Sciencemadness Discussion Board

Tungsten rod not pure ?

metalresearcher - 24-12-2022 at 11:29

For using as an anode for an electric arc furnace I ordered two W rods of 200mm long x 5mm diameter.
https://www.ebay.com/itm/224180442907
I received them after a week and they indeed appeared like tungsten, felt rather heavy.
Then I checked the density and it appeared to 53g per rod which means 53g/((0.25cm)2*pi*20cm) which means 13.4 g/cm3, well below the real density of W which is 19.3.

Or is it really 'cemented tungsten steel' which means a steel core with W wrapped around it which explains the low density ?

And is this really 99+ % W metal ?

https://www.ebay.com/itm/314087659398

violet sin - 24-12-2022 at 12:09

Get a tig welding rod pure W. 3/16" is almost 5mm but they not cheap. I see ~75$ US for 7pc pack?


Cemented Carbide vs Tungsten Steel
https://www.samaterials.com/content/cemented-carbide-vs-tung...

Generally speaking, tungsten steel is smelted by adding tungsten raw materials into molten steel by steelmaking process, and its tungsten content is generally 15-25%

Chemetix - 24-12-2022 at 12:11

The wording 'Tungsten steel round bar rods' is a giveaway....Tungsten steel as in a steel alloy containing tungsten.

Fulmen - 24-12-2022 at 13:19

The designation isn't correct , but I think it's safe to assume it's 'K10 Cemented Tungsten Carbide':
https://carbide.ultra-met.com/item/iso-grades/iso-grade-clas...

Basically it's a high strength composite composed of 94% tungsten carbide in a 6% cobalt matrix. You need to look for welding electrodes.

You should also familiarize yourself with the available types:
https://www.thefabricator.com/thewelder/article/consumables/...

metalresearcher - 25-12-2022 at 00:40

Quote:
You need to look for welding electrodes.

Something like this from Amazon ?
https://www.amazon.com/s?k=tungsten+electrode&crid=1QIKZ...

violet sin - 25-12-2022 at 01:10

Green for pure tungsten. I'm a fan of orange, 4% thoriated for my collection of radioactive oddities collection. There are different colors for a quick reference to composition. In the TIG environment, some run better AC or DC and react to frequency diff. I'm a newbie to TIG, have the machine but still looking for n argon bottle I can afford.

Here maybe try this
3/16" pure tungsten ~75$ US
https://www.amazon.com/Pure-Welding-Tungsten-Electrodes-Gree...

Fulmen - 25-12-2022 at 01:15

Yup, that's the right stuff.

Mateo_swe - 30-12-2022 at 14:29

The second ebay link in OPs post states its pure tungsten rod 99.99%
But they are only 100mm long and a 5mm diameter is 12.89 GBP or about 14,5 Euros.
Seems they have lots of different thickness, 2 to 15mm diameter.
The TIG tungsten rods i think is pure tungsten also but there is different variants so choose the pure tungsten one.

A 10Liter 100% Argon 200bar bottle in Europe is about 150 Euros on Ebay (one time use bottle).
You could buy a refillable bottle and then the refills are cheap but the refillable bottle is expensive.

Admagistr - 30-12-2022 at 14:35

Quote: Originally posted by Mateo_swe  
The second ebay link in OPs post states its pure tungsten rod 99.99%
But they are only 100mm long and a 5mm diameter is 12.89 GBP or about 14,5 Euros.
Seems they have lots of different thickness, 2 to 15mm diameter.
The TIG tungsten rods i think is pure tungsten also but there is different variants so choose the pure tungsten one.

A 10Liter 100% Argon 200bar bottle in Europe is about 150 Euros on Ebay (one time use bottle).
You could buy a refillable bottle and then the refills are cheap but the refillable bottle is expensive.


It's the one marked in green! That's pure tungsten!

Sulaiman - 31-12-2022 at 04:38

I used tungsten rods like the ones in the second link for spark gap tesla coils,
the erosion was so negligible that I believe they were/are pure tungsten.

Fery - 1-1-2023 at 09:22

Just visit welding shop personally and tell them that you want pure tungsten electrodes. In my country they are 99,8% pure W (green electrodes). I bought also the mentioned orange electrodes which contain 4% ThO2 - the e-shop even contacted me that they found few more orange electrodes, whether I do not want to buy them too (because I bought all they had in their e-shop system), that nobody uses them today for welding due to toxicity so they gave me a discount (wanted to get rid of them). Owning this form of Th is legal in my country.