Alloy 718 Pipe/Tube, Flanges, Fittings

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 Alloy 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:

ASTM B983 Alloy 718 / UNS N07718 Nickel Alloy Seamless Tube; Bright Annealed Nickel Alloy Tube , ISO 9001 / PED , ANSI B36.19 ASTM B829 / ASME SB829 , ASTM B167 , ASTM B444; ASTM B366 Alloy 625 / UNS N06625 Nickel Alloy 45 / 90 Degree Elbow; Alloy 625 / UNS N06625 Nickel Alloy Welded Fitting, Elbow, Tee, Reducer; ASTM B670 Alloy 718 / N07718 Nickel Allloy Sheet / Strip; ASTM B443 / ASME SB443 Alloy 625 Nickel Alloy Sheet For Oil Industry; Alloy 601 / 625 / 718 Class300 Nickel Alloy Socket Welding Flange For Medical Tube; Alloy 825 / 718 Nickel Alloy Steel Sheet For Gas And Oil Industry; ASTM B443 Alloy 625 Nickel Alloy Steel Round Rod / Bar For Oil Industry; Alloy 601 / 617 Nickel Alloy Steel Square Rod / Bar, ASTM B166 For Chemical Industry; Petroleum Refining Used S31803/32750 Heat Exchanger Tube;
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