Date:         Wed, 30 Dec 1998 20:22:02 EST
Reply-To:     PaoloD1455@AOL.COM
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Paolo Damiani <PaoloD1455@AOL.COM>
Subject:      Re: How to tell if it is stainless steel pipe? (careful,
              I'm technobabbling)
Comments: To: vanagon@vanagon.com
Content-type: text/plain; charset=US-ASCII

Martin,

If it's at all magnetic, it's not a 300 series stainless. 300 series SSs are
austenitic and therefore non-magnetic. Ferritic or duplex SSs are magnetic.
Generally speaking the austenitic steels (300 series) have superior corrosion
resistance to the others.

I have seen welded 300 series SSs show some mild magnetic properties, but this
is usually due to no or poor heat treating after the welding. These areas tend
to be more susceptible to corrosion because of this loss of austenite and
formation of HAZ.

[Technobabble start]

There are "acid test" kits out there to determine alloys.  I'm not sure if
it's worth the trouble.  Alternatively, if you have a friend at a university
or in industry with access to analytical equipment, you might get be able to
get a "freebie".

I would suggest taking a sliver or filings (done with a CLEAN file) of the
stuff, find someone at Yale (material science, physics or chemistry depts) who
has a scanning electron microscope with ED Spectrometer capability (pretty
common instrument) and have them run an EDS analysis.

Make sure they run it at least 30 kV.  You should a fairly good "semi-
quantitative" analysis in about 15 minutes.  Compare the elemental percentages
to known alloys and you'll have a good idea of what you have.  Narrowing it
down is a bit more involved.

[Technobabble End]

Let me know how it works out.

Paul
89 Vanagon Carat awaiting heart transplant...

In a message dated 12/30/98 6:08:10 PM Eastern Standard Time, jag@CS.YALE.EDU
writes:

<< I just bought some Dynomax 2 1/2 tubing to use with the new
 downpipe (describer in a previous post) in a free flow exhaust.

 The catalog said it was stainless steel pipe, but when it
 arrived it looked just like regular aluminized stuff. The
 tubing has that "metal flake" look. Only difference from
 aluminized is that it is perhaps a tiny bit darker.
 The grade of SS was not specified. It doesn't look at all like
 polished T304. It's magnetic, but some SS is.

 I was majorly P'ed and was going to refuse it but the guy
 who ordered it for me called Dynomax and they maintained that it
 is indeed SS steel. Do you think I'm just getting BS'ed?

 The mandrel bending was quite nice and smooth, but the dimensions
 were not exactly as specified. Bend diameter was about 1" off.
 I think it will still work dimensionwise though.

 Thanks for any insights,
 Martin

  >>