Preventing heat discoloration

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I am a hobbyist. Stuff I weld sometimes needs to look good (as in polished), and sometimes I polish parts of it before welding because polishing it after would be awkward. Usually I can access the weld side in order to re-finish it after welding no problem, but reaching the back side of the weld is not easy. Now, I understand that if I flood the back side with argon, it won't discolor - but I wonder if there are any other methods? Can I cover the back side with something - some high temp tape, foam, something - that would prevent oxygen from reaching it and discoloration from occurring? Have you seen something like this done?
Reply:I never thought of 02 in conjunction with the heat discoloration near a weld.  I just thought it happened, didn't wonder why.  Pretty cool stuff.  Is it some form of oxidization?"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammI never thought of 02 in conjunction with the heat discoloration near a weld.  I just thought it happened, didn't wonder why.  Pretty cool stuff.  Is it some form of oxidization?
Reply:Depending on how hot you get the back side, you might have success by painting it with waterglass (Na-silicate), an alcohol-soluble high-temp. flux, or a high-temp, high viscosity silicone oil. If you get the metal hot enough, the silicon compounds may be able to 'react with' meaning dissolve in and thus change the metal properties, while the flux may 'burn' and be ineffective.There is a commercial material made for this purpose, which contains some of these plus some fluorides, borates, etc. but I can't remember its name. Someone else here surely will before long. Maybe do a search using the word "protection" to find it.
Reply:Is what your welding flat? If you can reach the back side enough to tape it up, you probably have enough room to slide some narrow stock under the area to be welded and temporarily clamp it in place.
Reply:Ambient atmosphere is the base issue. An inert gas purge is of course the best option in terms of quality, and I've used a localized purge on many a weldment using run of the mill aluminum foil with aluminum adhesive tape. I'm not sure about your specific application though, so you'll just have to see if that works for you. Another option is a copper plate applied directly to the backside of the weld, again to eliminate exposure to atmosphere, and this with the added heat sink to counter distortion. I for one have even used regular dirt on a jobsite, just jammed up enough to back the weld. That may not be advisable, though, I think I just got lucky on that one What options have you looked into regarding oxidation treatment AFTER the weldment? There's a way to EP using a battery charger and a few chemicals that may suit your needs. Kinda noxious, though. All in all, I would say that as a hobbyist your best recourse at this point would be to purge where you can, experiment with copper backings, and only after completely exhausting those options invest capital into more specialized solutions.FIRE AND WIRE
Reply:Originally Posted by JayAmbient atmosphere is the base issue. An inert gas purge is of course the best option in terms of quality, and I've used a localized purge on many a weldment using run of the mill aluminum foil with aluminum adhesive tape. I'm not sure about your specific application though, so you'll just have to see if that works for you. Another option is a copper plate applied directly to the backside of the weld, again to eliminate exposure to atmosphere, and this with the added heat sink to counter distortion. I for one have even used regular dirt on a jobsite, just jammed up enough to back the weld. That may not be advisable, though, I think I just got lucky on that one What options have you looked into regarding oxidation treatment AFTER the weldment? There's a way to EP using a battery charger and a few chemicals that may suit your needs. Kinda noxious, though. All in all, I would say that as a hobbyist your best recourse at this point would be to purge where you can, experiment with copper backings, and only after completely exhausting those options invest capital into more specialized solutions.
Reply:we use solorflux in tha field some times you spread it on the inside instead of purging the pipe or vessel i assume your talking abt stainless it will prevent sugar but i really thank its not worth a **** if you have some one hold a hose with argon on the backside of the weld it will work much better you dont necesarrily have to flood the atmosphere just keep argon on the weld area until it cools we do this alot of times when welding on a vessel but you will need another flow meter and just the hose and set it on the same setting you set your rig on (20-40lbs)Complete Fabrication Shop specializing in pipe fabrication. Also offering heavy steel fabrication and sheet metal work.