We had some horrible similar problems on some stainless steel tube
coils. Stuff looked fine when it was straight, put a bend in in it and
the grain structure made it look like a surface of an orange. Would not
pass NSF, whole batch got rejected, happened several times. Problem was
traced to a tube processor that held the tube a too high a heat for too
long, got some fairly excessive grain growth.

Koz wrote:



BIGEYE wrote:

Nobody seems to know the answer to this one.
I am considering using 6mm stainless steel as a BBQ plate. I have
heard that you can't use stainless steel for cooking food on a BBQ as
SS is full of nasties.
Can anyone confirm this?
TIA



Only one thing to watch out for. Some stainless materials (such as
T304) suffer from "green rot" (sometimes called grain rot, and something
like intergranular exfoliation--can't remember exactly) when held at 600
to 1200 degrees. The temp varies with the stainless mix so the numbers
given are for T304. 99+% of time you won't see and real problems caused
by this but it is possible that the carbides will migrate in the
stainless and you end up with large grains of material instead of a
uniform mix of metal. The result is that the stainless will become
brittle and may start corroding.

We do use T304 in roasters for vegetables at about 750 F and haven't yet
had green rot problems that caused any failures of stressed components.

They had similar problems in some military weapons of stainless where
(In pics, and I don't know squat about guns) it appeared the metal
around where the hot gasses escaped looked like it had been disolved.

To the best of my memory, the problem occurs more when held at these
temps rather than because of passing through these temps. That is, you
can run the T304 at 1300f as long as you get there fast and cool off
fast but if you let it pass slowly through the middle temps, things will
degrade.

People like the BBQ hot and a plate/skillet may be used for "blackened"
fish and similar which would require both a grate and plate to spend a
lot of time between that 600 and 1200 mark.

So...after all this blowharding...I'd still use stainless myself G

Koz