Why Chrome plate Stainless Steel Motorcycle Exhaust Pipes

"How to Plate, Polish and Chrome"

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A. Never say never, Michael; everything corrodes eventually. Considering the failure rate of startups, a million mile guarantee from a startup company will unfortunately have little marketing value :-)

304 stainless steel can be nickel-chrome plated, but overall it may be no more satisfactory than nickel-chrome plated steel on the exterior. But the insides may look better and last better.

Polishing before plating would help the luster, but not as much as buffing after the copper plating and before the nickel plating.

Not being an exhaust system engineer, I know of no reason why 304 stainless can't be used, and I think it would be okay.

A. Type 316L can be polished and buffed or electropolished to look as good as chrome plating and will last a long time. If you use T304 or T316 which is not low carbon (that's what the L means) it may embrittle where it exits the head and gets very hot. Duplex nickel/chrome on mild steel can also last a very long time if properly done. Just look at Harley (factory original) chrome plating which has been done in the last 10 years.

A. Let me add my "two cents" (or would 2 dollars be more accurate nowadays?) to this discussion.

"Show Chrome" is partly as Ted says, polished copper under coat on whatever base metal you are using. As you describe your application and being a former bike owner and auto restorer as well as a plating industry supplier/technical/marketing person; I would go with the idea of 304 SS with a show quality finish (you would actually be quadruple plating, since a Woods nickel strike would be best before the copper). Marketing of the show chrome finish would probably have more appeal to buyers than a process they have not heard of (electropolishing). The use of SS will prevent (for an indeterminate period of time) rust through from inside the pipes, this is a well known fact in the auto industry as in that they switched to SS exhaust systems some years ago.
To differ with Jeff on how Harley does things: Two of my clients do outside plating for Harley (two different plants). One does steel parts, another aluminum. They both polish the acid (bright)copper then color polish the final chrome. Pre polishing of the base metal can reduce the need for some thickness of plating and the amount of later polishing. I won't get into a further technical discourse, however be advised it is not only the amount of polishing and type of plating which gives the finish, it also involves the thickness of copper and nickel applied as well as the types of chemistry used.

Duplex nickel would, in my opinion, offer no advantages in this application.

Hope this helps some.

A. I have been doing custom chrome plating for over 30 years. I have probably done thousands of exhaust pipes. Plating nickel over stainless can be done, however a good polish job and heavy nickel chrome plating on steel would be the absolute best for your application The process for plating on stainless requires two layers of nickel. In my experience I have never seen it hold on hot exhaust pipes. One good heavy nickel and chrome would be the best. I have tried copper plating on exhaust pipes before the nickel chrome and have seen it blister and peel as soon as it gets hot. So I don't recommend that either.
Just a good polish job and a heavy nickel chrome by a good plater should be all you need on exhaust pipes.
As for anything else you want to have plated make it out of steel or aluminum. Be sure and go talk to your plater about what you are trying to do. Listen to him closely and if he doesn't sound like he knows what he is doing, then go looking for someone who does. Plating is very difficult and takes years to learn. A good plater will explain what he can do and what you must do to make it work.
Good luck,

A. Why reduce reliability by introducing more opportunities for failure?
Chrome plating stainless exhausts to me is senseless.
Triple chrome plating exhausts is begging for failure.
Next you have to find a million mile motorcycle to be worth the warranty.
To my knowledge there is no such thing, and never will be if you are looking at Harley, they rank about as high in the longevity stakes as they do in the performance stakes.
Harley owners will spend their money of a well made custom system though.
There are all sorts of manufacturers and custom shops out there, custom building all manner of quality exhaust systems for every current bike out there, especially Harley.
I think I'd invest in something easier to achieve and with less competition.

A. An established manufacturer already offers a million mile guarantee on "aircraft-quality" 304 SS exhaust systems; see www.borla.com Exposed tips are mirror-polished, which minimizes corrosion and encourages owner care (& initial purchase).

To compete, offer greater value, such as 316L SS (more resistant to salty road grime) or 317L (better still).

If you wish to try plating, I suggest including a diffusion bake to prevent chipping or flaking.
Polish the 304L first, then nickel & chrome plate (with plating additives & sulfur as low as possible). Heat up fairly slowly, 2 F/min, in inert gas to 2000 F, hold a few hours, then cool (faster is OK). Polish & buff.
Details are a bit experimental; run some test specimens first.

I'm learning a lot by reading this . . . Thanks, folks! But the one thing that I strongly disagree with is discouraging people from trying to go high end in the consumer market. This is certainly the best place and perhaps the only place for money to be made today. While OEMs will beat you up on price and then replace you with a Chinese supplier without warning, consumers today have a seemingly limitless supply of cash to spend on status and high end bling. Learn how to make something truly right, so your product becomes the status symbol, and maybe you can grab a piece of the American dream.

Look at companies like Apple and Dyson ...

Better yet, look at Thule who turned the $19.95 car-top carrier and the $19.95 bicycle carrier into a $500+ high-end system and status symbol; a market they now own almost completely with limitless potential for continuing sales of very expensive specialized accessories for bikes, kayaks, skis, etc.   :-)

Find something cheap, and turn your more expensive version into a status symbol.

A. Gentlemen, I found the chrome plating of stainless line of discussion very interesting. After reading the different angles and suggestions I shared it with the people in the plant and basically decided to share our views. We are a show chrome plating company that does not discount any possibility and continues to strive for the ultimate result. Within that frame of reference, and given that with every infinite objective there is an infinite cost, we suggest to lean toward the practical. Therein on the practical side, we would suggest that chrome over highly polished stainless serves the look of chrome and provides extended value for a fair price. We are experienced at metal restoration and to save a unique stainless part, we would not use copper, and would use nickel on stainless only as a last resort. Maybe not a unique perspective but stainless like aluminum are opposite extremes on the bell curve. Stainless and Aluminum are materials not designed to be plated and if plated only achieve a marginal added value.

A. When exposed to the high heat of exhaust the copper under nickel and chrome will discolor (Blue). Pre-polish to remove metal and bending/forming flaws and Nickel-Chrome Plate. If done correctly Ni-Cr over stainless will last longer, have a deeper luster and is less labor intensive than bright buffing a formed stainless part. We have millions of stainless auto parts, both 400 and 300, over 10 years with zero rejects for corrosion or red rust.

A. I have electropolished 304 and 316 exhaust components for a big block marine engine that is moored and used in salt water since 2006. 2009 now and the parts look exactly as when they were installed:

While the components do not get as hot as auto exhaust applications as they are cooled by raw salt water injection. My point is the internal surfaces of the exhaust components have not corroded or rusted and these surfaces are in the same condition as the time of installation.
We have just mirror polished and electropolished a complete 304 s/s exhaust system for a Nissan 300ZX from the exhaust manifold flange to the tailpipe:

A. I am a corrosion specialist and car buff. There are many grades of stainless steel. Forget about plating stainless steel -- chromium plating does not have higher resistance to heat and corrosion than even low grade stainless Please ditch that whole concept OK? You want the million mile guarantee? Use Hastelloy C-276 material or Inconel 625 and polish it manually with a buffer to a mirror finish. These are the most corrosion resistant of all stainless alloys; polish to a mirror finish, and can stand 1500 degree heat. How much are your customers willing to pay?
Also, the relatively lower grades of stainless like 304LSS and 316LSS polish to a mirror finish and are more sensible for automotive exhaust systems. Most commercial aftermarket exhaust manufacturers use 304SS. After ten years, the custom 304SS exhaust on my Mercedes shows no sign of corrosion whatsoever with frequent slogging through salt infested Vermont roads. I took the tailpipes off and polished them manually -- they will go another ten years. Why would you want to plate something that polishes beautifully and is more intrinsically corrosion resistant than chromium plating? You are starting from a faulty premise.

A. Hi, David. I think the problem here is that the original question wasn't whether an owner ought to have his 316 stainless header pipes chrome plated, but how a manufacturer should try to distinguish a potential new line of super high-end pipes from his competitor's products. We received a very professional and insightful discussion by lots of very knowledgeable people :-)

Now on to your situation: I don't accept the premise that unplated 316 stainless must turn cruddy brown. I think the immediate problem is that the pipes were not passivated or, if they were, that steel wool or some other plain steel contacted them in the meanwhile; this will cause the brown rust you see, and worse. I think the right answer in your situation is to have the pipes electropolished (passivation is inherent in electropolishing). Let's see how that compares with the suggestions --

- Jeffrey Homes: it's what he suggested;
- Gene Packman: had no objection to the finish, just thought the phrase chrome plating would be more recognizable to potential buyers;
- Frank Deguire: didn't really like the idea of plating stainless;
- Steve Clark: didn't like the idea of plating stainless;
- Ken Vlach: thought unplated 316 stainless would be a good idea;
- Tracy McBride: didn't like the idea of plating stainless;
- Jim Gay: plating the stainless is good, but no copper;
- Cliff Kusch: suggested electropolishing;
- Dave Gleason: polish the stainless, don't plate it;

You'll rarely get 100% agreement in a public forum, but this was very close. Have them electropolished. Best of luck.

Regards,

A. Hi Mike. You are claiming that what David calls "cruddy brown" is the same as your "golden brown" and you might well be right! But you & I are not looking at his pipes and you might not be right; the world has acres upon acres of expensive stainless surfaces which are brown because they were not properly passivated/electropolished.
A). Stainless steel can certainly be chrome plated.
B). This page has comments from nine experienced professionals on "will it stay?" -- sorry, you & I can't herd cats nor compel professionals to completely agree; all I can say is study them and go with what you believe. Best of luck!

Regards,