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Join Date: May 2002
Location: Up North
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304 vs 439 Stainless Steel
Hi,
Just wonder if anyone knows if 439 is better/worst material to make exhaust headers/pipes? Most commercial ones seems to use 304. Is it costs? Performance? thanks...
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted 
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04-01-2005, 11:04 AM
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MAGA
Join Date: May 2004
Posts: 10,769
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A similar arguement took place in a prvious thread. Most general aviation aircraft systems use 321 SS which is very expensive but works well when used in thin walled exhaust systems in an as welded condition.
mb911 mufflers are made of this stuff.
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German autos: '79 911 SC, '87 951, '03 330i, '08 Cayenne, '13 Cayenne 0% Liberal Men do not quit playing because they get old.... They get old because they quit playing. |
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04-01-2005, 11:12 AM
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Location: Galivants Ferry, SC
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300 series is austenitic grade...400 series is martensitic grade, although I never came across 439.....
See here for more-->http://www.sppusa.com/reference/white_paper/wp_ss.html Wil
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Wil Ferch 85 Carrera ( gone, but not forgotten ) Last edited by Wil Ferch; 04-01-2005 at 11:29 AM.. |
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04-01-2005, 11:26 AM
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Sure you did not mean 431 (martensitic grade)? 439 is a low-Ni steel similar to 430, with less Ni than 431. I imagine that 304 is better heat-resisting than 431 and 430 due to its 8% Ni content.
LeRoux
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04-01-2005, 11:37 PM
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I do know the 300 series SS has better corrosion properties than the 400. 12 years ago I built an exhaust sys for my truck with 304 SS. It is still on the truck and will probably outlive me. A friend of mine got a 409 SS exhaust for his truck. It didn't last 5 years.
Dean
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04-02-2005, 02:52 AM
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Location: Joliet, Illinois 60435
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I've seen 300 series in threaded stock, do you think or has anywone used this for exaust studs? Hope this is the correct place to ask.... gerry
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04-02-2005, 04:05 AM
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The local shop that is fabricating a straight thru pipe for me said that they are using 439 for the pipe and 304 for the flanges & mounts, etc.
Their website www.stebro.net also indicates the same. The reason he gave was 439 is softer & easier to bend. From the research I did, it does sound like its an inferior material for exhaust than 304. Should have done my research prior to getting the shop to fab that  Now I'd just hope that it will last a few years...
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
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04-02-2005, 05:49 AM
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