Inconel 718
Description:
Inconel 718 is a nickel-chromium-molybdenum alloy designed to resist a wide range of severely corrosive environments, pitting and crevice corrosion. This nickel steel alloy also displays exceptionally high yield, tensile, and creep-rupture properties at high temperatures. This nickel alloy is used from cryogenic temperatures up to long term service at 1200¡ã F. One of the distinguishing features of Inconel 718¡¯s composition is the addition of niobium to permit age hardening which allows annealing and welding without spontaneous hardening during heating and cooling.
The addition of niobium acts with the molybdenum to stiffen the alloy¡¯s matrix and provide high strength without a strengthening heat treatment. Other popular nickel-chromium alloys are age hardened through the addition of aluminum and titanium.
This nickel steel alloy is readily fabricated and may be welded in either the annealed or precipitation (age) hardened condition. This superalloy is used in a variety of industries such as aerospace, chemical processing, marine engineering, pollution-control equipment, and nuclear reactors.
Inconel 718 Characteristics:
Good mechanical properties ¨C tensile, fatigue and creep-rupture
Yield tensile strength, creep, and rupture strength properties are exceedingly high
Highly resistant to chloride and sulfide stress corrosion cracking
Resistant to aqueous corrosion and chloride ion stress corrosion cracking
High temperature resistant
Age-hardenable with a unique property of slow aging response that permits heating and cooling during annealing without the danger of cracking.
Excellent welding characteristics, resistant to postweld age cracking
Standards:
UNS N07718
ASTM B637, ASTM B670
AMS 5596, AMS 5662, AMS 5663, AMS 5832
ASME Case 2222-1, SFA 5.14
NACE MR0175
EN 2.4668, Werkstoff 2.4668
GE B50TF14, B50TF15
Other common names: Alloy 718, Haynes® 718, Nicrofer® 5219, Allvac® 718, Altemp® 718
Inconel 718 Chemical Composition, %
|
Ni |
50-55 |
Fe |
Remainder |
|
Cr |
17-22 |
Cu |
0.3 max |
|
Mo |
2.8-3.3 |
Nb |
4.75-5.5 |
|
C |
0.08 max |
Mn |
0.35 Max |
|
P |
0.015 max |
S |
0.015 max |
|
Si |
0.35 max |
Ti |
0.65-1.15 |
|
Al |
0.2-0.8 |
Co |
0.1 max |
|
B |
0.006 max |
|
|
Inconel 718 API Chemical Composition, %
|
Ni |
50-55 |
Cr |
17-21 |
|
Mo |
2.8-3.3 |
Mn |
0.35 max |
|
Cu |
0.23 max |
Si |
0.35 max |
|
C |
0.045 max |
S |
0.01Max |
|
P |
0.01 max |
Co |
1.0 max |
|
Cb+Ta |
4.87-5.2 |
Pb |
1000 ppm |
|
Se |
0.0005ppm |
B |
50mmpa |
|
Mg |
0.0006ppm |
Ti |
0.8-1.15 |
|
Al |
0.4-0. |
Fe |
Balance |
Mechanical Properties:
|
|
Min |
Max |
|
Ultimate tensile strength, ksi |
150 |
- |
|
0.2% yield strength, ksi |
120 |
145 |
|
Elongation, % |
20% |
- |
|
Reduction of area, % |
35% |
- |
|
Impact Strength*Min average/ min single, ft-lbs |
40/35 |
- |
|
Hardness, Rockwell C |
32 |
40 |
Inconel 718 application:
Chemical processing
Aerospace
Liquid fuel rocket motor components
Pollution-control equipment
Nuclear reactors
Cryogenic storage tanks
Valves, fasteners, springs, mandrels, tubing hangers
Well head completion equipment and blow out preventers (BOP¡¯s)
Gas turbine engine parts