Alloy 718, UNS N07718

Alloy 718

 

Alloy 718 (UNS N07718)

Summary

A precipitation-hardenable nickel-chromium alloy also containing significant amount of iron, niobium, and molybdenum along with lesser amounts of aluminum and titanium. It combines corrosion resistance and high strength with outstanding weldability including resistance to post weld cracking. The alloy has excellent creep-rupture strength at temperatures to 1300℉(700℃). Used in gas turbines, rocket motors, apacecraft, nuclear reactors, pumps, and tooling.

Standard Product Forms

Pipe, tube, sheet, strip, plate, round bar, flat bar, forging stock, hexagon and wire.

Chemical Composition Wt,%

 

Min

Max.

 

Min.

Max.

 

Min.

Max.

Ni

50.0

55.0

Cu

 

0.3

C

 

0.08

Cr

17.0

21.0

Co

 

1.0

Si

 

0.35

Fe

Remainder

Al

0.2

0.8

P

 

0.015

Mo

2.8

3.3

Ti

0.65

1.15

S

 

0.015

Nb

4.75

5.5

Mn

 

0.35

N

 

0.006

Physical

Constants

Density,g/ 8.19

Melting Range,℃ 1260-1336

Typical Mechanical Properties

(Solution Annealed)

(1000h) Rupture Strength (1000h) ksi Mpa

1100℉/595℃ 110 760

1200℉/650℃ 86 590

1300℉/705℃ 53 370

1400℉/760℃ 24 170

 


Microstructure

Alloy 718 is an age-hardenable austenitic material. Strength is largely dependent on the precipit prime phase during heat treatment.


Characters

Good fabricability in the annealed condition;

Good tensile, fatigue and creep-rupture strengths; at up to 700℃;

High-temperature strength up to 700℃;

Good oxidation resistance up to 1000℃;

Excellent mechanical properties in cryogenic environments;

Good weldability by arc and without susceptibility to post-weld cracking.


Corrosion Resistance

Alloy 718 has excellent corrosion resistance to many media. This resistance, which is similar to that of other nickel-chromium alloys, is a function of its composition. Nickel contributes to corrosion resistance in many inorganic and organic, other than strongly oxidizing, compounds throughout wide ranges of acidity and alkalinity. It also is useful in combating chloride-ion stress-corrosion cracking. Chromium imparts an ability to withstand attack by oxidizing media and sulfur compounds. Molybdenum is known to contribute to resistance to pitting in many media.


Applications

Due to its high-temperature strength up to 700℃, excellent corrosion resistance and ease of fabrication Inconel 718 finds applications in many field. Initially it was used as a turbine disk material in aircraft jet engines. Here resistance to creep and stress rupture eas most important. Because of its properties, fabricability and cost effectiveness it has since gained wider acceptance. Today applications vary from highly stressed rotating and static components in gas turbines and rocket engines to high-strength bolting, spring and fasteners, components in nuclear reactors and space vehicles as well as high-temperature tooling for extrusion, of for example copper, and shearing. Another more recent important application involves pump shafts and other highly stressed well head and downhole components in offshore Particularly useful is the alloy for drilling equipment in sour (containing H2S, CO2 and chlorides) oil and gas wells.


We have products:

seamless pipe,seamless tube,

 

 

 

 

 

welded pipe,welded tube,

pipe fitting,flange,bar,plate


Complete inspection equipment and quality system.
Eddy current test, Ultrasonic detector, hydraulic test equipment, Universal testing machine, Arldirect-reading spectrometer...... Recently we have replaced a new set of advanced PMI equipment, OXFORD INSTRUMENTS X-MET7000
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Advanced equipment and technological process.
We have 5 bright annealed furnace with 30 mtrs in length, the highest temperature can reach 1350℃, and the tolerance between the set and real temperature could be within 2℃, and it ensures the mechanical properities and the quality of the pipe surface.
Straightening Machine, this equipment can ensure the straightness of our big OD pipes
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