Full Transcript:

What’s up guys? This is Michael with Michael Talks Metal. Talkin 347 in this video, let’s get some! Today, our video is another of the 300 series of stainless steels found in  aerospace applications……347.

Similar to 321 in chemistry and in its applications; 347 is a carbon stabilized grade using Columbium to form the carbides that might otherwise combine with Chromium and harm the corrosion performance.

Columbium …. Cb    is also known as Niobium … Nb.   Cb or Nb?  Same element with two names, not alternate alloy elements.

Type 347  is most often used in the solution annealed  condition….. aka Cond A.  Typical solution anneal is from  1850 to 2050 deg F.  Cooling rate is not critical since the Columbium precludes the formation of Chromium carbides. This allows 347 to be used at higher temperatures without the formation of grain boundary Chromium carbides that would otherwise make it susceptible to intergranular corrosion.

Like 321, this alloy can be used at temperatures up to 1500 deg F.

347 is considered non – magnetic in the annealed condition.

347            SAE 30347     UNS S34700

Density:      point 29 lbs per cubic inch

Mean Coefficient of Thermal Expansion from 32 -212 deg F:

9.2 microinch per inch per deg F

Machinability rating: 36 %   (of 1212)

Chemical Composition

Carbon            0.08 % Max

Manganese      2.00 % Max

Silicon              1.00 % Max

Phosphorus      0.04 % Max

Sulfur                0.03 % Max

Chromium        17.00 – 19.00 %

Nickel                9.00 – 12.00 %

Molybdenum     0.75 % Max

Copper              0.75 % Max

Columbium        10 x C Min – 1.10 % Max*

For example: If carbon content is .05 then Columbium minimum is 0.50% (10 x .05).  Columbium (Cb) and Niobium (Nb) are the same chemical element.

Typical  minimum mechanical properties for 347 in the solution annealed condition:

Yield Strength                30,000 psi

Tensile Strength             75,000 psi

Elongation                       35 %

Reduction of Area            50 %

Aerospace specifications for solution annealed condition:

AMS 5571 Seamless Tubing

AMS 5575  Welded Tubing

AMS 5646: Bars, Forgings, Mechanical Tubing and Rings

AMS 5512: Sheet, Strip, and Plate

AMS-QQ-S-763  Bars, Shapes, and Forgings

The ASTM and ASME standards for commercial applications are too numerous to detail here.

Refer to our website for more information and videos on stainless steels

Additional specifications and part requirements can alter what we have shown you here today. This is now the 75th time to remind you toooooo: CHECK THE SPECS !!!!!!!!!!!

Michlin Metals is a distributor and supplier of stainless steel 347. Check out website out for more info www.michlinmetals.com and if you have made it this far and haven’t subscribed click here. If you missed last weeks’ video, click here. Thanks for watching, this is Michael with Michael Talks Metal. See you next Thursday 10am! I’m out!