A while back we had a thread going about whether or not the Dynomax Stainless
Steel U-Bend which Martin Jagersand purchased was indeed stainless steel.

Martin sent me some filings from the tubing and I ran an EDX (Energy
Dispersive X-ray Spectroscopy) analysis on it and some filings off the muffler
tube to compare.

The results are:

The 42322 Tubing (the tubing under suspicion) shows up as 100% iron.  This is
not true, but due to the limitations of EDX, carbon cannot be reliably
quantified.  However EDX is sensitive to all the alloying metals which make up
SS.  This tube is a plain carbon steel (and I mean very plain: no manganese,
silicon or other goodies usually thrown in to spice up carbon steel at a
moderate cost).  This explains why the tube is magnetic.

The 17263 Tubing (stuff off the muffler) looks like a 400 series (martensitic)
stainless steel.  These steels generally have decent corrosion resistance and
very good strength properties.  They are magnetic.  The nominal composition as
determined by EDX is:

Approx.:
87.5 % Iron
11.5% Chromium
.9% Silicon
.4% Manganese
and some undetermined % Carbon

Tubing 1 is not stainless steel
Tubing 2 is a martensitic stainless steel

Anyone who is a steel master and wishes to refine, improve or correct my
answer, please do.  I spent most of my material science days in 4130 steel,
316 stainless and 6000 series aluminum.  A complete command of steels in one
person is rare.

Paul 89 Carat
Very close to a decision on a Eurospec or Audi transplant