Thread: Question for the welding Guru Grahame

Hi DJ
The Only Guru I know carked it last week.You know the guy that the Beatles saw in India.

As it happens I have seen brass sheet tig welded.
It was a brass pyramid type trophy.

The smart way the guy did it was to cut slivers off (the same brass sheet used for the trophy body) and use them as filler wire.

Ergo, exactly the same metallurgy. Welds beautifully.
Mind you, it takes practice.

Cheers
Grahame
the Elder Welder

Thanks Grahame, they are going to supply me with some scraps and also some brass rod of the same type for me to practice on if it was feasible, so will be giving it a go sometime next week.

One more ???, is pure Argon okay or do we need a blended argon?

I reckon you will be ok with Pure welding argon.The zinc % content of your brass may be the issue.
In atmospheric air, say under the oxy flame the molten zinc content of the brass can overheat and turn to vapor thus rendering the welding work fubar.

Give the scrap a go and if problems are found ,then increase the volume of the gas shielding -n ot the flow speed but the surrounding atmosphere of the item to be welded.

If possible and size permits, I would be trying to build a cabinet or box to contain an argon gas filled atmosphere purged of all traces of oxygen as that is what oxidizes the zinc.

Grahame

No worries

I'll let you know how I get on next week.

I just checked an old text book that had a supporting reference and scanned this

Quote

Zinc Loss
Because zinc is a metal of low boiling-point, brasses are somewhat troublesome to weld where it is essential to have a weld metal of the same composition as the base metal, as is desirable in certain locations where corrosion is of importance, and the oxy-acetylene process has proved more adaptable in this case.

By adjustment of the flame to a slightly oxidising condition a layer of zinc oxide is formed on the molten metal which prevents the volatilization of the zinc and allows a sound weld to be made.

Arc welding, with an electrode core of the same composition, is liable to result in porous weld metal, owing to this feature of zinc volatility,
End quote

Its supports what i was saying- the argon will prevent oxidisation as the flame envelope would.

You should be OK !
Grahame

If not, tough titties!

I ran out of Oxy one afternoon and quite successfully Tigged a few brass fittings to Cu.
DC -
100% Argon
2% Thoriated
Silicon Bronze filler
Real close gap to electrode. (Sharp)
Everything needs to be very clean .
10-12 l/min. (indoors)
No pulse when using filler but 5-10 ? hertz when blending (watch out for under cut)
Machine on 185 amps but pedal down bugger all (35-50 ? after pool wetted)

Biggest problem was the gap in the fittings as they are designed to have solder flow into them.

Thanks for that Riley, gives me a starting point