# Stainless to copper fusion.



## COMachinist (Sep 5, 2021)

Hi All
Happy Labor Day. I have a project under way now that my knee replacement is about 3 weeks old. I can get around the shop pretty good again and can already tell I will be spending lots of time out there With out much pain.
Back to the question, I am building a project that needs some 304 stainless fusion welding to copper. It needs to be water tight, and I don’t want to spend $100.00 for a couple 18” silver brazing rod. I have a TIG setup, and have argon, will this gas work for fusion welding the to together? I saw a youtube video doing this but it did not say what gas they used. Any help is appreciate.
CH


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## Al 1 (Sep 5, 2021)

CH,     Argon  and silicon bronze.  Braze.  Al.


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## Ulma Doctor (Sep 5, 2021)

tig welding uses 100% argon as the shielding gas


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## COMachinist (Sep 6, 2021)

Ulma Doctor said:


> tig welding uses 100% argon as the shielding gas


Yeah I know, that is what I have. But you can also use helium, 80/20 helium/Argon, CO2/argon mix, Nitrogen for deep penetration. There may be more. Even thought I’m 1595 certified I don’t know every thing. Never have welded SS to copper this will be my first go around with this configuration. I have not done copper with copper filler in a long time but will give it a shot and see if it will work on SS/copper.
Thanks everyone.
CH


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## woodchucker (Sep 6, 2021)

COMachinist said:


> Yeah I know, that is what I have. But you can also use helium, 80/20 helium/Argon, CO2/argon mix, Nitrogen for deep penetration. There may be more. Even thought I’m 1595 certified I don’t know every thing. Never have welded SS to copper this will be my first go around with this configuration. I have not done copper with copper filler in a long time but will give it a shot and see if it will work on SS/copper.
> Thanks everyone.
> CH


cut some coupons and practice and find out.


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## COMachinist (Sep 6, 2021)

Oh yes plan to do this.
CH


woodchucker said:


> cut some coupons and practice and find out.


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## Ken from ontario (Sep 6, 2021)

I work with copper a lot but have never tried to weld copper to stainless steel, if I faced this challenge, I'll try (AL's suggestion, post#2)O/A brazing  with silicon bronze first , then reluctantly will try to see if silver soldering would even work, but that's because I don't have a TIG welder, Ulma Doctor 's way sounds promising.


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## GunsOfNavarone (Sep 6, 2021)

I've done it with silicon Bronze. 100% Argon as this is technically brazing, penetration really isn't the goal.
I love silicon brozne..it's like super glue for all kinds of metal....and purdy!


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## G-ManBart (Sep 7, 2021)

COMachinist said:


> Yeah I know, that is what I have. But you can also use helium, 80/20 helium/Argon,* CO2/argon mix*, Nitrogen for deep penetration. There may be more. Even thought I’m 1595 certified I don’t know every thing. Never have welded SS to copper this will be my first go around with this configuration. I have not done copper with copper filler in a long time but will give it a shot and see if it will work on SS/copper.
> Thanks everyone.
> CH


I'm not a professional, but I haven't seen or heard of a C02/argon mix being used successfully for TIG welding.  Straight argon, straight helium, argon/helium blends, argon/hydrogen blends, argon/nitrogen and even argon/helium/nitrogen blends I've heard of, but some of those are quite specialized.

I only mention this because so many people post on welding forums asking "Hey, I have a MIG and 75/25 gas, can I use it for TIG"....not if you want the tungsten to last more than a few seconds.


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## pontiac428 (Sep 7, 2021)

Silicon bronze on stainless will always be best with TIG running pure argon.  I don't think I've ever seen an engineered joint from copper to stainless that wasn't silicon bronze "welded"/brazed.  Difference in melt temp is really high with those metals.


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## rwm (Sep 7, 2021)

I had no idea you could do this?! You are talking about welding these together without any filler?!
Robert


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## Ulma Doctor (Sep 8, 2021)

copper can't be directly welded to stainless steel as the metals are dissimilar 
bronze based brazing is the only practical method of joining these materials for the job at hand that i'm aware of


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