Outer Limits 4x4 Board

I have some new OEM extractors, and want to know if they are stainless or not. They look shiney, but so does new mild steel exhaust.
any tips?

Stick a magnet on them if it drops off they're stainless

Stick a magnet on them if it drops off they're stainless

Troopy93 wrote:Stick a magnet on them if it drops off they're stainless

Yes, if it drops off it is stainless but it could still be a magnetic grade (Ferritic) of stainless (grade 409 comes to mind)
Regards Andrew.

Scrub them clean with soapy water to remove grease, then spray lightly with supersaturated salt water solution... wait 1 day. When they're all rusty, you'll know.

Try and scratch them.

awill4x4 wrote:

Troopy93 wrote:Stick a magnet on them if it drops off they're stainless

Yes, if it drops off it is stainless but it could still be a magnetic grade (Ferritic) of stainless (grade 409 comes to mind)
Regards Andrew.

Yeah true, but most system wouls likely be made out of 309 or 316 if they were to last. Just have the problem then of cracking down the track after work hardening.

Ruffy wrote:Try and scratch them.

... and ... ?

Apparently you can tell by applying a copper sulphate solution to a section of the metal. I have never tried it. The (blue) cuso4 solution turns coppery red on non-stainless, but nothing happens on stainless.

But... there are a couple of grades of stainless that give a false result.

There is another test using ferroxyl.

I've never used either of these but you might be able to find out more if you look them up.

The easiest method is to scratch one with a stainless steel ruler.

Then wet it and have a look the next day.

If they are stainless a layer of chromium oxide will form and protect from rust (it will still be shiny).

If they are mild steel a layer or iron oxide will form (rust).

It,s that simple.

Even non ferritic stainless can become magnetic if deep drawn or work hardened.

Try the magnet trick on you laundry trough at the top corner where deep drawing has occured, the magnet is likely to stick

Cheers

the simplest method would be (as already posted) lightly rub back, then spray with water, with or without salt.
Surface rust will build up within 1 day. Ive seen surface rust appear on mild steel in an hour!

chimpboy wrote:Apparently you can tell by applying a copper sulphate solution to a section of the metal. I have never tried it. The (blue) cuso4 solution turns coppery red on non-stainless, but nothing happens on stainless.
.

Yes this is correct I have used this trick at work to check if protective plating's are still on certain fasteners.

RO8M wrote:

Ruffy wrote:Try and scratch them.

... and ... ?

Mild steel is considerably softer and therefore easy to scratch.

What is the usual grade of stainless to make an exhaust system not rust on the beach
Do all grades suffer from work hardening and cracking

LuxyBoy wrote:What is the usual grade of stainless to make an exhaust system not rust on the beach
Do all grades suffer from work hardening and cracking

316L for the beach, but 304 will do.

All steel work hardens and cracks, if you have loose bits that allow vibrations you will get work hardening and cracking.

Cheers

Troopy93 wrote:

awill4x4 wrote:

Troopy93 wrote:Stick a magnet on them if it drops off they're stainless

Yes, if it drops off it is stainless but it could still be a magnetic grade (Ferritic) of stainless (grade 409 comes to mind)
Regards Andrew.

Yeah true, but most system wouls likely be made out of 309 or 316 if they were to last. Just have the problem then of cracking down the track after work hardening.

I'm sorry, but you're wrong. Most Stainless systems built by the major exhaust companies (pacemaker, HM, Lukey, DeFillipo etc) use 409 grade stainless which is an acceptable exhaust grade. HM Headers even give a 10 year warranty on them, with some exceptions of course.
Regards Andrew.

So is it worth getting a stainless system made or just save the money and replace a mild steel or aluminised one more regularly

Mild steel exhausts sound better.

Copper and titanium sound grouse. they seem to get that lovely hollow "ringing" sound.

*back to topic*

Steve.

LuxyBoy wrote:So is it worth getting a stainless system made or just save the money and replace a mild steel or aluminised one more regularly

I made 316 headers on chevy smurf, they didn't crack while I had it.

ensure the whole lot is well attached to the motor / drive line and that all tubes will expand evenly - ie don't weld a 2" long tube to the middle of a 12" tube - they will grow by different amounts when the heat up / cool down.

my whole system cost $550 inc flanges all the tube and the 21/2 for the tail pipes. this was all 316 and heaps of bends. it was a diy project though and tey are a lot of work!

so are they stainless?

j-top paj wrote:so are they stainless?

Yes we have provided umpteen ways of checking, are they stainless?