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This is about a fictional material that is meant to be very similar to steel, but very brittle (under regular conditions). This means it breaks under stress instead of being strained signficantly easier than regular medieval-technology steel.

Brittle vs. Ductile

All properties of this material such as

  • density
  • potential sharpness

are supposed to be identical or similar to medieval steel.
(Changes to certain properties are legitimate if required, but should be explicitely noted.)

Could this material be used to create splintering projectiles to increase harm to soft targets compared to traditional materials?

The issue I see is that an arrowhead from a brittle steel could easily splinter before entering a soft target and thus achieve significantly less than a normal steel arrowhead.

Answers should elaborate on how projectile designs would have to be adapted compared to traditional designs to benefit from the brittleness of the material and offer an in-target splintering effect.

Note: projectiles meant are primarily arrows and bolts.

This question is part of a series regarding weapon and armour design using fictional materials with unique properties

  1. Weaponry made from extreme light-weight steel: swords and daggers

It is allowed - though not required - to incorporate materials from previous questions.

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    $\begingroup$ So how is what you want different than a obsidian arrowhead? $\endgroup$
    – John
    Jul 16, 2018 at 15:31
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    $\begingroup$ Cast iron had historically been used for projectiles, but its drawbacks (compared to malleable steel) outweigh the benefits. $\endgroup$
    – Alexander
    Jul 16, 2018 at 17:22
  • $\begingroup$ Consider using this to make armor as well, a second layer outside others. Wgen it gets hit it breaks which absorbs and scatters the energy of impact like a ceramic strike plate in a kevlar vest (possibly throwing debris at attacker in process). I dont have enough info on whetger this provides better protection than conventional steel to justify more than a comment. $\endgroup$
    – Seserous
    Jul 17, 2018 at 3:05

5 Answers 5

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The most effective use I can think of for such a material would be to make barbed heads using the hard brittle metal to form a sharp point, still good for piercing armour. The point would protect long fragile barbs that point back along the shaft and break off in the wound to cause further bleeding and infection.

As a note, the modern equivalent is the frangible round and the biggest problem with them is that they routinely do break up under conditions that they're not supposed to, like when they're fired, or sometimes even when they're loaded.

Side note; this material would be good for assassin's blades since it would be very easy to engineer it to break off and break up in the victim making concealing the weapon after the fact much easier since it's just a hilt rather than a bloodied knife and making the wound much worse.

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  • $\begingroup$ That assassin's blade idea is really nice. All you'd need is to have the hilt connection made from this material and then bend it sideways to make it break off. $\endgroup$
    – ArtificialSoul
    Jul 16, 2018 at 12:03
  • $\begingroup$ The brittle-barbs idea is a very good. A similar design is used in quite a few stone arrowheads from pre-history. $\endgroup$
    – Ynneadwraith
    Jul 16, 2018 at 12:06
  • $\begingroup$ @ArtificialSoul Yeah you could do that, I was thinking something in a pre-weakened multi-section blade made entirely of very brittle material so instead of one piece in the wound there were half an dozen or more. $\endgroup$
    – Ash
    Jul 16, 2018 at 12:06
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    $\begingroup$ It's not worse for the victim when the blade remains in the wound. It acts as a plug so less blood leaks out. $\endgroup$
    – user31389
    Jul 16, 2018 at 14:42
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    $\begingroup$ @user31389 It is when the blade comes apart into several pieces that each do more damage with every breath. $\endgroup$
    – Ash
    Jul 16, 2018 at 14:42
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Consider carbon steel, the real world analogy to what you have invented. High carbon steel is less ductile = more brittle than low carbon steel. It is also harder and so holds a sharp edge longer. Therefore high carbon steel is used for things like razor blades. No-one expects a razor blade to flex or survive an impact. Carbon steel is for cutting. Other stuff can do the grunt work.

So too your arrows. If you can make cutting edges from your brittle steel, great. Alloy them or otherwise affix razor blades of your brittle steel to a less brittle metal or even wood - that will back them up and carry them where you want them to go.

I seem to recall reading about sword making techniques where the smith arranged that the carbon content of the metal that would become the blade was greater than that of the body of the sword, but I cannot find a link.

The thing about arrows which makes your tech less useful is that arrows are not knives. You can sharpen up low carbon steel just as sharp as high carbon. Heck you can sharpen ceramic just as sharp or sharper. The high carbon steel is hard and so it holds its edge as you are chopping vegetables or enemies. If you are a sharp arrowhead, you only need to cut once.

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  • $\begingroup$ "I seem to recall reading about Sword making Techniques" - varying the amounts of carbon in steal, in sword making was often the key to the Samurai Swords success, mixing hard brittle and soft flexible steal together in the right amounts and cooling in the right amounts... $\endgroup$
    – Blade Wraith
    Jul 16, 2018 at 12:26
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    $\begingroup$ Also... Why people always try to "improve" arrows and arrow heads... they seem to forget that they are already incredibly effective and doing what they do already, most things like splintering heads etc have been tried over the years and yet the cost to produce a Fire and Forget weapon often are quite large especially compared to the meager benefits of these changes over the "normal" head, the only time that arrows are not effective when hitting someone in the chest is in Computer Games, in real life you have to go a to a lot of effort to protect yourself from "primitive" arrows $\endgroup$
    – Blade Wraith
    Jul 16, 2018 at 12:29
  • $\begingroup$ @BladeWraith The setting where this supposed to be used is a high fantasy / dark fantasy world and thus includes creatures against an extra bit of damage from arrows such as this might boost your survival chances significantly. $\endgroup$
    – ArtificialSoul
    Jul 16, 2018 at 13:06
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    $\begingroup$ @ArtificialSoul, The issue often comes down to cost, 1 simple arrowhead is almost always cheaper than ornate or complex designed to break ones, thus meaning you could fire several arrows compared to 1 expensive one, the "added" damage done with splintering shots takes time to work so speed of kill is not important in this instance, and 2 primitive arrows would always do more damage than 1 splintering one. , perhaps instead of splintering you should have sharp slender arrows that are designed to fall out of the victim to increase bleeding instead of splintering. similar effect, a lot cheaper $\endgroup$
    – Blade Wraith
    Jul 16, 2018 at 13:34
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    $\begingroup$ High carbon steel is not the real world analogy to what he just created. Pig iron is. Furthermore razor blades are actually made from strain hardened mild steel - train tracks - and they have a fair amount of flex in them. Lastly, you can just outright bend high carbon steel even when it is hardened to 60ish. Angel swords did it. It's less about what the material is and more about it's matrix. $\endgroup$
    – user32463
    Jul 16, 2018 at 16:45
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There is an existing real world precedent that seems to be very similar to what you're talking about and certainly has the desired effect:

Frangible Ammunition

These bullets are made of a very brittle metal designed to shatter on impact.
They are most commonly used in small game hunting for their ability to VERY quickley, efficiently (and I guess painlessly) kill small or medium game.

Frangible varmint bullets are designed to break up on impact (explode is the common, though slightly imprecise, term.) Soft lead cores, sintered metal cores and thin gilding metal jackets make these projectiles incapable of staying in once piece at high impact velocities. The idea is for them to disperse their kinetic energy radially in small targets where deep penetration is not only not needed, but counter productive.

Source (Which provides an excellent "breakdown"(ha!) of the application of frangible ammunition)

I personally can't vouch for the effectiveness of this in an arrow or bolt instead of a bullet, but apparently we're not the first people to consider this idea, as a quick google search reveals that frangible arrows have already been patented!

enter image description here

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  • $\begingroup$ Wow, that's a cool find! That looks suspiciously similar to the idea I described in my answer, only they beat my be 50 years! $\endgroup$
    – Cort Ammon
    Jul 16, 2018 at 22:31
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The key to such a frangible round is the design. Once the material is chosen (as you have), the shape of the round is key. In the case of modern firearms, the shape is more or less decided upon, but in the case of medieval arrowheads, there's more freedom.

I'd say the most important requirement for such a round is that it needs to break up in the target, but not under other high-stress environments like being launched. If you look at the time you have to accelerate an arrow with a bow, it is on the same order of magnitude of the forces decelerating it at the threat. This means your shape has to make these forces asymmetric. They need to make it so that pushing on the front yields different results than pushing on the back.

I would recommend an arrowhead which looks something like a fishing spear:

Multi pronged modern spear

Fishing spears have long had multiple tips. It stabilizes the dynamics of the strike, making it easier to ensure the tips do actually strike the fish. What we need is slightly different, but the same design might work.

Consider if these 3 tips were designed to break off at the base. Put a weak point there to make sure they break at the intended place. Now, if you can hit the target with this, it'll break into three pieces. Now we have to figure out how to get it to the target. The forces will be similar in nature to the forces of the bow. There's a few things we could try:

  • The entire arrow will be more massive than the head. This means accelerating the head using the shaft of the arrow will require less force than decelerating the shaft via the head. If your weapon makers can ensure that the break point of these brittle headed rounds is between those two, then you'll be set!
  • Make the shaft hit like a hammer. If a decent portion of the mass of the arrow was in the from of tethered weights loosely attached to the arrow, you could shatter the head with more ease. When the arrow hits, the weights keep moving forward like a passenger without a setbelt until they hit the tethers and apply an impulse to the arrow. Brittle objects have trouble withstanding impulses, so it could be like hitting a sheet of glass with a hammer. Drawback is the weights. Arrows are more stable if the weight is near the front.
    • If you're feeling exotic, you could have fun with this. There is a legendary Chinese weapon which is a bamboo staff mostly filled with mercury. The idea was that the staff would hide the position of the mercury, making it hard to predict where the staff would go to. The mercury also makes for an incredible hammer effect because mercury likes to pool together. If you made an arrow like this, the mercury would pool together mid flight inside the shaft of the arrow. On impact, it would move forward as one mass until it hits the front of its container, just behind the head. This permits the weight to remain near the front of the arrow, but vastly increases the amount of work required to make each arrow, so it might not be economical.
  • You could make a breakaway holder. I'm thinking of something like a sabot, but which might separate on impact rather than in flight. I'm envisioning a small disk that fits between the tips of the arrow and wraps around them. It holds the tips together during launch, so they don't break under acceleration. However, upon impact, the person's body would push the disk back so that it no longer holds the tips together. After that point, they could shear apart.
  • I recommend not using straight shapes to do this. A slight curve would splay the trauma out, increasing the likelihood of it doing lethal damage. This could be an outward curve, but that might have funny aerodynamics. If you bend the tips inward, they will cross inside the target's body and then splay outwards without sacrificing aerodynamics.

In all cases, the big challenge will be economics. Designing an object to break apart under the precise correct conditions is more difficult than making something which is never intended to break apart. The engineering tolerances are going to be tighter on such rounds. Fortunately for this question, manufacturability is out of scope, so it looks like the answer is "yes, yes, you can."

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Projectiles or blades which leave splinters in the victim are very nasty/effective things, this depends whether you are on the receiving end or not. However, I see some potential issues.

Durability While arrow heads, which break on impact can be quite devastating to the victim, you want to avoid breaking the brittle arrow heads during transport. Medieval roads are, if they exist, not the smooth ride we are accustomed to. Thus, you need to make sure that your splintering arrow heads do not break in-transit. The medieval way to store and transport arrows, was in barrels.

Durability II Another issue would be, not to over-do the brittle-ness. A brittle arrow head, which breaks upon impact on a bone ruins your day if you are hit by such an arrow while unprotected. But what about wearing a gambeson. Textile armor is very cheap, and technologically accessible. Even the poorest combatant can wear layers of clothes. Thus, your arrow heads need a certain degree of strength, so they do not shatter upon impact. If the arrow head splinters at first contact with clothing, your arrow may as well have been shot with no arrow head at all. A hit with a blunt arrow, can be nasty when unprotected, as shown by a medical professional with some pig carcasses; note: this source is in german, but the images are both graphic and informative.

And now some actual input:

Answers should elaborate on how projectile designs would have to be adapted compared to traditional designs to benefit from the brittleness of the material and offer an in-target splintering effect.

In order to benefit from the very brittle material, I would suggest the following:

  • Make Bodkin points. Brittle Bodkins should have a higher chance of penetrating clothing than barbed points. The barbs experience bending forces upon impact, whereas the Bodkin experiences compressive forces. Brittle material are better at handling compression rather than bending forces.
  • After assembling the arrow. Fill a arrow head shaped cuo with liquid wax, immerse the arrow head and let the wax solidify. This way you holster the brittle business-end of the arrow to protect it from damage during transport.

And now for something slightly different:

Create an insanely brittle material, e.g. Prince Rupert's drops

Arrows or other projectiles made from this material explode into a gas of sharp shards causing immense danger to the opponents' eyes. A blinded enemy is nearly as good as a dead enemy.

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