The sound of steel?

[Dave Rogers]

I've been noticing something that's got me curious about the differences between various swords I've handled. Being a newbie and neither a metallurgist nor a swordsmith perhaps somebody can enlighten me: Does the sound that a sword makes when struck mean anything?

For example... Some swords, noticeably (for me to date) those that are less costly, both sharps and blunts, if you tap the blade with something there's just a dead "thak" or "tink" sort of sound. But the better swords I've handled like the Albion Baron sharp or Liechtenauer blunt... if you tap on those blades with something they'll sing like a tuning fork. In fact they ring for quite a long time with a bright clear tone.

First: does this mean anything? What about the steel makes it ring or not? Is there something inherent to the metallurgy or treatment or geometry of the steel that makes this difference? Moreover, is this something that is useful in judging the quality of a blade, or hardness/softness of the steel? Or is it just a feature that may or may not be present across a spectrum of various blades, having nothing much to do with the composition or quality of the steel, or the length or geometry of the blade? Or is this a dumb question?

Regards,

Dave

[Stacy Clifford]

There may be something about the steel that affects the tone I'm sure, but it also has a lot to do with hilt construction. The cheaper ones tend to have poorer and looser construction which dampens the vibration of the blade, while the better ones have a tight fit between all the parts. It's like the difference between a tight guitar string and a loose one. My Lutel sings like a nightingale, it's beautiful to hear.

[Parker E. Brown]

The tone of the steel is likely going to be related to how well the sword blade was hardened and tempered. Hardening steel involves heating it to a high temperature where it’s in its austenitic crystalline phase and then quickly cooling it through quenching (the cool part where the smith plunges the steel into cool liquid). When it's quenched, a part of the austenite composition is transformed into martensite that is very hard, but very brittle. At this point, the blade is about as fragile as glass. I've done cool experiments where I have hardened a piece of steel and then dropped it to see it shatter (probably not the safest thing to do). This would obviously not do for a sword blade, so you have to temper the steel by reheating the blade to a lower temperature, thus taking away some, but not all of the hardness. The result is steel that holds an edge, but is still flexible. All this is to say that after moving and arranging the steel's crystalline structure through heat, I would have no doubt that the steel's sound when struck would be better when the heat treatment is done properly.

[Dave Rogers]

The tone of the steel is likely going to be related to how well the sword blade was hardened and tempered.
[...]

Thanks, yes, that makes a lot of sense. It almost has to be some indication from the treatment of the steel.

And thanks Stacy... I hadn't considered whether there's a dampening effect from the hilt. That's an interesting complication.

[Brandon Paul Heslop]

But the better swords I've handled like the Albion Baron sharp or Liechtenauer blunt... if you tap on those blades with something they'll sing like a tuning fork.

That's what they called a "singing sword" historically.

-B.

[Chris Ouellet]

The sword must vibrate to create a sound, the physics of it is not that dissimilar to stringed instruments. The strength of your tap gives the amplitude and where your hand holds the sword is necessarily a node as waves travel back and forth through the steel. It's a second year physics problem to describe how the waves travel based on the material properties such as the young's modulus. Good swords are generally more flexible than crappy ones so they maintain a higher amplitude vibration for longer, they do in fact "sing".

[Vincent Le Chevalier]

The strength of your tap gives the amplitude and where your hand holds the sword is necessarily a node as waves travel back and forth through the steel. [...] Good swords are generally more flexible than crappy ones so they maintain a higher amplitude vibration for longer, they do in fact "sing".

Actually I don't think your hand automatically creates a node. The grip of a human being is far from being rigid and tight enough to do that. What it does is dampening the vibrations where the sword is held.

However, a majority of good swords have one primary node of vibration located in the hilt near the cross (the so-called 'harmonic balance'). In that case the dampening effect does not happen because there is little vibration around the hand in the first place, and the vibrations will last longer.

To sum things up, quality swords sing because the hilt is tighter, and the hand does not dampen the vibrations. Then, the tone of the sound is primarily related to the stiffness of the blade, which itself is a function of cross-sections and heat treatment.

[Chris Ouellet]

The hand is much more rigid than the junction between hilt and blade it is the fixed point about which the blade rotates. While there's a change in Young's modulus going from a free modulus to a constrained modulus at the hilt this isn't as significant as the hand.
You definitely do not want the vibrations in the sword to dampen in the hands, that causes discomfort and even pain.
I don't otherwise disagree with what you've said Vincent.

[Vincent Le Chevalier]

Any freely rotating point such as the cross is not a node and can't be. The hand is much more rigid than the junction between hilt and blade it is the fixed point about which the blade rotates. While there's a change in Young's modulus going from a free modulus to a constrained modulus at the hilt this isn't as significant as the hand.

There certainly can be a node at the cross, just like there is a node on the blade. They are there if you do not take the hand into account (light grip). When I try to grip my swords by the pommel and make it 'sing' it just does not work well unless my grip is very light, I believe, I'll have to check again later. This would be due to the fact that my hand is preventing the sword from vibrating in its first proper mode...

[Chris Ouellet]

You're absolutely correct, there can be a node anywhere along the material. My statement was wrong, I meant to say: the hand being a fixed point of rotation is necessarily a node. I wrote that quickly and 2nd year was a long time ago.
If you put your hand on the spot where a natural anti-node occurs then the vibrations will be severely damped.

[Vincent Le Chevalier]

Cool, we're on the same line then

[Vincent Le Chevalier]

After some further experimentation, there seems to be more about it than just the blade...

I tried again with my swords and it seems that the long-lasting tune is in fact produced by the quillons. If I hit the swords while leaving the quillon free, I get a long sound, whereas if I hit the sword with the forefinger layed flush along the quillon, the tune quickly disappears. Just hitting the quillon also produces a long lasting sound.

I think there is some form of resonance going on between the blade of the quillons when the hilt is tight, and the dimensions appropriate, which explains that some swords seem to sing more. Even though the vibrations of the blade are more noticeable, they are not necessarily what we hear, because their frequency is too low. On the other hand the blade is "airing" the vibration of the quillons, if the quillons vibrate at one of the proper frequency of the blade.

All of this is probably not relevant to combat application, but fun

[Adam Bodorics]

Steel quality and blade cross-section surely has something to do with the sound of the sword, but the nature of it (dull short THUNK versus sharper longer ZIIIING) depends on the hilt. I can make mild steel sing and I can make tempered spring steel stay silent, though I prefer a VERY tight assembly - which has a beautiful sound.
...
BTW, it has an indirect connection to fighting - if we could totally understand this effect, we could much better judge the current quality of our swords without professional methods - if one of my swords start to go THUNK, I put it down instantly as it shows that the hilt came loose.
I'm almost totally sure that close-to-critical cracks alter the sound somehow, so learning to recognise that alteration would be quite useful.

[Dave Rogers]

After some further experimentation, there seems to be more about it than just the blade...

I tried again with my swords and it seems that the long-lasting tune is in fact produced by the quillons. If I hit the swords while leaving the quillon free, I get a long sound, whereas if I hit the sword with the forefinger layed flush along the quillon, the tune quickly disappears. Just hitting the quillon also produces a long lasting sound.

[...]

All of this is probably not relevant to combat application, but fun

That's an interesting observation. I'll have to go back and test mine again, as I hadn't noticed that particular thing.

And thanks Adam... also an interesting point.

One practical application for the question was really about whether or not the sound of the sword means anything useful... that is, if you pick up a sword you aren't familiar with-- intending to use it-- aside from the basic balance and feel, does the sound it makes tell you whether the sword is of good or bad quality? Say... on those days when the battle has gone chaotic, you've lost your sword so you're hastily scrounging around among the severed limbs and castoff equipment and there's two swords to pick from... is that a criteria that matters? Gotta think fast because the enemy infantry is rallying for another charge...

[Derek Noble]

It was said earlyer that the heat treating of the steel makes a diferance. The heat treating and tempering are definetly part of the cause of the sound that comes off a blade, and its quality. However the heat treating alone is not the only cause, and gauge of the quality of steel. Steel, is mostly iron, with carbon, and some very small quantity of other things that have little value. If you where to heat treat a low carbon steel (IE, AISI 1020, .20% carbon) the result would be nothing (no change). In the case of plane "carbon Steel" its hardness is depending on the Carbon. It takes about .30%-.40% carbon to harden steel, unless other elements are added. Anyway the more carbon the harder it "can" get. So a cheaper blade is usaly made with softer less exspensive lower carbon steel. Though the sword with the sharpest ring may not be the best depending on your use. Because a harder steel blade is usaly a more fragil one. The geometry and sturdyness of the gaurd and grip I am sure makes a differance too. But if I am buying a knife usaly a chefs or cooking knife, or checking its quality, the sound is one of the best ways to test for steel quality and hardness, aside from doing a rockwell hardness test.