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Finishing stainless steel after welding

 

Is there a quick way of removing heat discoloration after welding stainless steel, without having to use scotch brite pads.

Paul Leger
- Moncton, N.B., CANADA

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Hi Paul,

Yes, there are a number of ways. The most popular is pickling using a nitric acid and hydrofluoric acid mixture which will also passivate the surface. See ASTM ASTM A380 .

There are a number of pastes which can be applied with a brush if the area to be treated is small. These can often be purchased from your local welding supplier.

Electro-polishing is another way and it also provides a nice shine to the weld at the same time as smartening up and passivating the entire weldment.

I would give you the names of some of the pastes but it is against the policy of this web site to provide endorsements. Right?

Good luck,

John Holroyd
- Elkhorn, WI

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Ed. note: We don't want to stand in the way of information transfer, John, but we discourage posting of testimonials. It isn't fair to ask our supporting advertisers pay the costs of maintaining testimonials to their competitors who bear none of the costs; further, the internet is largely anonymous and as soon as testimonials are allowed, shills follow (look how the once fabulous scichem newsgroups were destroyed by commercial postings).

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If you mean quick regarding the element of time, the answer is no using mechanical methods. Abrasive blasting might be shorter; however, your surface finish will be rougher also. You didn't mention anything about surface finish quality. Lastly, if quick means less labor intensive, the answer is yes. Most mass finishing systems will remove discoloration and provide a good finish.

AF Kenton
retired business owner - Hatboro, Pennsylvania

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From your mention of scotchbright pads, I assume you want a satin finish on your parts. There are several ways without using pads by hand. A couple methods I use are: just put whatever grit greaseless compound on a buffing wheel (it does not need to be completely dry, you can keep adding it from the tube as you work. There are also non woven nylon pads made in a similar fashion to an airway buff ⇦ this on eBay or Amazon [affil links] that can also be used. These are a couple of the easiest methods to get the discoloration out and match the existing finish if that is what you are after.

Hope this helps.

Vernon Moore
polishing - Salem, Arkansas

The best way is to just get a 6" dia Nylon mop wheel and the job will be done in a very short time. Or a surface finishing belt.

Thomas Mc Glynn
- Ireland