Annealing 304 SS

[blackSVO]

I have an Exhaust manifold on an automotive application
that frequently sees temps. of 1700 degrees. I know that
this is not the best grade of material to use, but it was
what I had laying around at the time. After a period
of heat cycles the material seems to get brittle and
cracks. If I try to anneal this pc., will it help
with the longetivity of the pc.? Or, will annealing
the material not be beneficial? Is there anything that
I can do to this pc. that would help it survive these
temps?

Thanks for your help.

Steve

 

[0707]

For 1700ºF? 926ºC SS TP304 is not suitable.

If your material is already brittle and cracked the annealing will not recovery your TP304

 

[blackSVO]

What exactly is happening to the metal to make it
brittle?

Thanks Again.

Steve

 

[EdStainless]

I doubt that it is getting brittle. It is probably failing by a combination of thermal and mechanical fatigue. Often making these systems less rigid helps.

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[JamesCKelly]

Simply exposing 304, or 304L, to 1700F will not embrittle it. Is 1700F the exhaust gas temperature? In which case cooling by air on the outside might make the actual metal temperature somewhat lower than 1700F. Is this used on the road during Michigan winters? I.e.,does the metal get splashed by road salt? Chloride Stress Corrosion Cracking (SCC) from salt is a possiblility. If SCC is the problem, the cracks will often look like branched, spidery little things with a bit of rust seeping out. If it is thermal fatique the cracks may associate with a bend, a weld, or a change in section size. As EdStainless says, making the system more flexible, so that the various areas can expand and contract somewhat independently of one another helps. Often corrugated sections are used so that the metal may flex a little rather than being under high temsile load from differential thermal expansion. Tought to say without looking at it.