Stainless downpipes

[Flipfly]

Hi peeps, just seen the post and might be able to help. There are many different grades of Stainless Steel (and brass and steel). It's all to do with the chemical composition of the material. Stainless steel is a self healing material that when it corrodes it creates a clear seal between the base metal and the atmosphere. Austenitic stainless is what you peeps would consider to be Stainless as it does not tarnish with red rust (unless subjected to very high temperature when Martensite is formed (changes the make up of the steel effectively hardening it but reducing it's none tarnishing properties). Bored yet?
If your pipes are non magnetic they will be an Austenitic grade. If they are magnetic they will be similar to a 410/416 grade which is a hardened stainless steel (knives and forks are made of a similar grade). These grades contain a higher carbon content and are hardened. The carbon content,lower chromium and molybedenum content, along with the martensite formed during hardening is what causes the red rust. The reason you can eventually get them clean is because they are stainless. Tarnishing will happen no matter what. Try and chrome them, then you have the problems of the chrome plate flaking and looking worse.
I hope this helps. It's a laymans version but it'll give you an insite as to the choices in different materials that the designers have. Trust me these guys know more than we do!!!

 

[blues n twos]

I did mine a while back with a drill and mop fitted. Lubed the mop with Autosolve and got to work.

They came up a treat not perfect but a good shine. The tops of the downpipes go a bit brown and blue but the rest has stayed very shiney.

About once every couple of months I polish them up by hand with some wire wool and Autosolve and then a cloth.

See pic below for finished product

Jon

 

[pomm001]

Well I'm certainly no metallurgist but as as far as I can ascertain, the name Stainless isn't accurate. To make it truely 'stainless' they'd have to add so much nickle that it would be more nickle than steel.


This seems to be getting 'heated' excuse the pun.
The term 'stainless' is a generic term; there are many grades available some grades have iron content sufficiently high to be magnetic
Who’s 'stainless' is better than somebody else’s is not a valid argument.
One of the negative properties of stainless is that it is not ductile, so a balance between being able to form pipes and achieving a decent finish is the only denominator, oh almost forgot cost!

As far as resistance to discolouration both will react the same if exposed to the same temperature

I have material charts with pictures showing a relationship between stainless and exposure to temperature over time, a very long story short, the higher the temperature exposure the dirtier brown the colour goes, with a tinge of blue, then to straw at the end.

All in all it’s not the best choice for exhaust, heavy, brittle, expensive but it doesn’t rot through, and you can bring it up like new after years of abuse relatively easy
If you want looks then titanium, as Honda use on their blade
Or a double skin system, mild steel inner with chrome outer would do the job

 

[northengit]

oops I seem to have caused a bit of a rumpus

I thought that my downpipes were chrome ( an easy mistake to make) and was after some aftermarket Stainless ones to replace the OE.
I would still like to find some replacements if anyone knows of any.

keep up the healthy discussion though.


Sorry to have caused any trouble

Just to put a bit of extra fuel on the fire then.......Has anybody used/found a good high temp paint that will stay on the pipes or has any body had theirs chemicaly blacked.??? just asking.

 

[panterg]

downpipes

Hi ,just to through in my "twopenneth" does any one know if it was an old wives tale that wrapping copper wire from an exhaust stud and looping it round the downpipe would stop "blueing" a la 70's B*W ?Glenn

 

[panterg]

downpipes

Hi ,just to throw in my "twopenneth" does any one know if it was an old wives tale that wrapping copper wire from an exhaust stud and looping it round the downpipe would stop "blueing" a la 70's B*W ?Glenn