On Wednesday, June 20, 2018 at 3:05:08 PM UTC-4, Terry Coombs wrote:
On 6/20/2018 12:16 PM, Gunner Asch wrote:
On Wed, 20 Jun 2018 06:36:20 -0500, Terry Coombs
wrote:
Had another chat with the glass bead maker that wants me to fabricate
some tooling . She needs some mandrels made that are a piece of tungsten
rod welded/brazed to a stainless steel handle . The join is not subject
to the full heat of molten glass . Am I right in assuming that a TIG
torch set on DCEN will melt and fuse these two metals without filler ?
What filler is recommended ? I have on hand 308 309/309l , and some 312
in various sizes . I also have some ER70S2 on hand and some Invar42
nickel/iron filler . She indicates that these must be pretty straight ,
no wobbles when they are spun or rolled across a flat surface . I'm
thinking a long vee block with a cutout in the middle , maybe a spring
on one end to keep things pushed together . We're getting into uncharted
territory here for me , I'm open to suggestions - that pertain to the
task at hand , please .
Tungsten cannot be "welded". It can be brazed..and it can be "silver
soldered"..but it really cannot be "welded"..
https://www.brazing.com/products/Bra...ingFluxes.aspx
http://www.carbideprocessors.com/pag...n-carbide.html
Im sure others here have done this far more than I have...Im looking
forwards to their responses.
Its an interesting problem!
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Â* This project uses metallic tungsten , not tungsten carbide . If my
TIG welder can get an arc hot enough to ball the tungsten , I'm pretty
sure it can melt it on the positive side of a DC arc .
--
Snag
Yes , I'm old
and crochety .
Get off my lawn !
Bad juju. Tungsten is very difficult to weld, even to itself. It oxidizes rapidly at 950 deg. F and it's prone to cracking. It forms nasty, brittle intermetallics with some brazing metals. In my mixed-metal laser welding references, I find nothing that suggests it can be welded to steel of any kind, and nearly all of the mixed-metal commercial welding today is done with lasers.
It can be silver- or gold-brazed in a protective atmosphere. But the authorities recommend press- or shrink-fitting or mechanical joining (bolts, etc.) if the configuration will allow it.
Good luck.
--
Ed Huntress