Tungsten or tungsten carbide(-cobalt) points?

Cereleste

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The points are universally referred to as tungsten, including by the manufacturers.
In comparison photos, tungsten X10 points are pretty close to half the total length of stainless steel ones and have a pretty similar profile. This gives a density close to 16 g/cm^2, noticeably longer than would be expected for tungsten metal.
Tungsten has a density of about 19 g/cm^2, while pure tungsten carbide is at 15.6 g/cm^3 and "cemented carbide", which is tungsten carbide powder sintered with a cobalt or sometimes nickel binder phase (commonly also called "carbide" or "tungsten") has a density between 13 and 15 g/cm^3. All three are shiny, gray, brittle, and dense. Most tungsten jewelry and tools are made from cemented carbide, which is much easier to process and has better properties for those tasks.

There are a few ways to determine which of the three materials it is, but as I have neither X10s nor any "tungsten" points, I can't carry them out directly. I have no direct stake in knowing the answer either; I'm just curious. If anyone has some tungsten points and spare time, these are some different ways:

1 - easiest: cemented carbide is strongly magnetic due to the cobalt (or nickel) in binder phase, while W and WC do not have any noticeable magnetic properties.
2 - photographically - if someone can take a picture of one next to a ruler, from a long enough distance that there's no obvious distortion, then I can use imageJ to calculate the volume.
3 - if you have a scale accurate to a gram or less, and some string or thin wire (and maybe a bored but inquisitive child), the Archimedes method involves suspending one or several points in a glass of water by a small string so the mass of water displaced is indicated on the scale. One point should displace somewhere between 0.4 and 0.6 grams of water.
4 - if you have a broken point, I'll cover UK postage for you to send it over and I can do 1-3 myself, and send it back if needed.
 


Whitehart

Well-known member
Your post is useful because there are forgeries now filtering the market which are not what they should be.
 


chuffalump

Well-known member
Interesting. In number 3 are you planning on using scales to work out the density of the tips, thus allowing you to determine if they are pure tungsten or not?
 


Stretch

Active member
Interestingly mine are very slightly magnetic and there is no question over their provenance :sneaky: You might not notice if fitted to an arrow but you can move them using a office board magnet. (Can’t pick them up).

This is a slightly used 120grn point. Still has a little hot melt residue but they were weighed prior to use and weighed the same so less than 1gn.


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Have fun!

Stretch
 


bimble

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Fonz Awardee
Ironman
Interestingly mine are very slightly magnetic and there is no question over their provenance :sneaky: You might not notice if fitted to an arrow but you can move them using a office board magnet. (Can’t pick them up).
Likewise, my Easton tungsten points are also slightly magnetic
 


little-else

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most darts are made of tungsten copper
tungsten can be bought soft, which is still sintered W sponge, just an effect of how the metal is extracted from the ore. This can be lathe turned but clogs your bit quite easily.
Most commercial titanium is an alloy, likewise niobium, zirconium etc even though they are not usually specified as such.
Some metal refiners use portable x-ray analysers to test the scrap they buy in. try popping into somewhere like Cooksons/Exchange findings in Hatton Garden (Vittoria St brum ) and ask if they can test it for you. As they handle Ti and Nb jewellery findngs they shouldnt think it so odd.
 


Stretch

Active member
To be honest I don’t really care. The company that makes the points for Easton make some pretty funky (and very dangerous) stuff. So I am guessing they are more capable of working out the materials suitability/cost benefit. But I happy to help the crazy diamonds shine :p

I’ve been shooting them for many years. I have damaged one, I shot it into a rock (don’t ask). It is still straight but has a score up the edge so needs rotated away from the clicker. Still weighs the same despite the damage. It is age to say that they are quite robust.

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Stretch
 


Cereleste

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Compared with steel, the metal, its alloys, and the carbide cermet are all very hard, brittle, and dense. Tungsten carbide as a material is about half the cost of tungsten alloys, but the difficulty of processing the carbide is likely to level out the cost or make the latter more expensive.

While looking for more images to compare, I stumbled accross this video which happens to have a closeup of Easton's packaging which says "93% tungsten". So that settles most of the question. The most common slightly magnetic alloy with 93% tungsten has iron, nickel, and molybdenum and a density of 17.7 though.
Using @Stretch 's image and dividing the point into a cylinder, a frustrum, and parabolic cone, I get 361 mm^3 excluding the breakoff sections giving a density of 17.9 with an error of around +-0.5.

Calculating the volume from the spec from these offbranded ones from a chinese tungsten alloy metal company, I get a density of 18.3 g/cm^3
Shaanxi Xinheng Rare Metal Co on Alibaba mentions a 95%tungsten alloy with 5% Ni+Fe with a density of 18 that's slightly ferromagnetic. But the images/description/numbers in the listing are all over the place.

So that settles my curiosity; they're all probably a few different tungsten alloys containing Ni+Fe and are therefore a bit magnetic but nowhere near as much as tungsten carbide point containing 10% cobalt would be.
 


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