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Difference Between Mild And Stainless Steel

bygrave316

By bygrave316,
in General Automotive Discussion

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SteveL Mentor

SteveL

Posted
Posted

Cost for the most part.

Theoretically stainless steel should be more durable (ie last longer), but the grade of stainless used I've found is at the 'lower end' of the scale, as it were (ie 304.....if they used something like 316L I'd be more impressed).

Mr. Oizo Grand Master

Mr. Oizo

Posted
Posted
what if u get mild steel, and get it coated in that high temp stuff with the money u saved by not getting stainless....that'll prevent rust anyway wouldnt it?

unless you live on the beach, mild steel will last longer than you have the car for

dezz Grand Master

dezz

Posted
Posted
unless you live on the beach, mild steel will last longer than you have the car for

cool, i thought it was mainly performance based results...thats why i was gonna get stainless. and was gonna have mild steel cat back. ill probably just go all mild steel now :P and maybe get it all coated

Mr. Oizo Grand Master

Mr. Oizo

Posted
Posted
Stainless sounds different to mild too doesn't it?

stainless is louder and resonates more

mild steel has thicker walls which quiets it down

stainless steel is also prone to cracking, especially for dump/front pipes. unless you buy something good quality, which usually means it will be around double the cost of the same item in mild steel.

Coupe-This Grand Master

Coupe-This

Posted
Posted

depending what you get and what you want. 316 stainless steel is overkill on an exhaust. 316 is what we call food grade stainless steel, we make benches and anything that comes into contact with food out of 316. why do you want a food grade exhaust system will you be eating off the muffler tip?

304 isnt as good as 316, but look at the price tag. hehe, 304 is good enough for an exhaust system. wont rust, well it can, depends on the conditions, anything metal can rust.

if you want to talk about shit stainless steel then talk about the 4xx series stainless where you can stick magnets onto it. Like what they make those stainless steel fridges and appliances out of. Thats shit quality stainless, and is mainly stainless in its appearance. As people have said stainless flows slightly better, drones, resonates more.

people also tend to forget, stainless doesnt get as soft and expand and contract as much as steell either. Any capable workshop should be able todo the same with stainless as they can with steel. Its just easier with steel. I would pick stainless, im making my exhaust for the munro out of stainless steel. Will look awesome from under the car, and just easier. You can purchase seperate bends for them, unlike steel where u have to get a shop to literally make you some 45 and 90 degree bends.

One thing i advise people not to do. Mix and match. The two steels will react with each other (electrolisis) and cause rust to begin.

Oh and i know, i work with the stuff :P

Coupe-This Grand Master

Coupe-This

Posted
Posted

i think most exhast shops will do stainless steel, best bet would to be ring around first. Try and find an exhaust shop that specialises in stainless steel exhaust systems, as specialists usually do better custom work with the specified material as they are better setup for it

djr81 Grand Master

djr81

Posted
Posted
depending what you get and what you want.  316 stainless steel is overkill on an exhaust.  316 is what we call food grade stainless steel, we make benches and anything that comes into contact with food out of 316.  why do you want a food grade exhaust system will you be eating off the muffler tip?

304 isnt as good as 316, but look at the price tag. hehe, 304 is good enough for an exhaust system.  wont rust, well it can, depends on the conditions, anything metal can rust.

if you want to talk about shit stainless steel then talk about the 4xx series stainless where you can stick magnets onto it.  Like what they make those stainless steel fridges and appliances out of.  Thats shit quality stainless, and is mainly stainless in its appearance.  As people have said stainless flows slightly better, drones, resonates more.

people also tend to forget, stainless doesnt get as soft and expand and contract as much as steell either.  Any capable workshop should be able todo the same with stainless as they can with steel.  Its just easier with steel.  I would pick stainless, im making my exhaust for the munro out of stainless steel.  Will look awesome from under the car, and just easier.  You can purchase seperate bends for them, unlike steel where u have to get a shop to literally make you some 45 and 90 degree bends.

One thing i advise people not to do.  Mix and match.  The two steels will react with each other (electrolisis) and cause rust to begin.

Oh and i know, i work with the stuff :)

A couple of things:

One of the principal differences between stainless steels & carbon (ordinary) steels is that stainless has a much higher coefficient of thermal expansion. Hence when heated it will expand much more than ordinary steel. That is why keeping the stuff flat when welding it is so difficult. It is for this reason that you should make the flanges that attach to the turbo from carbon steel - otherwise you can stress the housing. I have a set of HKS dumps made with carbon steel flanges & stainless pipes.

As for the grade 304 is just as good in this application as 316. 316 has a higher chrome content & is better at handling acids (Principally hydrochloric) - not a concern in out application. No point using either 316L or 304L as these only have a lower carbon content - a waste of money for our application.

Electrolisis can be a problem - but usually only if you live to about 140. There are that many different steels, aluminium & other metals in the engine bay it is usually not worth worrying about. :blink:

SteveL Mentor

SteveL

Posted
Posted
stainless doesnt get as soft and expand and contract as much as steell either.

I could pick on so much in your post, but lets stick with this. Stainless steel can be annealed like any other steel and it actually has about twice the thermal expansion rate of carbon steel.

Oh and i know, i work with the stuff :)

I'm a metallurgist by profession with, well, let's just say many years experience including specialisation in material and welding specifications for stainless steels. You'll notice I mentioned 316L specifically - there's good reason for specifying the low carbon form when welding. If you work with it you'll know why.

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