.3 |
| Melting Range | 2300-2435°F | – | 1260-1335°C | – |
| Electrical Resistivity | RT | 47.5 µohm.in | RT | 121 µohm.cm |
| 200°F | 48.0 µohm.in | 100°C | 122 µohm.cm | |
| 400°F | 49.4 µohm.in | 200°C | 125 µohm.cm | |
| 600°F | 50.3 µohm.in | 300°C | 127 µohm.cm | |
| 800°F | 50.7 µohm.in | 400°C | 129 µohm.cm | |
| 1000°F | 51.6 µohm.in | 500°C | 130 µohm.cm | |
| 1200°F | 52.0 µohm.in | 600°C | 132 µohm.cm | |
| 1400°F | 52.2 µohm.in | 700°C | 132 µohm.cm | |
| 1600°F | 52.1 µohm.in | 800°C | 132 µohm.cm | |
| 1800°F | 52.4 µohm.in | 900°C | 133 µohm.cm | |
| – | – | 1000°C | 133 µohm.cm | |
| Thermal Conductivity | RT |
79 Btu.in/h.ft2.°F |
RT | 11.4 W/m-°C |
| 200°F |
87 Btu.in/h.ft2.°F |
100°C | 12.6 W/m-°C | |
| 400°F |
100 Btu.in/h.ft2.°F |
200°C | 14.3 W/m-°C | |
| 600°F |
112 Btu.in/h.ft2.°F |
300°C | 15.9 W/m-°C | |
| 800°F |
124 Btu.in/h.ft2.°F |
400°C | 17.5 W/m-°C | |
| 1000°F |
136 Btu.in/h.ft2.°F |
500°C | 19.0 W/m-°C | |
| 1200°F |
148 Btu.in/h.ft2.°F |
600°C | 20.6 W/m-°C | |
| 1400°F |
161 Btu.in/h.ft2.°F |
700°C | 22.2 W/m-°C | |
| 1600°F |
173 Btu.in/h.ft2.°F |
800°C | 23.8 W/m-°C | |
| 1800°F |
186 Btu.in/h.ft2.°F |
900°C | 254.4 W/m-°C | |
| – | – | 1000°C | 27.1 W/m-°C | |
| Mean Coefficient of Thermal Expansion | 70-200°F | 7.1 µin/in-°F | 25-100°C | 12.8 µm/m-°C |
| 70-400°F | 7.5 µin/in-°F | 25-200°C | 13.5 µm/m-°C | |
| 70-600°F | 7.7 µin/in-°F | 25-300°C | 13.8 µm/m-°C | |
| 70-800°F | 7.9 µin/in-°F | 25-400°C | 14.1 µm/m-°C | |
| 70-1000°F | 8.0 µin/in-°F | 25-500°C | 14.3 µm/m-°C | |
| 70-1200°F | 8.4 µin/in-°F | 25-600°C | 14.8 µm/m-°C | |
| 70-1400°F | 8.9 µin/in-°F | 25-700°C | 15.5 µm/m-°C | |
| 70-1600°F | 9.4 µin/in-°F | 25-800°C | 16.3 µm/m-°C | |
| - | - | 25-900°C | 17.2 µm/m-°C | |
| Dynamic Modulus of Elasticity | RT |
29.0 x 106 psi |
RT | 200 GPa |
| 200°F |
28.4 x 106 psi |
100°C | 195 GPa | |
| 400°F |
27.6 x 106 psi |
200°C | 191 GPa | |
| 600°F |
26.7 x 106 psi |
300°C | 185 GPa | |
| 800°F |
25.8 x 106 psi |
400°C | 179 GPa | |
| 1000°F |
24.8 x 106 psi |
500°C | 173 GPa | |
| 1200°F |
23.7 x 106 psi |
600°C | 167 GPa | |
| 1400°F |
22.3 x 106 psi |
700°C | 159 GPa | |
| 1600°F |
20.2 x 106 psi |
800°C | 149 GPa | |
| 1800°F |
17.4 x 106 psi |
900°C | 134 GPa | |
| - | - | 1000°C | 117 GPa | |
RT= Room Temperature
Thermal Stability
Fabrication
HAYNES® 718 alloy has very good forming and welding characteristics. It may be hot-worked at temperatures in the range of about 1700-2100°F (925-1150°C) provided the entire piece is soaked for a time sufficient to bring it uniformly to temperature. Initial breakdown is normally performed at the higher end of the range, while finishing is usually done at the lower temperatures to afford grain refinement.
As a consequence of its good ductility, 718 alloy is also readily formed by cold-working. All hot- or cold-worked parts should normally be annealed at 1700 to 1850°F (925 to 1010°C) and cooled by air cool or faster rate before aging in order to develop the best balance of properties.
Tensile Properties of Solution-annealed 718 at Room Temperature
| Form | Ultimate Tensile Strength | Yield Strength | Elongation | ||
| ksi | MPa | ksi | MPa | % | |
| Sheet | 126.3 | 871 | 60.7 | 419 | 46.7 |
| Plate | 124.3 | 857 | 57.3 | 395 | 49.0 |
Cold-work Hardness
| % Cold-work | Average Hardness HRBW/ C |
| 0 | 92.4 HRBW |
| 10 | 27.2 HRC |
| 20 | 33.6 HRC |
| 30 | 36.9 HRC |
| 40 | 38.3 HRC |
| 50 | 39.2 HRC |
HRBW = Hardness Rockwell “B”, Tungsten Indentor.
HRC= Hardness Rockwell “C”.
Hardness and Grain Size
| Form | Hardness, HRBW | Typical ASTM Grain Size |
| Sheet | 94 | 6 – 8 |
| Plate | 93 | 5 – 8 |
All samples tested in solution-annealed condition.
HRBW = Hardness Rockwell “B”, Tungsten Indentor.
Welding
HAYNES® 718 alloy is readily welded by Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), Shielded Metal Arc Welding (SMAW), Electron Beam (EB) and resistance welding techniques. Its welding characteristics are similar to those for HASTELLOY® X alloy. Submerged Arc Welding (SAW) and oxyacetylene are not recommended as these processes are characterized by high heat input to the base metal and slow cooling of the weld. These factors can increase weld restraint and promote cracking.
Base Metal Preparation
The welding surface and adjacent regions should be thoroughly cleaned with an appropriate solvent prior to any welding operation. All greases, oils, cutting oils, crayon marks, machining solutions, corrosion products, paint, scale, dye penetrant solutions, and other foreign matter should be completely removed.
Filler Metal Selection
HAYNES® 718 alloy should be joined using matching filler metal (AWS A5.14 ERNiFeCr-2, AMS5832). For welding 718 alloy to other alloys, HASTELLOY® S (AMS 5838) or W (AWS A5.14 ERNiMo-3, AMS 5786) filler wires are suggested. Please click here or see the Haynes Welding SmartGuide for more information.
Preheating and Interpass Temperatures
Preheat is not required. Preheat is generally specified as room temperature (typical shop conditions). Interpass temperature should be maintained below 200°F (93°C). Auxiliary cooling methods may be used between weld passes, as needed, providing that such methods do not introduce contaminants. For further information, please click here.
Postweld Heat Treatment
HAYNES® 718 alloy is normally used in the fully-aged condition. Following forming and welding, a full solution anneal prior to aging is often employed in order to develop the best joint and overall fabrication properties. The best practice is dependent upon the specific condition of the fabrication prior to aging. Contact Haynes International, Inc. for further information.
Nominal Welding Parameters
Details for GTAW, GMAW and SMAW welding are given here. Nominal welding parameters are provided as a guide for performing typical operations and are based upon welding conditions used in our laboratories.
Specifications and Codes
Specifications
| HAYNES® 718 alloy (N07718) | |
| Sheet, Plate & Strip | AMS 5596AMS 5597SB 670 / B 670 |
| Billet, Rod & Bar | AMS 5662AMS 5663AMS 5664SB 637/B 637 |
| Coated Electrodes | – |
| Bare Welding Rods & Wire | A 5.14 (ERNiFeCr-2)AMS 5832 |
| Seamless Pipe & Tube | AMS 5589AMS 5590B 983 |
| Welded Pipe & Tube | – |
| Fittings | – |
| Forgings | AMS 5662AMS 5663AMS 5664SB 637/B 637 |
| DIN | 17742 No. 2.4668NiCr19Fe19NbMo3 |
| Others | ASME Code CaseNo.1993-6Case No. 2221-1NACE MR0175 ISO 15156 |
Codes
| HAYNES® 718 alloy (N07718) | |
| MMPDS | 6.3.5 |
Disclaimer
Haynes International makes all reasonable efforts to ensure the accuracy and correctness of the data displayed on this site but makes no representations or warranties as to the data’s accuracy, correctness or reliability. All data are for general information only and not for providing design advice. Alloy properties disclosed here are based on work conducted principally by Haynes International, Inc. and occasionally supplemented by information from the open literature and, as such, are indicative only of the results of such tests and should not be considered guaranteed maximums or minimums. It is the responsibility of the user to test specific alloys under actual service conditions to determine their suitability for a particular purpose.
For specific concentrations of elements present in a particular product and a discussion of the potential health affects thereof, refer to the Safety Data Sheets supplied by Haynes International, Inc. All trademarks are owned by Haynes International, Inc., unless otherwise indicated.
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