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Twin Blades of Destruction

Nothing like a good night's sleep forced by involuntary keeling over to make you feel like a new TEUNC.

Boy, that was some ladies' short program in the Winter Olympics last night. Talk about oneuppersonship!
(All you fellow Michelle Kwan fans: are you watching anyway and cheering for Team USA as we are, throwing stuff at your screen, or ignoring the games entirely this time?)

Apropos of the title (I'll bet you thought I was talking about skates) - I granted an interview on computer graphics today to an undergrad from another department, who incidentally claims to have designed a very powerful sword. Now, my skepticism tends to kick in when I hear phrases such as "put every weapon on the market to shame" and "twin arcs of death", long before "cut through concrete like butter", "slice into tanks", and "folded 1000 times" come into play. But seriously, he made me curious about something: other than mere cost (and this includes a forge of sufficient heat), is there any constraint or desired quality that keeps swordsmiths from making blades out of pure titanium? For instance, is there any advantage in tensile strength, malleability, etc. to using a titanium-steel alloy?

In other news: I've hired weninger officially now, for a couple of projects. (Welcome aboard, dude!) Now it remains to fill the ITR position in information visualization and one other position. Any good undergrad programmers at K-State reading this are encouraged to apply!

--
Banazir

Comments

( 9 comments — Leave a comment )
masteralida
Feb. 23rd, 2006 11:57 am (UTC)
You have GOT to get more sleep! /nag
banazir
Feb. 23rd, 2006 11:59 am (UTC)
Dknot go gentle into that gnught
We TEUNCs have a saying! "I'll sleep when I'm deead... mazbe."

But seriously, bed calls. G'night!

--
Banazir
marm
Feb. 23rd, 2006 01:29 pm (UTC)
Watching and cheering Team USA. Why not? I've nothing against the other girls, and it's not like one of them is going to change the fact that MK dominated the sport for a decade and is the most decorated figure skater in US history. If Kimmie Miesner or Sasha Cohen go on to have a similar career, I'd be very happy for her.
cybercerberus
Feb. 23rd, 2006 03:53 pm (UTC)
Seconded, exact sentiment.

And Sasha Cohen just ROCKS anyway.
banazir
Feb. 24th, 2006 01:06 am (UTC)
Oh, yes, I agree
It's actually the parents and friends of my friends who say they aren't watching any more. I've been following Sasha and Kimmie's exploits avidly.

--
Banazir
crypthanatopsis
Feb. 23rd, 2006 03:36 pm (UTC)
Folding swords more than 30 times or so is generally useless, as the blades are typically less than 2^30 molecules thick.

In my understanding, titanium is far too rigid to make swords out of, but I also never really understood why swords had to be bendy anyway.

Full disclosure:
IANAS (I am not a swordsmith)
IANAM (I am not a metallurgist)
wudu_wasa
Feb. 23rd, 2006 08:37 pm (UTC)
What do you mean "bendy", have you not heard of foils, epee or sabers?

As for titanium, I think it's too brittle, any serious impact might shatter or break it.
banazir
Feb. 24th, 2006 01:55 am (UTC)
Blade strength and metal folding: exponential growth in number of layers
Folding swords more than 30 times or so is generally useless, as the blades are typically less than 2^30 molecules thick.
230 is an upper bound - more than 12-15 is probably useless (though I've heard 10).
Part of the problem is that the steel in Connor MacLeod's Masamune katana in Highlander was said to have been folded "200 times", and that got stuck in the popular imagination. If that was lg 200 ~= 8, it would make fine sense; otherwise, how was she even able to tell?

In my understanding, titanium is far too rigid to make swords out of, but I also never really understood why swords had to be bendy anyway.
It wouldn't be rigidity but brittleness, as wudu_wasa said. I asked the student whether this was the case; he cited eyeglass and bicycle frames as an example of flexible and light but strong titanium products, but I am not sure that these are not made from alloys.

Full disclosure:
IANAS (I am not a swordsmith)
IANAM (I am not a metallurgist)

IANAM either. My dad (a physical chemist) confirms that solid titanium is superior to steel for strength-to-weight ratio and stress resistance in general.

From the Wikipedia entry on titanium:
Titanium is as strong as steel, but 43% lighter; it is 60% heavier than aluminium, but twice as strong; however these numbers can vary a little because of the use of different alloys. These properties make titanium very resistant to the usual kinds of metal fatigue.

When in a metallic powdered form, titanium metal poses a significant fire hazard and, when heated in air, an explosion hazard. Water and carbon dioxide-based methods to extinguish fires are ineffective on burning titanium; sand, dirt, or special foams must be used instead. Salts of titanium are often considered to be relatively harmless but its chlorine compounds, such as TiCl2, TiCl3 and TiCl4, have unusual hazards. The dichloride takes the form of pyrophoric black crystals, and the tetrachloride is a volatile fuming liquid. All of titanium's chlorides are corrosive. Titanium also has a tendency to bio-accumulate in tissues that contain silica but it does not play any known biological role in humans.

I'll see if I can find about about the fracture susceptibility.

--
Banazir
taiji_jian
Feb. 23rd, 2006 10:13 pm (UTC)
Bill, I'm pretty sure the military is using titanium / steel alloy in some of their combat knives. IIRC, the reason it is good is that it is more water resistant than good steel, while still being more "steel-like" than stainless steel.

I don't believe it would be good for a sword at all. First of all, it would probably be too light. Cutting through people (and concrete and steel and whatever) is accomplished by velocity, not by sharpness. The more tough your target material is, the more blunt your tools tend to be. (I.e., diamond-edged saw blades for cutting sheet steel are very TOOTHY, but not that SHARP.) IOW, you get diminishing returns from sharpness. You need your knife to be sharp, because it doesn't have a lot of leverage. The more leverage you have, the less difference the sharpness makes.

Second, there's the flexibility issue. I dunno exactly how stiff titanium is, not being a metallurgist, but my impression is that it's like a tougher version of aluminum. Light and stiff.

( 9 comments — Leave a comment )

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