having a try at tig brazing getting soot

[Richiew]

They grey stuff on the weld just brushes off. It doesn't look that much different to when I had a go. I don't think I had the black soot at the periphery. What does it look like cleaned up?

Quick attempt at Tig Brazing.

Thought I'd have a go with some bits of scrap. Brazing wire isn't cheap and my pet peeve is that the small volume sellers cuts the wires down to 300mm, I think to convince people that they are getting more. I'd rather buy fewer, longer rods. Anyway a few pics. It is a nice process. 60amps dc...

www.mig-welding.co.uk

 

[Brad93]

Still looks too hot to me. Are you sure the base metal isn't melting or making a pool.

Are your rods definitely TIG brazing rods, not gas welding rods. The gas welding rods have zinc in them.

 

[M1CDQ]

just a little wire brushing. yes they are tig rods

 

[Richiew]

You could always do what I did and strip some copper wire. If you are still getting the soot from pure-ish copper then the issue might lie elsewhere.

 

[M1CDQ]

just reading your post as we type

 

[M1CDQ]

i am getting there. Not pretty
using sifsilcopper 968. Going to try and find some sif phosphor bronse No8 or equiv to try. I see its not cheap.

 

[Tigman]

yes
is that my cock up

Try a Thoriated , might be crisper !

 

[Richiew]

I bought my rods from static_arc on Ebay. They don't have any markings on them. You could always try that seller. Ebay shows the seller is currently away until 24/03/2022 though.

 

[Kram]

They look like proper rods, if they were zinc gas rods you'd have white mess everywhere. I dont think your rods are a problem.

Soot is on one side is often from a bad torch angle? Ive had it a few times.

sif phosphor bronse No8

Odd that naming. Phosphorus makes brittle joints with ferrous however this under 0.5% so as not to be a problem.. its mostly just a copper/tin bronze and you probably wouldnt notice much difference.

 

[Munkul]

The black soot is because as Paul said, you're overheating the filler in the arc, it's burning up and leaving residues.
You're also heating up and filling the weld pool like you would with normal filler wire - don't do this. You're not trying to make a puddle, you're trying to heat the metal just enough that the brazing wire will melt onto it and flow.
I actually like to run AC on TIG brazing, as the arc is naturally less focused, the tungsten is rounded, and heat input is lessened. DC with a big blunt tungsten is good, too. Tungsten type is matterless as long as it works on DC.

Diluting the braze with parent metal is bad for strength and you're trying to avoid this altogether.

I have silicon bronze filler which should be the same as sif 968. I really like it.

 

[M1CDQ]

not the smoothest. But an improvement changed over to a diffuser and no10 glass lens

 

[premmington]

Far too hot - 35/40amps DC - pure argon. Clean everything up (no really clean it) and just go faster - you are brazing not welding.

I never use AC for TIG brazing - even thou I got a Lincoln V205T pulse AC set.

Big tungsten - low amps - big rod! Fast and cold! Moderate amount of shielding gas!

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Worthy skill to own/master - TIG brazing in DC - I use it allot.... Fast and cold - you can do this in any postition. This is the problem solving process of choice for repair work. Dissimilar metals out of postion - gas tight joins.

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C9 rods - not Zinc rods for gas welding. 2.4mm or 3.2mm rods (never had any success with 1.6mm rods)

 

[M1CDQ]

tungsten is 2.4mm and 2.4mm rod

 

[Brad93]

You're melting the base metal still