FYI-diff between T409/T304 stainless steel

[M1keA@aol.com]

Took this info off the NewCougar List:



From: Normand Moreau <nmoreau@videotron.ca>

I did a little search on the web for T-409 vs T-304 stainless steel.  I 
found a very simple comparative FAQ at the address : 
 http://magi.com/~andypet/sthpwc.htm

You can find a lot of detailed informations on the web about that subject. 
 This one is very concise.

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Why 409 type Stainless Steel pipes and shells?

409 type Stainless Steel is specially designed for automotive exhaust 
systems.
409 type Stainless Steel resists atmospheric and automotive exhaust gas 
corrosion.
409 type Stainless Steel developes a light surface discoloring which will 
retard progressive corrosion.
409 type Stainless Steel contains 10.5%...11.75% Chromium

Why 304(14G) type Stainless Steel tips, flanges, internals and brakets?

304 type Stainless Steel contains 18%...20% Chromium and 8%...10.5% Nickel.
304 type Stainless Steel has excellent heat, oxidation and corrosion 
resistance.
304 type Stainless Steel Looks great and will shine for ever!

How to clean Stainless Steel .

409 type Stainless Steel can be cleaned with non metallic pot scrub pads 
and soap, ammonia, liquid or powder detergent.
304 type Stainless Steel can be cleaned with non metallic non abrasive 
cleaning pads or brushes with soap or liquid detergent, use "Chrome polish" 
if necessary.

                  Do not clean with Steel Wool or a Steel Brush ---> 
surface rust will result.

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The most common stainless steel used by muffler shop is the T-409.  Borla 
use T-304 stainless steel grade.  It's why the price is so different.  A 
Borla looks great and will shine for ever!

T-409 is good for peoples who live where there are no calcium or where the 
corrosion is not a problem.
T-304 is for north american and canadian peoples who want to keep their 
cars for more than 3 years in a corrosive environment