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  • File : 1294205018.jpg-(9 KB, 286x400, 3hnds..jpg)
    9 KB Anonymous 01/05/11(Wed)00:23 No.13404195  
    Previous sword thread is on autosage. (Or at least I hope it's on autosage.) Continuing here:

    If you had the money, expertise, and technology to make a sword out of any type of steel you wanted, what type of steel would you use? A list of the elements in the alloy would be helpful, as well as why it would be better than traditional steel.
    >> Anonymous 01/05/11(Wed)00:32 No.13404304
    Can anyone name an alloy that's just as good in a sword as steel used in the Middle Ages (hardness, impact strength, ability to hold an edge, etc.) but lighter in weight?
    >> Anonymous 01/05/11(Wed)00:44 No.13404460
    armchair metalurgist here. I'm not certified/formally educated in this, but I have done quite a bit of research on it on my own.

    building a sword out of "alloys" generally doesn't produce a better sword. steel really is the best suited to the job. it has the right balance of flexibility and hardness. other metals can compare, some can beat it in one catagory or another, but not without losing out in another catagory and losing that desired balance.

    many of the terms we hear associated with sword steel percieved as high quality, like "folded," "damascus," "laminated," "high-carbon," etc... really all talk about the same thing: carbon content and distribution in the steel, carbon being what makes Iron into steel.

    simply put, higher carbon content in steel makes a harder, more rigid steel, but also less flexible, and thus somewhat brittle. conversely, lower carbon content makes a softer, flexible and malliable steel that doesn't hold an edge very well or bends after a bashing.
    >> Anonymous 01/05/11(Wed)00:51 No.13404539
    What's your opinion, then, on them newfangled steels like the 9260 spring steel or the T-10 tool steel?
    >> Anonymous 01/05/11(Wed)00:52 No.13404556

    What, its a standard element.
    >> Anonymous 01/05/11(Wed)00:58 No.13404634
    most "quality" sword steels are "composite" steels. meaning, they take advantage of the strengths of both high- and low-carbon steels to balance its strength. in medieval times, it was difficult to measure carbon content accurately (difficult, not immpossible, but difficult.)

    all of those terms I listed are just composite steels by different methods and names, but the end result is the same. layers of softer steel (usually in the core) give flexibility, while harder steel (usually near the edge) make harder, sharper edges. "folding" also has a homoginizing effect on carbon content. by drawing the metal out, folding over, and repeating the process, it creates overlapping microlayers that helps eliminate "flaws and impurities," or places where carbon content is too great or too little.
    >> Anonymous 01/05/11(Wed)01:06 No.13404758
    I'm not fully familiar with the properties of the steels you mention, but "tool steel" generally denotes a VERY hard, rigid steel. when drawn out into a long, thin blade, rather than a stubby, beefy hand-tool, shattering is common. this is also common with titanium, another very hard metal that is commonly used for tools.

    "spring steel" is often intended to retain a specific shape while maintaining flexibility. the act of reforging and reshaping such a steel into a blade would change its properties.

    anyway, I do know that a fairly common 1080 stock carbon steel is very good for simple blade design. it holds a good shape, it's tough, it takes and gives abuse well, it doesn't warp or shatter easily, and in appropriately tailored weapons, should meet most of your needs.

    next post, more term definitions, and details on "tempering."
    >> Anonymous 01/05/11(Wed)01:12 No.13404816
    Heat treat is more important than alloy, but I'd go with MIL-B-11595.

    It's dense, tough, resistant to set, and hard.

    it's difficult to work with, and would be hard to sharpen, but it's got very good properties otherwise.
    >> Anonymous 01/05/11(Wed)01:19 No.13404881

    This is what T-10 tool steel is like.
    >> Anonymous 01/05/11(Wed)01:25 No.13404953
    "folded" as I mentioned, creates microlayers that equalize carbon content and creates a fairly simple composite steel. now, when you hear about a sword with "thousands of folds" understand that the term "fold" is misused. they mean "layer." 1000 folds would be inhumanly labor-intensive, and self-defeating. the steel is homoginized beyond deffinitive layers after 20 or more, and the longer you mess with it, the more likely mistakes will be made, such as in temprature control. remember that doubling something over ad stretching it 10 times results in 1024 tiny individual layers.

    "damascus" is another composite steel, although it's cooked like a stew rather than pounded out on an anvil. its created in an earthen crucible, it's believed to be based on Indian Wootz Iron. the russians recreated an imperfect copy of the process and created Bulat Steel. the patterning is made by the differences in carbon content and other elements mixed in with the iron in layers. an acid etch on normal steel makes a consumer counterfeit.

    "Katana steel" is both folded and laminated. lamination creates a core of soft steel sheathed in a skin of hard steel, with a very hard pearlite steel along the edge. the pearlite is what makes the "Hamon line." the process is very involved, and varied greatly across its history, and my knowledge gets cloudy and inacurate after this, so rather than misinform, I'll advise you to research it as I did to learn more. Katana, however, aren't really any better than western swords in form or function.

    next up, "tempering."
    >> Anonymous 01/05/11(Wed)01:35 No.13405043
    People in the swordmaking community are jizzing themselves over something called "L6 bainite"... and I have no clue what the fuck it is.
    >> Anonymous 01/05/11(Wed)01:36 No.13405059
    >>Katana, however, aren't really any better than western swords in form or function.
    Worse yet, they only existed because weapon control laws in Japan banned the samurai caste from using effective weapons.
    Tokugawa was a dick, and so they ended up with large numbers of 'samurai' who were not allowed to wield actual battlefield weapons and all got to carry around a poorly-made katana as a symbol of their status.
    And that children, is why the Japanese were fixated on those damned swords for so long.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)01:39 No.13405083

    What contaminants or actual intentionally introduced alloying elements would be ideal for swords? I'd like a metallurgist on what would be feasible with Medieval technology.

    It is posited that several "legendary" or "magic" swords had such "contaminants" producing alloy steel beyond the means of contemporary steel not made from the same ore.
    >> Anonymous 01/05/11(Wed)01:39 No.13405084
    How much would it help to cast your ingots/blanks/whatever you're making the sword from in a zero-G environment, assuming that you're still in the creating-the-alloy stage?
    >> Anonymous 01/05/11(Wed)01:46 No.13405127

    Probably not much at all?

    You have to heat treat the thing after you forge it anyway. You're making the crystal structure of the metal your bitch if you're doing it right anyway.
    >> Anonymous 01/05/11(Wed)01:48 No.13405145

    Wouldn't it be cool to forge a sword under crazy magnetic forces though?

    I wonder if you could set up magnetic fields to improve crystal strength and support structure.

    If only I had infinite time and money.
    >> Anonymous 01/05/11(Wed)01:48 No.13405148
    Hmm. What do you all make of the "mercurial sword" idea?

    There is a reservoir of mercury within the sword that free-flows along its length. When you swing it the mercury flows to the end, increasing the weight at the end for better chopping (sorta like a falcata). When you're not swinging, it flows back so you still have a balanced weapon.
    >> Anonymous 01/05/11(Wed)01:49 No.13405168
    >If only I had infinite time and money.

    Platinum-Rhodium sword, mined, smelted, and forged in zero-G. Go around smiting the homeless with it.
    >> Anonymous 01/05/11(Wed)01:50 No.13405172
    I'd guess that the tricky bit would be creating a sealed reservoir of mercury within the sword without compromising the strength of the sword when you forge it with a cylindrical void running through the center of the blade.
    >> Anonymous 01/05/11(Wed)01:51 No.13405176
    those tests seem poor at best to determine the sword's full ability. chopping a soft sapling, a rotten log, or a rusty tin barrel isn't impressive. the scratches it takes are even less so. I've demolished a metal barrel like that with a 1080 sword and didn't have a knick on it.

    however, I'll concede that he probably had it sharpened to hell, when chisel-sharp is all you really need. too sharp means the edge will fold, chip, knick, and break easier, challenging the structural integrity of the blade and creating weaknesses.

    "tempering" or "heat treating" aligns and compresses iron molecules. the heating excites the molocules, and quenching it in water rapidly cools it, causing the molocules to compress, creating a tighter and more orderly molecular construct, lending greater strength to the overall shape. temperature control is vital, and consistancy is key. temprature extremes ruin the effect. the fire must be a controlled temprature, level at around 1440 degrees F. the water temprature varies as well, and legends tell of japanese smiths cutting off an apprentices hand for checking the water temprature without the master's consent, but something very cold like ice or snow (ala conan) could result in shattering.

    also, remember that the FORM and FUNCTION of a sword are equally as vital to its success as its MATERIAL properties. smaller blades like knives and daggers can enjoy the benifit of stainless tool-steel or even a titanium alloy without comprimising its stability. larger blades can benifit from things like fullers, a diamond profile, tapering, and other techniques to lend it strength and durability while minimizing weight and altering balance and center of percussion to build further resistance to breakage.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)01:51 No.13405183
    If you grew then very slowly in a zero-g environment, you could get larger than normal grain size (metals are composed of very tiny crystalline grains, strength is related to grain size, but both extremely tiny and very large grains produce materials that are stronger than middleish sized ones). I don't know if that would necessarily helphelp.
    If you wanted amazing material properties in metals: either make monocrystalline metals (like a turbine blade in a modern jet engine), or make amorphous (glass) metals.
    >> Anonymous 01/05/11(Wed)01:51 No.13405185

    I feel like having a liquid pocket of material inside the main channel of a sword would hugely decrease its structural integrity, but honestly I have no idea.

    Cool idea, though.
    >> Anonymous 01/05/11(Wed)01:56 No.13405230
    Use platiniridium instead. Maybe a rhodium coating for corrosion resistance.
    >> Anonymous 01/05/11(Wed)01:57 No.13405234

    In something like a medieval longsword yes, but what if it were in something like a sabre, with a thick round back providing support?
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)02:00 No.13405267
    I'm imagining it being very awkward to swing an object around that has liquid sloshing back and forth in it.
    And you aren't going to get any more angular momentum out of your swing than you put into it. So shifting a lot of weight forward at the last moment would slow the swing down so that the same total angular momentum in the sword was present.
    You can't create momentum or energy out of nothing.
    >> Anonymous 01/05/11(Wed)02:01 No.13405270
    A sword? I'd rather take a mace or morningstar. I just like crash-and-bash more than slice-and-dice, you don't get that same visceral thrill with swords.
    >> Anonymous 01/05/11(Wed)02:01 No.13405274
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    It would, and it would also wreck the balance. Having liquid metal sloshing around inside a blade isn't very good for that kind of thing in something that needs to be as carefully balanced as a sword. It's also really a silly idea when you could probably replicate the intended effect by putting a slug of something like depleted uranium towards the tip. Or you could just use something like a grossemesser that was actually intended for that kind of high momentum chopping action without any needlessly overcomplicated design features.

    And if I could, I'd just make a grossemesser out of highest-grade steel. Because goddamn do huge German swordknives ever look sexy.
    >> Anonymous 01/05/11(Wed)02:02 No.13405281

    By sheer fucking conservation of angular momentum, I don't think there's any real advantage over a heavier but balanced sword.

    And there really isn't any advantage in that over a lighter well balanced sword of the same length.
    >> Anonymous 01/05/11(Wed)02:03 No.13405294
    I was thinking more in terms of homogenization of the alloy when gravity isn't acting to separate the components by density, actually, but that also sounds interesting.
    >> Anonymous 01/05/11(Wed)02:05 No.13405303
    One thing to remember, the exact steel quality used is only a minor part in how good a sword is. A good smith with so-so material will produce a much better blade than a so-so smith with good steel.

    >>13404953 creates microlayers that equalize carbon content

    Rather, the "kneading" as you fold the metal over and over, combined with the long time at high temperature, is what allows the composition to even out.

    >>it's believed to be based on Indian Wootz Iron. the russians recreated an imperfect copy of the process and created Bulat Steel
    Patterned crucible steels (wootz being an utter bastard of a term) have been produced from India, through central Asia, to Persia for a long, long time. The Russian bulat isn't an imperfect copy, it's merely their own variant.

    >>an acid etch on normal steel makes a consumer counterfeit.
    Acid etching has been used to bring out the pattern on wootz-like steels for centuries, making it easier to see.

    Read: http://www.mediafire.com/?j1wyomznimm

    >>lamination creates a core of soft steel sheathed in a skin of hard steel
    Or you can take a hard core and add a soft slab on either side, letting the hard bit poke out at the edges. Or the hard bit could be U-shaped around the core. Or...

    >>with a very hard pearlite steel along the edge
    Pearlite is soft, unhardened steel. Hardened steel is martensite (or very, very rarely bainite).

    >>the pearlite is what makes the "Hamon line
    This has nothing to do with the lamination, being instead a result of the differential heat treatment.

    To polish your metallurgy knowledge, read http://www.mediafire.com/?idihdcwz2td and http://www.shibuiswords.com/tatsuoinoue.htm
    >> Anonymous 01/05/11(Wed)02:08 No.13405319
    >>13405059 And that children, is why the Japanese were fixated on those damned swords for so long.

    Interestingly enough, they weren't really THAT fixated on the superiority of katanas until the early 20th century, when the Imperials started to heavily push Japanese nationalism. Before that, western-style sabers were in vogue for the better part of half a century or so.
    >> Anonymous 01/05/11(Wed)02:09 No.13405328
    >>13405059 Worse yet, they only existed because weapon control laws in Japan banned the samurai caste from using effective weapons.

    The katana emerged as a battlefield sidearm for the common grunt, and eventually started being carried by higher ranking soldiers as well, probably due to it being easy to carry and quick to deploy. This also made it a very suitable for daily carry in times of peace, such as the Tokugawa era. Why the fuck would samurai bring full battlefield regalia every time they went out for a drink?

    Adding rarely occurring alloying elements to steel will change what the ideal heat treatment is. And that heat treatment will almost always be far, far more important than the exact steel alloy used. So even if you add something which could be beneficial, if it makes the smiths usual heat treatment not work as well, the end result will be a much poorer sword. What you want instead is ore lacking contaminants which will be bad for the steel, Swedish ore for example tends to be naturally low on sulphur, thus the fabled Swedish steel.

    At the end of your swing, when its time to recover, the mercury would be "out there" when you really need the balance back home.

    In almost all cases, strength increases with grain size. You're looking at monocrystalline materials if you want to gain any benefit whatsoever from a large grain size, and IIRC that's mostly for things where fatigue will be a major factor (turbine engine blades and such). For a sword you want your grain size just above whereHall-Petch gives up (as pushing it into the nanocrystaline range generally embrittle the material).

    Making the steel homogenous is easy enough even in normal gravity.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)02:19 No.13405369
    >>For a sword you want your grain size just above where Hall-Petch gives up
    I was imagining monocrystalline swords and nanocrystalline swords (all that inverse Hall-Petch stuff).
    If nanocrystalline is too brittle, then monocrystalline it is. Growing them from liquid pools of metal will be a bitch, but it is possible (and oh so expensive). I guess you would have to draw columns of metal out of a melt the same way we draw columns of Si out of a melt to make the columns that Si wafers are cut off of. The columns could then be ground into the shape of the desired sword.
    I don't suppose you could ever repair such a sword though.
    Impractical and impossibly expensive you say? Sounds like just the thing for a player character to buy!
    >> Anonymous 01/05/11(Wed)02:21 No.13405378
    googling this...
    some info.

    L6 appears to have a low-alloy content, meaning its mostly iron and carbon, maybe some manganese. other tool steels can contain chromium, nickel, molybdenum, tungsten, titanium, and vanadium. the L6 looks more impressive than the T10 mentioned earlier, but I would prefer to handle an example of each before passing a verdict or anything.
    more easily done if the weapon is single-edged and the resevior is on the back side. however, I don't think the minor increase to efficacy would merit the sacrifice in control. looks cool on a character sheet, though. ever had one of those baseball bats that did that as a kid? really didn't increase velocity of your swing much, just came close to tearing your shoulders up if the arc of your swing wasn't right.

    as for OP's question, Iridium, depleted uranium (meaning less or non-radioactive), and other alloys mentioned above are examples. but if you look at the tool steel wiki I linked, you'll see the extremely low ratios. some as low as 0.3%. most of a sword is steel, and the best swords, chemistry and metalurgy aside, are still steel.
    >> Anonymous 01/05/11(Wed)02:24 No.13405406
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    Titanium infused carbon steel. Not any stronger, but looks badass.
    >> Anonymous 01/05/11(Wed)02:27 No.13405426
    hey, I said at the top in my first post, I'm not claiming to be an authority. I appreciate the fact-checking though. I know the "differential heat treatment" with the clay they paint on is a part of the proces, but I omitted it, thinking "laminated" was a fair enough catch-all for the process. I suppose more detail would have been better, but I assume these guys are smart enough to not take me as an authority on it. and you're right, I probably just crossed the two names in my faulty memory. I'll check out your link, as I'll advise others here to do as well.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)02:29 No.13405447
    What about armor?

    Current trends in armor don't really apply since firearms are dangerous not because the energy the projectile packs (heck, the average knife trust has more energy!) but because the energy is so concentrated, so modern armor has to resist highly concentrated energy and spread it.

    Meanwhile armor against cold steel would need to deal with lot more energy spread over a lot bigger area.

    ...then again, I'm given to understand that the speed of the impact also changes things a lot. Kevlar can stop a bullet, but a slow knife can slice through kevlar.
    >> Anonymous 01/05/11(Wed)02:33 No.13405474
    The thing is that the grain size hardening doesn't embrittle the material at all really until we hit nanocrystalline levels, so by going monocrystalline you're giving up a lot of strength and hardness and in return you get something which shouldn't matter unless you intend for the sword to see daily use for a few centuries.

    And with steel you have an extra headache of massive proportions in the manufacturing due to the phase changes that the steel will want to undergo as you cool it. Good luck keeping it from nucleating more than one grain, especially since most steels will contain more than one phase once all is said and done (and no you can't have more than one phase per grain).
    >> Anonymous 01/05/11(Wed)02:36 No.13405498

    Uh, no, brah. Gunshots carry far more kinetic energy than any stab. KE goes up with velocity squared, so even though bullets are tiny, even a mediocre pistol round carries a kilojoule or so just from sheer speed.

    A fucking heroic sword slice would be lucky to get beyond two hundred joules.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)02:36 No.13405500
    Very dense Boron Carbide is THE solution to bulletproof hard armor. We more or less make BC breastplates for U.S. soldiers to wear. They can take multiple shots from a rifle with no cracking or failure. They are heavy and expensive. Silicon Carbide is used on some vehicles.
    See the Ceradyne corporate website for more info. They make the U.S. military's BC and SiC ceramic armor for troops and vehicles.
    >> Dantalaeon !SSUj4kqmDk 01/05/11(Wed)02:40 No.13405540
    I'd make a thin, pattern-welded blade, heavy on the point to balance out the absurdly long grip. One side would be serrated near the hilt for work like filing through metal girders, while the other side would be sharpened to a razor's edge near the tip. The hilt would be a standard crossguard affair, with a thistle-and-panther themed crest in the center, so people would know to get their own weapon and not cramp on Dantalaeon's. Oh, and there'd be some badass Pictish glyphs on the blade along the blood channel, saying "Mortis Potesta Est" or some badass bullshit like that.

    Oh, and the ribbed grip would taper down into an iron spike, so that I could bludgeon infants more effectively.
    >> Anonymous 01/05/11(Wed)02:41 No.13405545
    >>13405447 Kevlar can stop a bullet, but a slow knife can slice through kevlar.

    As far as I've understood it, kevlar works much the same as old cloth armour (which was quite popular). You basically have a number of layers of fabric, and anything trying to pierce through which isn't sharp enough to cut the fibres (bullets, bodkin arrowheads, etc) will have to tear off the fibres to get through. Due to the multiple layers and the flexibility of the cloth, it has to tear a lot of fibres in one go, which may end up being too much for the projectile. Kevlar simply has a lot stringer fibres than, say, linen.

    Weapons with a sharp edge on the other hand can cut the fibres, making it a lot easier to get through (though the armour wills till be better than nothing of course).

    All said and done though, if you want to stop a blade, then plate armour is your friend. Perhaps with a kevlar pourpoint underneath, and titanium alloy plates where the articulation allows (you can get stronger plates per total weight, but they'll have to be quite thick), but still.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)02:41 No.13405549
    Of course you wouldn't grow monocrystalline steel. You would use some pure elemental metal in order to avoid the problem of concentration changes in the melt as some element in it preferentially crystallizes.

    >>by going monocrystalline you're giving up a lot of strength and hardness
    What? I thought that the exact opposite was true? Monocrystalline metals are far stronger than their polycrystalline counterparts. I could have sworn I heard that in some MatSci class. I'm not sure about hardness.
    >> Anonymous 01/05/11(Wed)02:53 No.13405671
         File1294213982.png-(706 B, 118x47, ph.png)
    706 B
    Yield stress, which I would consider equivalent enough to strength here, goes up as the grain size decreases, as per the Hall-Pecht relation (pic). This is because the grain boundaries obstruct the free movement of dislocations in them material.

    Sigma-y is the effective yield stress, sigma-0 the "base" yield stress, k-y a material constant, and d the average grain size.

    This relationship holds true until the grains get so small that the material is essentially more grain boundary than grain, at which point there's a pretty sharp change in material properties (many metals turn quite brittle for example) and we move into the realm of nanocrystalline materials.

    Now, since grain boundary hardening (as long as Hall-Pecht holds) is one of very few ways to strengthen a material without embrittling it, a small grain size is generally very desirable.

    Now, if we look at fatigue over a long time, letting the dislocations run around however they damn well please will decrease the risk of them tangling up in a big bunch and initiating a fracture, which is good if you're going to have a lot of vibration or so. Should a sword break on the other hand the fracture will almost be guaranteed to have been started by something else, with a large and sudden shock being involved, so there's no need to not lock down the dislocations.

    Well, assuming I haven't forgotten all too much of my metallography that is...
    >> Anonymous 01/05/11(Wed)02:55 No.13405692
    >>13405671 is one of very few ways to strengthen a material without embrittling it

    In the short run, I should perhaps add. You know, looking at a normal stress-strain graph or so. For long term fatigue it can obviously make things a bit more brittle, as per the parts which followed.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)02:57 No.13405709

    Um... no.

    Conservation of momentum means, that the same momentum is applied to your shoulder (through the butt of the rifle) than what the bullet gained... so your shoulder receives the same energy that the bullet packs and somehow you're not all that worse off. (Though a nugget can leave bruises).

    In fact no hand-held firearm packs enough punch to push a man any distance. (No, I'm not talking about the bullet going through and only depositing part of its energy).

    ...so your assurance, that firearms pack a "lot more" energy holds no water.

    In fact since swords are so fucking heavy (600-800 grams) compared to bullets (3-5 gram modern bullet), even at small "speeds" they still pack quite a punch as far as energy goes. Moreover unlike a bullet, a swung sword also likely has angular momentum, so not all of its energy is stored as pure linear momentum.
    >> Anonymous 01/05/11(Wed)03:01 No.13405739
    Momentum and energy are NOT the same thing.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)03:04 No.13405768
    I thought that the Hall-Petch equation broke down outside of the 'normal' range of crystalline grain sizes.
    A single crystal grain that is the size of a sword can't be modeled by the Hall-Petch relationship.
    When a monocrystalline Si column is drawn out of a melt, the very top of this multi-ton column is composed of a very tiny section of monocrystalline Si. One of my matsci professors showed us a video of that and claimed that the little bit of silicon holding up that retardedly huge column was possible because it is a single crystal and has far higher yield strength than regular polycrystalline silicon.
    So I've been thinking (perhaps wrongly) that monocrystalline=way the fuck stronger than polycrystalline.
    >> Anonymous 01/05/11(Wed)03:10 No.13405840
    hate to burst your bubble but steel is considered an alloy made from refining iron and combining (usually) with carbon or other metals

    Steel tends to be best through if you use tungesten in the refining process it makes a stronger blade, but often has to be thicker to get an overall effect

    Ideally a carbon steel blade with a titanium infusion would be superior, along with a soft metal working folded into the sword (such as Vanadium) would give the weapon an increased flexibility without the sacrifice of ridgid cutting power

    Only problem is besides the edge it would require constant maintence
    >> Anonymous 01/05/11(Wed)03:11 No.13405849
    Looking at the mechanics behind everything, I'd suspect that while H-P wouldn't accurately predict the strength of a very large grained material, the strength of a monocrystalline material would simply be Sigma-y, or close enough. We're simply removing one hardening mechanism altogether here.

    >>the very top of this multi-ton column
    Just how big a column where they making? A ton of Si is almost half a cubic metre...
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)03:17 No.13405922
    There was a person in a bunny suit standing near the finished column in the vid. The column was far wider and taller than that person.
    See this vid at 2:50.
    This isn't the same vid we saw in class, but it is a similar scenario. 440lb column supported by 3mm wide section of monocrystalline Si.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)03:19 No.13405944
    So are you telling me, that the bullet has more energy than the rifle recoiling? If yes, then you're breaking the conservation of energy.

    When you pull the trigger, the whole rifle is a closed system. The gunpowder deflagrates and turns chemical energy into heat and pressure of a gas. The barrel transforms this into kinetic energy. At the end the sum total energy of the system has to be what it was before: zero.

    You do this by taking into account the fact the the recoiling rifle and the bullet are traveling in opposite directions. (...and if you did the same for each particle of the expanding air, you get the same result).

    1600 joules (~5.56 or 5.45) are not *all* that much. If expressed as a 0.5 kg object's kinetic energy than it moves at 56 m/s, so a basketball travelling at 200 km/h - getting hit by that would hurt, but you'd only get bruises... or if it was a person (70 kg), then it'd be 4.7 m/s or 17 km/h... so a running man crashing into you has the same damn energy as a bullet.

    ...so stop assuming: more energy = death, death, death!
    It ain't true. How that energy is transfered, how localized its effects are matter a whole lot... which is what bullets are all about. They deposit all that energy through a minute volume of space, seriously fucking up what's there.
    >> Anonymous 01/05/11(Wed)03:21 No.13405969

    Are you fucking retarded?

    As the above guy said, momentum and kinetic energy aren't the same thing. Swords and bows and shit have more momentum behind them than bullets. But much less kinetic energy.

    Let's look at a bow, for instance.


    Looks like a 110 pound medieval bow throws a fairly heavy arrow weighing about 60 grams at about 50ish meters per second, and that was enough to pierce medieval armor at close range. That works out to about 100 joules.

    9x19 parabellum clocks in at about 500-700 joules.
    5.56x45 at about 1700-1800 joules.

    Say you swing a sword. If you want to swing it hard enough to equal the energy of the humble 5.56mm round, you would have to get it going pretty fast.

    Using the energy relationship between kinetic energy and gravitational potential energy, KE = U = mgh, you would have to swing a 2kg sword fast enough that if you let go of it so that it would fly into the air, it would reach an altitude of over 86 meters or 282 feet straight up.

    That seems... unreasonable.
    >> Anonymous 01/05/11(Wed)03:24 No.13406011
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    Don't mind me, just posting my favorite sword photo.

    Just looking at that thing makes the mind boggle...
    >> Anonymous 01/05/11(Wed)03:26 No.13406035

    Nigga you best be trollin'.

    Conservation of energy has nothing to do with that situation. That's fully a conservation of momentum case. The rifle recieves as much momentum as the bullet did, which really isn't that much. The rifle recieves far less energy than the bullet does, because kinetic energy is KE=1/2mv^2 while momentum is p=mv. They have different equations, different units, and describe different things. You are clearly herping so much derp you can't see straight, let alone understand high school fucking physics.
    >> Anonymous 01/05/11(Wed)03:29 No.13406071
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    That is a fine looking blade. Looks really balanced with the pommel, too.

    Pic unrelated, it's the SORD. The worst possible sword.

    >meigil Kilburn
    >> Anonymous 01/05/11(Wed)03:30 No.13406073
    Are those swords suitable for combat, though? There are plenty of oversized swords that are only meant for decoration.
    >> Anonymous 01/05/11(Wed)03:33 No.13406104
    You're confusing momentum with kinetic energy.

    >>The gunpowder deflagrates and turns chemical energy into heat and pressure of a gas. The barrel transforms this into kinetic energy. At the end the sum total energy of the system has to be what it was before: zero.

    No, conservation of energy means that:

    Energy released as the gunpowder burns = kinetic energy of bullet + kinetic energy of gun + energy lost as heat.

    >>You do this by taking into account the fact the the recoiling rifle and the bullet are traveling in opposite directions.

    kinetic energy is a scalar quantity. It doesn't give a rats arse about direction. Momentum is the vector quantity.

    To give you a quck high school physics lesson, we call the velocity v, mass m, momentum p, and kientic energy E.

    E = v*v*m/2
    p = m*v

    If we have a solid "gun" with a mass of 1kg having in empty space, firing a 10g bullet at 100m/s, then conservation of momentum means the momentum of the gun and bullet must cancel out. Now with momentum being a vector quantity, ie directional, we simply need the same amount of momentum in each direction for it to cancel out, and remain zero. The bullet has a momentum of 0.01kg*100m/s = 1kgm/s, so the velocity of the gun post-firing will be 1kgm/s / 1kg / 1m/s.

    Now to calculate the energies of the two, the kinetic energy of the bullet ends up at 100*100*0.01/2 = 50 joule. While the kinetic energy of the gun ends up at 1*1*1/2 = 0.5 joule. So the kinetic energy of the bullet ended up being 100 times larger than that of the gun. Conservation of energy here simply tells us that the amount of energy given off by the gunpowder must be equal to 50.5 joule + whatever losses we had to heat, etc.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)03:35 No.13406120
         File1294216518.jpg-(459 KB, 1600x1369, strong_man_with_gun8660web.jpg)
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    Gun nut here.
    I've read that even puny bullets have fucktons more KE than physical blows from melee weapons. I never bothered to do calculations to see if that is true. It seems true, what with KE=mv^2. Bullets are supersonic, so really high v. Now square that high v. Really, really high KE.
    Pic related. Pro-gay firearm ownership propaganda poster from Oleg Volk for the Pink Pistols political action committee.
    >> Anonymous 01/05/11(Wed)03:36 No.13406135
    >>13405922 440lb column supported by 3mm wide section

    So, uhm, 283 Mpa? Seems more than Si should take, yes, but not by an order of magnitude or so. some other hardening effect at work? Oh well, I'm too tired for this might continue later if there's a thread for it.

    Purely ceremonial.
    >> Tarnished !I5LdJofSDA 01/05/11(Wed)03:38 No.13406163
    Wootz steel. Incredible sword material for its weight.
    >> Anonymous 01/05/11(Wed)03:42 No.13406197

    Yeah, if I could just get an ancient Persian smith to make me a well crafted wootz steel blade, I can't imagine I'd ever need a better sword.

    It's obviously not the platonic ideal absolute perfect sword material, but it's damn well good enough that it shouldn't matter.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)03:44 No.13406213
    According to wikipedia, monocrystalline Si has a UTS of about 7,000 MPa which is fuckhuge. That is something like 35 times stronger than non-monocrystalline iron.
    >> Anonymous 01/05/11(Wed)03:50 No.13406248
    Incredibly hyped perhaps...

    In a historical setting you'd probably get a bit less inclusions than with bloomery steel made from the same ore (nice, but not earth-shattering), but the ore used may have given it a tendency towards the brittle, and non-wootz crucible steel would have been just as low on inclusions.

    In a modern setting (where the bloomery is out) ad the inclusions bit just goes up in smoke, all you're left with is a somewhat inhomogeneous very high carbon steel.

    In short, it's pretty, but otherwise nothing special.
    >> Anonymous 01/05/11(Wed)03:50 No.13406251

    Damascus steel blade, that is.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)03:54 No.13406282

    Bah! I'm really HERPING & DERPING, this is the 3rd version of this post, as I kept realizing I'm writing bullshit.

    Looking at your responses as well as the wikipedia articles, you guys are right. The bullet has a lot more energy than the gun's recoil energy.

    From wikipedia:
    "However the same reasoning applies when the bullet strikes a target. The bullet may have a kinetic energy in the hundreds or even thousands of joules, which in theory is enough to lift a person well off the ground. This energy, however, cannot be efficiently given to the target, because total momentum must be conserved, too. Approximately, only a fraction not larger than the inverse ratio of the masses can be transferred. The rest is spent in the deformation or shattering of the bullet (depending on bullet construction), damage to the target (depending on target construction), and heat dissipation. In other words, because the bullet strike on the target is an inelastic collision, a minority of the bullet energy is used to actually impart momentum to the target."

    ...so yeah, little momentum is transferred to the target.
    The rest of all that energy is spent deforming the bullet and turning your flesh into chunky salsa.

    Now how this compares to the energy imparted by sword wound (...or the fact that imparted energy may have nothing to do with the severity of wounds... help we need a trauma expert!) is another issue.

    So yeah.
    I was wrong.
    I apologize.
    >> Anonymous 01/05/11(Wed)03:55 No.13406287
    Neither figure given there seems accurate. An good boxer can put out about 800-1000 foot pounds in a punch.
    >> Anonymous 01/05/11(Wed)03:56 No.13406299

    Neither figure could possibly be accurate because foot pounds is not a measure of energy at all! It's a measure of force. I find it fully plausible that a boxer could deliver more foot pounds of force than a handgun, or even a big rifle.
    >> Anonymous 01/05/11(Wed)03:58 No.13406318
    I know this is kind of dumb question, but i am on 4chan and this deserve ridicule anyways.

    How feasible/good would a diamond sword be?

    what about a diamond edge sword or a sword that add diamond to reinforce the steel alloy during creation?

    or do I just fail chemistry and physics forever?
    >> Anonymous 01/05/11(Wed)03:59 No.13406324
    That aside, the numbers are what caught my attention. Really? Only 40? That man would have to be suffering from like type 4 osteogenesis imperfecta or some shit to only put out 40.
    >> Anonymous 01/05/11(Wed)04:00 No.13406333
    Foot-pounds is a unit of energy, it's just a godawful one. Go do thermodynamics in Rankine, why not?
    >> Anonymous 01/05/11(Wed)04:02 No.13406345
    Never said it was a good unit. Just went with the units given. Either way that image is shit.
    >> Anonymous 01/05/11(Wed)04:03 No.13406348


    As far as wounding, blade and such are much more energy efficient about it obviously. A scalpel can cult human flesh with hardly any energy behind it at all. Gunshot wounds can be pretty nasty, though, since they kind of tear through instead of cutting. Supersonic rounds can damage some sensitive organs and tissues though hydrostatic shock.

    Energy alone is not a good measure of wounding potential. I suppose beyond a certain point you're guaranteed complete vaporization though.
    >> Anonymous 01/05/11(Wed)04:03 No.13406351
    >>13406282 Now how this compares to the energy imparted by sword wound

    Still kinda herpaderp, as we were looking at how well an attack would go through armour, not what it did afterwards.

    And while energy translates very poorly to wounds (since it can be "spent" on relatively harmless things like friction and elastic deformation), but it translates well into the ability to punch through a thin section of something (such as armour) as long as we're sane enough only to compare relatively similar penetrators.
    >> Tarnished !I5LdJofSDA 01/05/11(Wed)04:03 No.13406355
    A diamond sword would be near useless. Diamond, while being immensely strong, cracks easily. And diamond edged blades are useful for sawing, something you really don't want to be doing with a sword. Ruins the edge, which is why you need diamonds in the first place.
    >> Anonymous 01/05/11(Wed)04:04 No.13406357
    The sword is supposedly that of one Pier Gerlofs Donia, a Frisian folk hero. He was supposedly 7 feet tall, as was his sword, and they say he could bend coins with three fingers of one hand. Whether this particular sword is his, and whether he actually fought with it we'll never know of course, but it the possibility remains.
    >> Anonymous 01/05/11(Wed)04:04 No.13406361

    Oh fuck, you're right. It's foot pounds-force. Goddammit, imperial, having pounds-force and pounds-mass and calling them both pounds.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)04:06 No.13406373
    I thought that the whole 'boxers put out 1,000+ lb-ft per punch' thing was determined by the very wrong method of using their full body weight as the mass behind the punch and the maximum velocity of his fist as the velocity. A boxer doesn't have the full mass of his body in his hand even if he is 'throwing his weight' into his punch.
    A 150lb guy throwing a 70mph punch outputs 15,300 ft-lbs of energy if you just multiply his weight by the max speed of his hand. Better than a lot of bullets, but not in anyway a valid way to find out the KE of his punch.
    >> Anonymous 01/05/11(Wed)04:07 No.13406381
    >>13406213 According to wikipedia

    >> Anonymous 01/05/11(Wed)04:13 No.13406416
    Very true, however. We're trying to figure out the enery of a punch not the energy of a thrown fist. A punch (at least a good one) always involves movement of the body. So it would be both foolish and unproductive to attempt to measure it without the body mass behind it.
    >> Anonymous 01/05/11(Wed)04:14 No.13406419
    Hm, absence of grain boundary sliding? Ah, fuck it, sleep.
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)04:14 No.13406425
    I know to take Wikipedia with a grain of salt, but these numbers do make mono-Si seem awesome.
    Mono-other metals would be even better. Monocrystalline wiskers of other metals have been shown to have astounding physical properties. But we can only grow them in very small quantities.
    In a sci-fi setting you could excuse making swords and armor out of monocrystalline metal by blaming it on super future tech, I guess.
    >> Flaser !!kWYEewwmdrm 01/05/11(Wed)04:14 No.13406426
    Guilty as charged. So whatever can stop a bullet can also stop a blade from penetrating. OK. So current ceramic trauma plates would make one hell of an armor against cuts, stabs, slashes.

    Blunt trauma could still go through, since they're rigid and don't bend like tempered steel plate (though plate probably also only ablated a part of the blunt trauma). However it's not like padding wouldn't be worn under it (just as with plate) if you expect to get blows to hit.

    How thick does this thing have to be? How heavy would an actual suit be instead plates over the vitals?
    >> Materials Science Anon !!SzjHf2VwuIN 01/05/11(Wed)04:19 No.13406454
    But what portion of his mass could be modeled as being in his hand if we were going to calculate the KE of his punch as max hand speed squared times mass?
    Maybe the guys who made that poster used some bullshit method we aren't thinking of that is returning a far too low value.
    But the simple "entire body weight of this man times max speed he can move his hand squared" seems like bs to me. He would have to have that much weight in his hand itself for that to be valid.
    >> Anonymous 01/05/11(Wed)04:23 No.13406476
    Certainly. But no formula would be accurate enough as no pairing of humans punch the same. The mechanics of my punch varies greatly from the mechanics of Pacquiao's.
    >> Anonymous 01/05/11(Wed)04:25 No.13406495

    Well another problem is that it doesn't really transfer straight over like that.

    Kevlar and spectra and such stop pistol rounds pretty well, especially per the weight. But they aren't fantastic against stabbing. It's much more resilient than other cloth, but it's still nowhere near as effective at stopping a stab as, say, 2mm steel plate would be.

    Knives and swords and such can cut fiber but bullets can't be made to have sharp edges like blades so they pretty much just power through soft armor. Kevlar alone just isn't good enough at blocking knife thrusts to be completely relied upon in a life or death situation. That's why there is special armor for prisons and such that includes level II body armor with extra steel mesh inside to stop blades and icepicks and shivs and such.

    Ceramic armor would almost certainly stop any medieval weapon, but I don't know how well it would do against repeated punishment. an alumina plate might well shatter. Boron carbide plates are tougher, but still probably not nearly as good at standing up to a guy whaling on it with a mace as it's weight in steel would be.

    Metal armor really is a good choice to protect against the sort of slashing and piercing and bludgeoning instruments that mankind has relied upon for most of it's history.
    >> Anonymous 01/05/11(Wed)04:29 No.13406521

    The bullets have to power through the soft armor, that is. Not the knives.

    Kevlar is pretty protective, though. An ordinary cop vest is probably more protective than thick boiled leather.
    >> Anonymous 01/05/11(Wed)04:57 No.13406710
    This thread is relevant to my interests. Perchance does anyone have a link to the last one?
    >> Anonymous 01/05/11(Wed)05:13 No.13406791

    It's probably gone now. If not, look back through the pages

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