Full Transcript:

What’s up guys?!?!?! This is Michael with Michael Talks Metal back for another stainless session. Today, our video is another of the 300 series of stainless steels found in  aerospace applications.

In our  prior videos, type 304 and 316 had low carbon versions 304L and 316L that minimized the ability of the alloy to form harmful Chromium carbides by virtue of the low carbon content.

Another way to prevent the formation of Chromium carbides, would be to add an alloying element that more readily forms carbides that would not harm the corrosion resistance.

Type 321 is an austenitic stainless steel that utilizes Titanium’s ability to form stable carbides with any carbon present. It 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 Titanium precludes the formation of Chromium carbides. This also allows 321 to be used at higher temperatures without the formation of grain boundary Chromium carbides that would otherwise make it susceptible to intergranular corrosion.

Is 321 Magnetic? 321 is considered non – magnetic in the annealed condition.

321           SAE 30321     UNS S32100

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

Titanium           6 x C Min – 0.70 % Max*

For example: If carbon content is .05 then Titanium minimum is 0.30% (6 x .05)

Typical  minimum mechanical properties for 321 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 5570 Seamless Tubing

AMS 5576  Welded Tubing

AMS 5645: Bars, Forgings, Mechanical Tubing and Rings

AMS 5510: 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. SO what am I about to say? You know it! CHECK THE SPECS !!!!!!!!!!! Check out the earlier videos on stainless steels here  and visit us at our website at www.michlinmetals.com. This is Michael with Michael talks metal, if you are still here and haven’t subscribed click here, if you missed last weeks video, click here. See you guys next Thursday 10am. I’m out.