Cost effective replacement material for carbide steel penetrator 1

[paul1975]

I am currently exploring materials which could be used to form penetrators. We currently work with sintered carbide which is expensive and makes up a significant percentage of the overall cost of end product. We are looking to penetrate steel sheets of varying thickness in the 320-370HB region. The penetrators travel between 600-800m/s. Carbide is obviously very effective and shows no deformation at all leading me to think it may be overkill. I am looking at modern alloys for a possible alternative and would love to hear some opinions on this.

 

[EdStainless]

You could look at a CPM grade like 15V and use a TiN coating on it.
But don't the carbide parts last forever? Why is this a major cost?

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[paul1975]

Thanks for the reply. It is a major cost because they get shot downrange and disappear! I do not need them to last forever, just to get through the plate. if a cheaper material can go through then that will be the better choice...

 

[arunmrao]

A hint, can you consider a cast alloy containing Co and V , as used for piercing mandrels in steel tube making.I had developed this alloy casting in the past.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[paul1975]

Thanks for the response. I will investigate your suggestion.

 

[Maui]

Try CPM Rex 76:

http://www.crucible.com/eselector/prodbyapp/highspeed/cpm76.html

Maui

 

[tbuelna]

Seems like a dense metal like tungsten would work well for a steel piercing tip. A stellite alloy might also be worth looking at.

 

[WKTaylor]

Paul1975

Hmmmm... 600-to-800-m/sec [1970-to-2624-Fps] is a snail's pace for ballistic penetrators: no wonder You have trouble...

Ballistic penetrators perform with greater 'punch' [penetration power] when density, toughness and velocity are combined with: (a) impact factors such as instantaneous angle of attack/motion; (b) onto a target's surface [preferably of relatively low obliquity]; and (c) post penetration fragmentation and/or pyrophoric action.

in-other-words...

A high hardness/strength penetrator-nose/shell [high tool steel?], combine with a high-hardness/density core [Tungsten alloy] and highly stable flight [no wobble] to impact ... combined with a spalling/shattering and/or pyrophoric action on exit of an armored wall.

I tend to think that variations in geometry of the penetrator-nose/shell might prove to have a significant influence on the initial 'stickiness' on the target surface, penetration initiation IE; tendency to draw-penetrator deeper... or deflect/ricochet the penetrator.

I wonder if instantaneous rotational velocity on impact [VS no significant projectile rotation] might also be a factor for penetration initiation???

Regards, Wil Taylor

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[IRstuff]

Why do you need a pre-formed penetrator? That takes up volume that could be better used for other things. Why not use an explosively formed penetrator? Our "friends" in Iraq and Afghanistan use homemade EFPs made from copper plate.

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[Wrenchbender]

OP is trying to optimize cost vs performance since now there is too much of both. One step down WCs would be the (cheaper) traditional low alloy steel penetrators - not quite as good, but maybe good enough and not quite as expensive. I'm not aware of any low cost material or manufacturing innovations that would meet the goals.

If this is an R&D program, another parameter to eventually consider is production volume. For gun fired ammo (either spin or fin stabilized) typical procurement quantities are in the 10^5 – 10^7 range, so the raw material should be easily processed. Another parameter is the threat level. If high (say like a tank or an incoming missile), the better performing alloys of Co, W, Ni, etc. might be considered because you may only get one chance at the target. (U-238, called DU, as used in 20mm and 30mm ammo gives great performance at low cost, but there are some environmental concerns.) Incidentally the area of penetration mechanics and material behavior under high strain rates has been researched for many years, in many calibers by the DOD and the national labs.

 

[tbuelna]

Can you provide more details of the target material thickness, the construction of the projectile, and how it is propelled at the target? Switching from a dense carbide material to a less dense metal can affect ballistic performance due to the change in mass.

 

[paul1975]

Thank you for the replies. The penetrators we use are for small arms (rifles) hence the muzzle velocity being "slow". The muzzle velocity is dictated by the max pressure figure which must be adhered to in order to prevent catastrophic weapon failures. 900 m/s is approximately the upper limit for most common small arms projectiles. The penetrators sit in a copper or brass jacket. when the projectile hits the plate the soft brass or copper disintegrate and the tungsten carbide penetrator continues through the target. The targets are generally hardened steel plates in the 300-500HB region. These plates represent light armor which may be encountered on light armored vehicles or personal body armor plates. Currently the penetrators work very well but they are expensive. Reducing penetrator cost would allow us to be more competitive on pricing.

 

[EdStainless]

A tool steel penetrator is an option, but it would have to be a lot larger than the WC one to keep the weight and momentum up.
What about solid W (not carbide)? I don't know if it would work in small arms.


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[tbuelna]

paul1975-

Thanks for the additional info.

The target material you are using sounds like MIL-A-46100 or the typical AR500 steel plate used for range targets.

The muzzle velocity of ~900 m/s is similar to that of a typical 5.56 caliber AR platform with a longer length barrel. The common M855 cartridge (MIL-C-63989) used by the US military has a steel penetrator tip that is required to penetrate .135" thick mild steel plate at 600 meters. It might be worth taking a look at the development history of the M855 cartridge since it could provide some insight on what metal might work for your application. There should be plenty of public source information on the subject.

 

[IRstuff]

One major issue I see is that changing the material itself could change the impact characteristics of the penetrator, which means that you've potentially lost correlation to all the test results from the past. Any test discrepancy in the future could potentially be blamed on the changing of material. Note that it's not just a matter of weight and hardness, but also stiffness, CG, etc.

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