Charpy toughness of historical swords?

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ButlerianHeretic

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I've done some searching online for Charpy test numbers for the steel used in good historical blades from the late middle ages or renaissance, but haven't found anything. Does anyone know or have links to such information? Or the Charpy toughness of a similar modern steel for comparison purposes? I have looked for 1055 and 1095 steel, but haven't been able to find that either.
 
Thanks, I have seen that. I was pleased to see that the better blades were in a similar range as reproduction swords at just under 60 Rockwell hardness. I'm curious about other qualities of these blades to get a better idea of "good-enough" values, in this case for toughness. I see a lot of people talking in absolutes and would like to cut through that to see find out what the qualities real-world blades were in an era when they were actually used in combat. Even grade 5 titanium (TiAl6V4) looks pretty good in comparison.

My suspicion/assumption is that even the best crucible steels of the era would be far more brittle when hardened to levels comparable to what is routine with modern steel, but it would be nice to know how much. I'm especially wondering how the tougher modern stainless steels used in some knives (from 440A,B,&C up through really high-tech stuff like CPM s35vn) stack up against historical carbon steel, especially in comparison to assertions that stainless steel swords will break. Certainly the best modern carbon steel alloys are far tougher than any stainless steel, but the best stainless steels are significantly tougher than many modern carbon steels too. And since all blade qualities are tradeoffs, then what is a good-enough value for relative toughness?

My curiosity is based on the context of designing a sword or a machete oriented toward a survival and self-defense role where minimizing required maintenance would be a big plus. It seems that the simplest way to establish a minimum value of toughness would be to determine the toughness of historical blades, but I'm having trouble finding any sources that address this. That is kinda unsurprising since these require destructive tests of valuable antiques and historical artifacts. Alternately, it would be nice to at least know what the toughness of steels commonly used to make swords and machetes are, but these are surprisingly hard to find too.
 
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From the graphs in the ASM metals handbook, for quenched and tempered carbon steels of carbon content typical of good swords of that time (about 0.6-0.7%), Charpy impact energies are 11-15J at room temperature. 0.8%C is 9J, and 1095 will be lower than that.

440C hardened to 57HRC, all of 2J. 440A should be about 8J.

440A should be OK as a sword steel. You should be able to get the hardness of 1055/1060 combined with the toughness of 1095, and reasonably good corrosion resistance.
 
I have a 440B kukri .That is an appropriate steel with greater toughness than 440C. All you need for a sword !
 
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440B has a higher carbon content than 440A. At the same hardness, one would expect it to be less tough. That's the way that low alloy carbon steels behave. I haven't seen Charpy energies for 440B and 440C, but expect them to be lower than for 440A. Izod V-notch energies are 3J, 4J, 5J (2, 3, 4 ft.lbs) for 440C, 440B, 440A.
 
many of the European blades were not heat treated at all during the Migration and Viking periods. Often, the hardness that was there came from phosphorus in the alloy.

However, when they were heat treated, it was within a range from about 50RC to about 54RC. That would be for arming swords and longswords and things in between.
They were springs, really. I don't have the reference data right at hand but I have read it and had a few discussions on the matter with people who did direct testing.

You could buy Tylecote and Gilmour
The metallography of early ferrous edge tools and edged weapons

it has much of the info you want for pattern welded blades.

kc
 
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Timo ,sorry my post should be 440C not 440A . Typo ,have corrected it !
 
mete said:
Timo ,sorry my post should be 440C not 440A . Typo ,have corrected it !
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People have made 440C work in swords, but I'd avoid it unless I really trusted the maker's heat treatment. 440B is safer, and should make for an excellent sword with ideal heat treatment, but I'd opt for 440A (or even 420HC) for the OP's suggested application. Even with carbon steels, you're getting into significantly reduced toughness when you're in the 440B carbon content range. "Survival machete" suggest not so easy to replace if you chip/snap it, so something that will dent or bend is better. I don't know which way 440B will go.

(440B, differentially hardened, might be pretty good.)
 
kevin -the professor said:
However, when they were heat treated, it was within a range from about 50RC to about 54RC. That would be for arming swords and longswords and things in between.
They were springs, really. I don't have the reference data right at hand but I have read it and had a few discussions on the matter with people who did direct testing.

You could buy Tylecote and Gilmour
The metallography of early ferrous edge tools and edged weapons

it has much of the info you want for pattern welded blades.
Click to expand...

Hardness measurements and metallography are relatively easy to find. Hardness testing is minimally destructive, and metallography only needs small samples. Toughness measurements (e.g., Charpy, Izod) need bigger samples, and it might not be possible even if you sacrifice the whole sword.

Another possibly useful book is Williams, The Sword and the Crucible.

Speaking of pattern welding, it should be noted that pattern welding can enormously increase toughness. Apart from having bands of tougher (but softer) steel/iron in the composite construction that are less likely to break, the welds between the layers tend to stop cracks from spreading from one layer to the next, delamination sucks up energy that would otherwise break the blade (OK, you get splits running along the blade, but it stays in one piece), etc. Some nice picture of this kind of thing in https://e-reports-ext.llnl.gov/pdf/238379.pdf
 
Steel age hardens.

Doesn't really matter when you are examining blades 50-100 years old, but it very much matters when checking blades that are 500 years old.

Best Regards,

STeven Garsson
 
As far as pattern welding goes, when I was first learning damascus my first two blades were 5160 and 1018 in a 3:2 ratio. Differential hardened them and did not temper them at all, and mine has survived twenty+years of use and hasn't broken, and holds a decent edge. PW blades can do some interesting stuff.
(Note:I'm not advocating that as a process, just sayin' the blades that it produced with those steels are tough, sharp and servicable.)
 
Timo Nieminen said:
References? This would be really important when looking at old steel weapons.
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Conversations with Kevin Cashen, Anna Feuerbach, Hank Reinhardt and Philip Tom.....if you want scholarly written references on this subject, that isn't my forte'....I have nothing to do with old steel weapons....just modern ones.

The advice from every qualified person that I have ever spoken with is that even in the case of junker blades with no substantial intrinsic value was that if they were old, they were more likely to snap than bend(WRT Japanese weapons) and that the fragments that had been examined were harder than what was expected.

Work hardening can be a factor as well, when swords do bend, and then are bent back.

Best Regards,

STeven Garsson
 
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I would also like some references. Not that I deny it but I would like to see the details What are the changes , how significant are they.
 
mete said:
I would also like some references. Not that I deny it but I would like to see the details What are the changes , how significant are they.
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Then find some.

Am not being a smartbutt here....the conversations satisfied the questions at the time, you are sure to have different questions and will require different references to back up anything discussed, and I have neither the time nor inclination to do that work for you.

I just provided my sources, three are still living. Feel free to contact them. Am sure it will be a great conversation!

Best Regards,

STeven Garsson
 
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I don't think you appreciate how much time I spend researching .There's always stuff to learn !
 
mete said:
I don't think you appreciate how much time I spend researching .There's always stuff to learn !
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Talk to Kevin, or Philip...they are living it....every day.

More than always stuff to learn, at some point you have to realize that in your life, the greatest effort that you can put through, you will only scratch the surface.

The internet helps greatly as an aggregator of content that all entirety has posted or posited....but still....a drop in the bucket.

Steel is a mistress that will allow no one mortal full understanding, not at this time, but maybe someday there will be some Neo-like person who can explain that which has been previously unexplainable.

Best Regards,

STeven Garsson
 
well, some swords actually soften over time.
http://pueblo-ops.cz/wp-content/uploads/2013/01/10.11648.j.am_.20130204.12.pdf

metal aging leads to recrystallization, grain growth, and softer metal in bronze and iron and steel. maybe a different reaction for hardened steel. But, age hardening is typically used in the literature as a synonym for precipitation hardening. This occurs over 10 or so hours at high temps. Maybe there is low temp precipitation hardening, but then it would be in competition with the aging process and relaxing of steel.
 
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