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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