stainless
There's all kind of stainless and some is more stainless
than others. There are tradeoffs between hardness /
material properties and corrosion resistance. I have a
stainless SLP Y-pipe and it's good and brown. Not
like regular steel crusty brown, just a discoloration.
Especially the hot part of the headers, I would expect
to see blue and straw color after the first heat cycle
and settling into a dull browned look eventually. But
this oxide will be stable and not progress at anything
like the rust rate of mild steel.
Now, you take a wire brush to it and crumbs come off,
that's not stainless.
Some stainless is nonmagnetic and the rest, fairly
weakly magnetic. So you could test by a small magnet,
judging the "stick" relative to body sheet metal.
than others. There are tradeoffs between hardness /
material properties and corrosion resistance. I have a
stainless SLP Y-pipe and it's good and brown. Not
like regular steel crusty brown, just a discoloration.
Especially the hot part of the headers, I would expect
to see blue and straw color after the first heat cycle
and settling into a dull browned look eventually. But
this oxide will be stable and not progress at anything
like the rust rate of mild steel.
Now, you take a wire brush to it and crumbs come off,
that's not stainless.
Some stainless is nonmagnetic and the rest, fairly
weakly magnetic. So you could test by a small magnet,
judging the "stick" relative to body sheet metal.
