The Murphy Builders Site

FWIW (and it may be very litlle) I have not been able to verify actual
poor experiences with 304 stainless. Yes 321 is superior at high
temperatures and preferred. However near as I can tell 304 headers stand
up very well in normally aspirated auto racing (even when wrapped) where
it seems to be considered superior to oem 409 stainless and mild steel.
At high power, aircraft header temperatures can apparently reach the
temperature necessary for carbide formation in 304 and resultant
cracking, but at what rate and is it significant? 321 can also crack
quickly if expansion and vibration are not allowed for or if argon
purging is not used during welding. Anyway I went with 304 on my Subaru.
If nothing else I've learned a bit about working with stainless while
using the much cheaper material. Proponents of using mild steel for the
first part of the headers because "stainless will crack" don't seem to
differentiate between 321 and 304 and don't seem to recite actual
experiences so I decided to try the experiment... ;)
Ken

RJBWoodman@aol.com wrote:
snip

built from .035 304 stainless that i
have been told won't hold up for very long, heat will deteriorate it fast

Snip




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Ken,

To complicate things even more for you can buy 304 and 304L. If I remember correctly,304L is low carbon and not as susceptible to grain growth from welding and the associated potential for cracks.

Used to have a metualurgist participate in design reviews that you would swear was asleep - asleep until someone mentioned 304. He would then come alive and deliver a mini-speech on how he wouldn't approve 304 for welded parts and then on the benefits of 304L and 321.

Terry



--- klehman@albedo.net wrote:

FWIW (and it may be very litlle) I have not been able to verify actual
poor experiences with 304 stainless. Yes 321 is superior at high
temperatures and preferred. However near as I can tell 304 headers stand
up very well in normally aspirated auto racing (even when wrapped) where
it seems to be considered superior to oem 409 stainless and mild steel.
At high power, aircraft header temperatures can apparently reach the
temperature necessary for carbide formation in 304 and resultant
cracking, but at what rate and is it significant? 321 can also crack
quickly if expansion and vibration are not allowed for or if argon
purging is not used during welding. Anyway I went with 304 on my Subaru.
If nothing else I've learned a bit about working with stainless while
using the much cheaper material. Proponents of using mild steel for the
first part of the headers because "stainless will crack" don't seem to
differentiate between 321 and 304 and don't seem to recite actual
experiences so I decided to try the experiment... ;)
Ken

RJBWoodman@aol.com wrote:
snip

built from .035 304 stainless that i
have been told won't hold up for very long, heat will deteriorate it fast

Snip




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