Re: [alfa] Stainless exhaust

[bearbvd@xxxxxxxxxxxxxx (Greg Hermann)]

At 8:55 PM 1/14/04, C M Smith wrote:
>The "lower quality" stainless steel used for the guts of good exhaust
>systems is actually steel with more resistance to fatigue cracking. You
>don't want really "good" stainless steel in any environment where flexing
>is common as it turns brittle much faster than mild steel, then cracks and
>is the very devil to weld.

Pap !!

For starters--please explain why virtually all safety wire for aircraft
application IS a 300 series stainless alloy ??

BECAUSE: it doesn't strain harden NEARLY as easily as carbon or 400 series
stainless steels do !!

AND--BTW-- 321 stainless IS _THE_ best alloy for exhaust systems. PERIOD.
It is the stuff out of which things like headers and exhausts for
air-cooled aircraft piston engines are made. Going all the way back to the
REALLY big radials, such as the CW 3060.

Welding stainless is NOT all that big a trick, all you need is the correct
tools. Just as is the case if you wish to do any other job properly.
Stainless simply talks back a bit more loudly if you try to use the WRONG
tools !! (A TIG torch and an inert gas purge are the right way, aa is
filler wire of the same series of the same, or a higher numbered alloy.

Greg
>
>Actually, aluminized steel is the best stuff to make exhausts from. These
>systems last about six years under normal Canadian winters (much longer in
>warmer less salted environments) and cost less than half the cost of
>stainless. Two systems on your car last 12 years, or more (usually the
>coldest bits rust through first which are the rear mufflers) and with
>present value analysis of true costs make stainless look pretty dumb. I've
>put exactly two exhaust systems on my 91 Alfa and no more than three on my
>86 SAAB 9000 Turbo. I'm way ahead of any stainless system on a cost basis.
>
>Aluminized steel is lighter and if it cracks or spot rusts can be welded by
>incompetent buffoons at your local muffler shop and last another three
>years before  anew component might be needed.
>
>Cheers
>
>and BTW, stainless rusts alright, ocean going yachts have lost masts
>because their owners assumed stainless steel does not rust. The rigging may
>be galvanized wire but the turnbuckles will be stainless and they rust in
>the ocean environment. They just rust slowly.
>Michael Smith
>White 1991 164L
>Original owner
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