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Up Topic Welding Industry / General Welding Discussion / Copper to Steel joint
- - By Charles Francis Date 04-07-2016 13:58
Hello everyone. I have a part comprised of 3/8" thick A36 that needs to be joined to 1/8" thick 1100 copper bar. I would like to GMAW-Braze  around this joint. Can I GMAW-Braze this with a Silicon/Bronze or an Aluminum Bronze Wire ? Any recommendations on that ? Gas I am assuming to be 100% Argon or possibly a He/Ar mix because of the Copper ? Does the Copper more specifically need to be Pre-Heated ?
I also have a question should the Polarity be Electrode positive or Negative ?

Thank you in advance for the help
Parent - - By TimGary (****) Date 04-07-2016 20:03
I'm not experienced with GMAW brazing, and am hoping to learn something from your post.
Perhaps with a reply I can prime the pump a bit...

My initial thought is that you would need a nickel containing buttering layer, but that's for welding, rather than brazing.

Have you done GMAW brazing on other materials?
What code or spec are you working with?
Are you looking for structural strength, or just a seal?
Do you need to make a lot of parts, or just a single or few?
Why are you selecting GMAW braze?

Tim
Parent - By Charles Francis Date 04-07-2016 21:22 Edited 04-07-2016 21:24
Hi There and thanks for the comments. I have used ER-CuSi GMAW-arc brazing quite a bit both manually and in a robot which great success.  I only have experience using it in sheet metal assemblies where it was coated materials ( aluminized/Galv/paint Loc and others). Worked great on this stuff to eliminate burn-thru/ spatter and porosity associated with coated materials. I
With that being said, I know it can be used for dis-similar material joints . For my exact application I am not sure on the exact procedure to use ( alum bronze or Silicon Bronze ? DCEP or DCEN ?
I don't need structural strength on these. The 25-35 KSI is sufficient on these. Im choosing GMAW -Brazing over Torch Brazing  as I can use arobot for the process and I really don't have the equipment or the expertise  to Torch braze in a production environment.
Parent - - By pipewelder_1999 (****) Date 04-11-2016 02:09 Edited 04-11-2016 02:12
I have done it with GTAW and the process should also be possible with GMAW. I think Argon is suggested with DCEP. Preheat will probably be needed. Try to minimize the the amount of melting of the carbon steel to reduce dilution. ERCuSi-A is the suggested filler metal I believe. AWS Welding Handbook 3 I think has the info. Mine is at the shop but the info is in there.

Also check out Copper.org. 

You may be able to get a small quantity of filler metal and try a few things.

NOTE: The process is welding if it is done properly!
Parent - - By Charles Francis Date 04-11-2016 18:02
Thank you very much for the input !  I appreciate the comments. Glad I was thinking in the right direction.
Parent - - By Tommyjoking (****) Date 04-14-2016 04:55 Edited 04-14-2016 04:57
you can use 347 stainless for an effective tig weld.  It will be very soft of the copper side but the copper is soft anyway.  To pull it off you will naturally apply the vast majority of your heat to the copper side to wet it, then an easy skip to the a36 to pull the filler over.  I suspect that 321 or even 316 filler would have similar results.
Parent - By Lawrence (*****) Date 04-14-2016 13:05
Tommy is right...  You can easily TIG copper to steel, especially outside corner joints.  347, 321, 308, 309, 316, even Hastelloy W (wonder rod)  fillers all will do fine.   Fillets are very difficult and grooves only slightly less difficult.

But the original question mentioned "Brazing" so I was thinking about lap joints which would be much more difficult for GTAW...

However, I have used GTAW for joining stainless to copper with various brazing fillers without flux (both high and low temp), but always for argon backups and welding fixtures, and art :)  Never for any project that had an engineered load or a failure would cause problems.
Up Topic Welding Industry / General Welding Discussion / Copper to Steel joint

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