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What’s up guys?!?! This is Michael with Michael Talks Metal back for some more nickel talk today! Before we jump in, if you find these videos useful, how about a little support for the channel and please subscribe if you haven’t already! Thank you and let’s do this!

Today we will be taking a look at one of the more popular of the Nickel alloys known as Inconel 718 when produced by Special Metals Corporation or just ” alloy 718 ” when produced by other manufacturers. The UNS chemical composition designation is N07718.

With a combination of high strength, corrosion, and oxidation resistance it has applications at temperatures ranging from minus 423 deg F to 1300 deg F.

This alloy is strengthened by a two step heat treatment:

First, the alloy is solution treated at 1700  – 1950 deg F followed by rapid cooling, usually a water quench.

Then second, the precipitation heat treatment typically consists of  heating to 1350  – 1400 deg F  for 8 to 10 hours followed by furnace cooling to 1150 – 1200 deg  F and holding for a total of 18 – 20 hours.

Applications in aerospace  include  components of rocket and jet engines and land -based gas turbines. At cryogenic temperatures it is used for tankage and other components.

With higher aging temperatures, 718 is approved for NACE oil field application.

Curie temperature is below minus 100 deg F in all conditions for non-magnetic applications.

Room temperature permeability in the aged condition is 1.0011 at 200 oersted.

Chemical composition   UNS 07718

Nickel (plus cobalt) …………………………………..   50.00  –  55.00 %

Chromium ……………………………………………….   17.00  –  21.00 %

Niobium (plus Tantalum) ……………………………    4.75  –  5.50 %

Molybdenum ……………………………………………    2.80  –  3.30 %

Aluminum ………………………………………………..    0.20  –  0.80 %

Titanium …………………………………………………..   0.65  –  1.15 %

Carbon …………………………………………………….   0.08 % maximum

Manganese ………………………………………………   0.35 % maximum

Sulfur ……………………………………………………….   0. 015 % maximum

Phosphorus……………………………………………….   0.015 % maximum

Silicon………………………………………………………    0.35 % maximum

Boron ………………………………………………………    0.006 % maximum

Iron ………………………………………………………….    Balance

Typical Room temperature mechanical properties in the treated and aged  condition:

yield strength  150,000 psi  , Tensile strength  180,000  psi , elongation 12 %

Density is  point 297 lbs per cubic inch

 

Specifications:

Bars and Forgings: 

AMS 5662, AMS 5663, AMS5664

ASTM B 637    ASME SB 637

Pipe and Tube:

AMS 5589, AMS 5590

Sheet and Plate:

AMS 5596, AMS 5597

ASTM B 670, ASTM B 906

ASME SB 670, ASME SB 906

Each specification has requirements that can add to or restrict the chemical composition beyond what we have shown you today.

Premium vacuum melting  or multiple melting cycles are often required in 718 specifications.

Heat treatment and other processing and testing requirements also exist in the individual specifications.

So to be sure that all requirements have been identified which will lead me, to tell YOU to Check the specs! Thank you for tuning in and I appreciate you watching! If you have yet to subscribe please try to do so now, if you have missed any previous videos, click here. Have a great day and see you next Thursday!