TIG Brazing

mofosheee

mofosheee

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Hello HM forum

Brazing is new to me. I've been practicing using TIG brazing on 1/16" steel. Although the appearance is fine, my best understanding is that brazing works on the principle of capillary action, does not involve the fusion of metals and that pretty bead doesn't make for a strong joint.
My question is how to enhance the strength of the joint? Is it possible to achieve capillary action using TIG?

Scuff up the metal surfaces to be joined? Use flux? or the better question is do I need flux with TIG?

Thanks to all!
 
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Fillet brazing, where a healthy bead of filler metal is laid on the joint, provides reinforcement. You can also fabricate a reinforcement piece that lies on the joint, which is then joined together by brazing.
 
Nesse1 said:
Fillet brazing, where a healthy bead of filler metal is laid on the joint, provides reinforcement. You can also fabricate a reinforcement piece that lies on the joint, which is then joined together by brazing.
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It appears that I have unwittingly been fillet brazing. Thanks for the response
 
There are a couple of different TIG bronze rods, I think I have the aluminum bronze. You generally don't get much capillary action with TIG unless the join area is relatively narrow, as TIG heats in a concentrated area. If you overheat it just a bit you can get a bit of fusion welding to occur, which might strengthen the joint.

I also recently got some Stay-Silv 5 Silver Bronze which is used in HVAC work and tends to flow better (using a torch) but have not tried it with TIG yet. It is expensive, however.
 
machPete99 said:
There are a couple of different TIG bronze rods, I think I have the aluminum bronze. You generally don't get much capillary action with TIG unless the join area is relatively narrow, as TIG heats in a concentrated area. If you overheat it just a bit you can get a bit of fusion welding to occur, which might strengthen the joint.

I also recently got some Stay-Silv 5 Silver Bronze which is used in HVAC work and tends to flow better (using a torch) but have not tried it with TIG yet. It is expensive, however.
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That's what I suspected about capillary action. I've been using a 0.045 silicon bronze rod with 1/16 tungsten.
My previous brazing attempts using a MAP torch were not impressive.
 
I have oxy-acetylene brazed a lot, and am accustomed to the capillary action, (no fusion welding). Usually preheat the part, (read cast-iron), to about 700 deg. F. Tried silicon-bronze with TIG. Not good results. Apparently, need to use the torch as a heat source, like a carbon-arc torch, with flux? Need to dig out my Welding Encyclopedia and see what it says, if anything, seeing as how it is from the ‘70s.
 
I don't know if this qualifies as TIG brazing, but a friend did this on my motorcycle clutch hub (using silicon bronze rod) after I rebuilt it. All I know is that I was impressed...

P1020585 by nessism, on Flickr
 
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Janderso said:
Tried This Old Tony's method of Silicon Bronze brazing. It actually went pretty well.
Tony makes it look easy.
Definitely adds another tool to the arsenal.

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As he said at the 16:30 mark.......... that a TIG braze joint is different from a gas brazed joint in that the gas brazed joint "wets out" better
gonna have to practice with gas. Thanks for the YouTube vid!
 
I have MIG brazed for over 20 years. Brass just acts differently than steel, it's weird.
I have never had it suck in a joint, can burn away the steel if too hot, It never gets the
"fluidity"(?) that happens with oxyfuel brazing.
I tried TIG brazing once and couldn't get close to making it work.
 
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