about swords, iron/steel and some physics

[XorX]

so, for not hijacking the "roman edged weapons" thread any more, I begin a new one here.

I think there is some confusion about steel / iron, ist`s use and treatment.

Bryan wrote: "Jürgen,

I wasn't referring at all about hardening steel, or more specifically iron, since steel making reliably was spotty at best. What I was referring to is the flexibility of swords, which is not just a matter of carbon content, but from my understanding, a matter of heat treatment (quenching and tempering). I understand and agree with you that most swords of the time period wouldn't have had this treatment. But as someone knowledgeable about sword making you can't argue that what Philon was describing wasn''t a sword that had obviously been tempered, regardless of its steel content. With that description, you can't come to any other conclusion. So whatever you previously thought of, know now that while it may not have been prevalent, tempering in some way, shape or form, existed in the 2nd Cent. BC time period, at least by the Celts."

heat treatment of steel (I will use the word steel in the whole, because all we talk about here is steel by chemical definition: "an alloy of iron with other elements, mainly carbon") only makes sense and has an effect if there is an amount of carbon higher than ~ 0,4% contained in the steel. Steel with carbon below that can be quenched and tempered as often as you want, there will be no effect of hardness, flexibility or anything else.
I sure agree that what Philon describes here is a blade which was correctly heat treated, but this effect is not possibly in a blade made in a composite construction with mainly soft steel used and steel with more than 0.4%C used only for the cutting edges. such constructions and weaker ones are the mass of the blades examined for a long timeframe.

about pattern welding and other "visible combinations of different steels": I`d never say that pattern welding was a step forward in blade-making in the sense of an "evolution". Patterns as we see them in mass in the 3rd-5th century roman blades and later in 6th-8th century germanic spathae dont make a blade stronger. they make them more beautiful and fancy. 8+)
a blade core constructed of several very tiny pieces in a "chaotic" order with many possibilities to break due to welding faults is not a step forward in a technical sense. it`s just nice

Bryan also wrote: "Where are you getting info that Roman swords weren't flexible? Is this a guess or based off of archaeological remains?"

well, you can`t take originals and bend around a bit to see what happens, but I`ve made some reconstructions the last years using different original shapes and different proven composite techniques and period materials e.g. different welded steels. tests showed that these blades perform exactly as physical laws and the characteristics of the materials let suppose (see: "Die römische Armee im Experiment")

there are for sure possibilities of composing different steels to a blade which perform better than others, but all of them have their limits. it`s a big difference between blades made in modern mono-steels and ones made from welded steels.

Bryan also wrote: " Most swords are not purposely made stiff (mainly thrusting swords such as estoc or rapiers), so this level of springiness and flexibility would be the norm for well built swords and sabers throughout the ages. Flexibility of this type is absolutely necessary for a good cutting sword, and the various gladii were known to be cut and thrust swords with a well forward center of balance."

This level of springiness was not the norm up to the 10th century, it was something special. the known forms of composites to make blades are mostly not able to provide such flexibility, but a blade made from a single bar of quite high-carbon-steel is. because it can be hardened and tempered. there are some blades of this type throgh the ages, but it was never a mass of them.
mass production of single-bar-swords begins as late as ca. 900 a.d.. a good example are the non-patterned ULFBERHT-blades

flexibility is not necessary for the use of a cutting sword. best example everybody knows of are traditionally made katana: they have a superhard edge, tough sides and a soft core. when improperly used, they bend, some of them even crack in the cutting edge in such a cause.
there are some composites in katana blades which are a bit stiffer, but none of them provides flexibility like a spring. they aren`t even able to do so because most of the blade doesn`t contain enough carbon to get a proper heat treatment. springiness normally is achieved by hardening a complete bar and then tempering it.

So: no carbonno hardeningno temperingno flexibility

a low degree of flexibility can be achieved by work-hardening, which is in fact a work-strengthening, but in this way you can only do a treatment to very thin pieces. the core of a blade will stay ductile and the flexibility is quite limited.

about hardness, strength and flexibility:

technical definitions: hardness is the ability to resist against the penetration by another object
strength is the ability to resist deformation
flexibility / springiness is the ability to bend to some degree without plastic deformation
strength and hardness are a big contrast to achieve in a blade, that`s the main challenge in
making blades

these 3 physical abilities have to be combined in every tool /sword/..., but the one who makes an item is always limited by his material sources, his knowledge, finance, etc.,...

[Luka Borščak]

Good post man. But are you sure twisting the rods in the pattern welded steel doesn't serve a functional purpose? Straight rods in the blade might not stop the delamination, but if delamination/crack stumbles into a twist, it might stop there...

[Bryan]

so, for not hijacking the "roman edged weapons" thread any more, I begin a new one here.

heat treatment of steel (I will use the word steel in the whole, because all we talk about here is steel by chemical definition: "an alloy of iron with other elements, mainly carbon") only makes sense and has an effect if there is an amount of carbon higher than ~ 0,4% contained in the steel. Steel with carbon below that can be quenched and tempered as often as you want, there will be no effect of hardness, flexibility or anything else.
I sure agree that what Philon describes here is a blade which was correctly heat treated, but this effect is not possibly in a blade made in a composite construction with mainly soft steel used and steel with more than 0.4%C used only for the cutting edges. such constructions and weaker ones are the mass of the blades examined for a long timeframe.

See bold. Then the conclusion is the swords with iron blades with low carbon content couldn't be made to be flexible, nor could they be hard. So these might be the crappy swords even Polybius discusses that were commonly bending. Meanwhile, those iron blades that were case hardened on the edges, or pattern welded, or made with quality iron, and then heat treated, could be made to be flexible (as stated by Philon).

XorX wrote:
well, you can`t take originals and bend around a bit to see what happens, but I`ve made some reconstructions the last years using different original shapes and different proven composite techniques and period materials e.g. different welded steels. tests showed that these blades perform exactly as physical laws and the characteristics of the materials let suppose (see: "Die römische Armee im Experiment")

So other than your own recreations, how do you know that Roman era blades weren't springy? Any iron blade with blade edges that had been case hardened can have been tempered to make it flexible. As demonstrated in numerous finds, the carbon content of Roman swords and where the carbon was concentrated varied immensely, as would there quality of construction.

However, if you have a sword with proper steely iron makeup (which there is evidence of), how can you be sure it wasn't heat treated? It is because you just don't think a gladius needed to be flexible or is there something else? As previously stated, Philon knew all the way back in the 2nd Century BC that some people (Celts) considering a good sword one that was highly springy. Now considering that Celtic ironsmithing heavily influenced the Romans, and that there are numerous examples of Gladii with med. carbon blades, where are you getting the idea that the Romans didn't have the ability or desire to have any springiness in their swords?

XorX wrote:
This level of springiness was not the norm up to the 10th century, it was something special. the known forms of composites to make blades are mostly not able to provide such flexibility, but a blade made from a single bar of quite high-carbon-steel is. because it can be hardened and tempered. there are some blades of this type throgh the ages, but it was never a mass of them.

What were the Celts doing to their blades that allowed only them to have springy swords? Did not the Iberians also have the capability to produce well made swords? What about the great iron workers of Noricum (Iron Road), where the Romans are known to buy their iron for sword construction?

XorX wrote:
]mass production of single-bar-swords begins as late as ca. 900 a.d.. a good example are the non-patterned ULFBERHT-blades

From the 3rd Cent BC to the 1st Cent. BC, 40,000-125,000 Romans would serve in the legions every year. Every one of them was armed with a sword. An equal or higher amount of Latins and Italians served yearly with the Romans, they too were all armed with swords. Meanwhile, their enemies, the Celts, the Iberians, the Hellenics, etc., most of all the warrior types also had swords. Are you stating that the ancients didn't have the ability to mass produce swords?

In a case of the Romans, when by the 1st Cent. BC, the state was responsible for providing arms, I doubt the standard gladius issued out would be a perfected constructed sword, with a perfect carbon content and perfect heat treatment. It didn't need to be. However, if a soldier wanted quality, they could just pay for it themselves. In that case, the technology to make quality swords had already existed.

XorX wrote:
flexibility is not necessary for the use of a cutting sword. best example everybody knows of are traditionally made katana: they have a superhard edge, tough sides and a soft core. when improperly used, they bend, some of them even crack in the cutting edge in such a cause.

there are some composites in katana blades which are a bit stiffer, but none of them provides flexibility like a spring. they aren`t even able to do so because most of the blade doesn`t contain enough carbon to get a proper heat treatment. springiness normally is achieved by hardening a complete bar and then tempering it.

The techniques used to make katana blades were completely different then weapons grade iron weaponry in ancient Europe/Mediterranean area of the classical period. The iron material (iron sand) was different, different furnaces (Tatara), different blade design (sandwich different grades of steel), and lastly, used completely differently. So I don't expect two different sword types, separated by a 1,000 years and half the distance of the world to be similar.

XorX wrote:
So: no carbonno hardeningno temperingno flexibility

Did examples of Roman swords not have carbon? Yes. Is there evidence that they didn't case harden? Yes Did they not temper? Yes If they did all those things, and they did, then they were flexible. Just like Philon says.

[Luka Borščak]

XorX's post is a bit of a generalization of course, true for most ancient swords. Can anyone post the Philon's citation about springy swords? I have no doubt technique for heat treating existed and was used in La Tene and Roman cultures, but since they didn't temper swords (at least everything I read about ancient swords states that they didn't know how to temper) I doubt they tried to harden their swords deep into the steel because without tempering such swords would be hard, but likely to crack which is far worse thing to happen in battle than bending. So it makes much more sense that they tried to harden only edges of the blades or shallow outer layers of the blade. How springy would such a sword be? Also, does anyone knows how work hardened swords made of phosphorus iron behaved when flexed? I know phosphorus iron can work harden quite well, but I don't know about spring qualities of such blades...

[Bryan]

Luka wrote:

XorX's post is a bit of a generalization of course, true for most ancient swords. Can anyone post the Philon's citation about springy swords? I have no doubt technique for heat treating existed and was used in La Tene and Roman cultures, but since they didn't temper swords (at least everything I read about ancient swords states that they didn't know how to temper) I doubt they tried to harden their swords deep into the steel because without tempering such swords would be hard, but likely to crack which is far worse thing to happen in battle than bending. So it makes much more sense that they tried to harden only edges of the blades or shallow outer layers of the blade. How springy would such a sword be? Also, does anyone knows how work hardened swords made of phosphorus iron behaved when flexed? I know phosphorus iron can work harden quite well, but I don't know about spring qualities of such blades...

Heat treatment methods like tempering must have existed if the level of springiness is true of Celtic swords, as told by Philon.

"[Celtibernians] grasp the hilt [of their swords] in their right hand and the end of the blade in their left; then, laying it horizontally on their heads, they pull down at each end until they touch their shoulders [each end]. Next, they let go sharply, removing both hands. When released, [the sword blade] straightens itself out against and so resumes its original shape, without retaining a suspicion of a bend. Though they repeat this frequently, the sword remains straight."
Philon of Byzantium, βελοποιικά (Belopeika), 4.71

This is sourced from Nic Field's Warlord's of Republican Rome and can also be found in subtle translation differences in several other secondary sources. Unfortunately, I'm still unable to find an online copy of the original text.

[Dan Howard]

Connolly wrote about personally witnessing a 2000 year-old sword dredged from Lake Neuchatel that could be "bent almost double and then flex back" (Greece and Rome at War, p.115). The best book on this subject is probably Pleiner's The Celtic Sword.

[XorX]

Bryan wrote:
" Meanwhile, those iron blades that were case hardened on the edges, or pattern welded, or made with quality iron, and then heat treated, could be made to be flexible (as stated by Philon)."

no, they could not. physics of the construction stand against that. if you have, for example, a simple soft steel core with welded-on high carbon cutting edges which are properly hardened and tempered, the whole weapon will stay bent after a wrong hit. the edges alone would be flexible, but the soft, ductile core will not allow that. the same about pattern welded cores containing mostly soft steel and a grain structure destroyed or interrupted by the grinding of the blade.
to get a flexible blade you have to use a single bar of steel with the right carbon content and forge the blade out of this piece, then harden and quench it.
the main reason for the use of high carbon steel just on the edges of a blade is simply money: it`s expensive in time, manpower and resources to make steel (mainly by carburisation )

Bryan wrote:
"However, if you have a sword with proper steely iron makeup (which there is evidence of), how can you be sure it wasn't heat treated?"

I`m sure they were heat treated. but the known composites don`t allow springiness. it`s simply physics... the edges of a blade can be as flexible as modern vehicle springs, but if these narrow stripes are welded to a core of ductile material, the whole thing will bend. heat treating is no guarantee for flexibility. it`s a guarantee for hard edges that won`t break.
I believe for sure that smiths used heat treating techniques as early as the 5th. century b.c, but they had no intention (and not the needed mass of high carbon steel) to create a mass of springy blades. there were always some outstanding blades with these abilities, but the finds say that much more had a composite construction in some form.

Bryan wrote:
"What about the great iron workers of Noricum (Iron Road), where the Romans are known to buy their iron for sword construction?"

well, if we knew that exactly... in fact, we do not know anything about the ferrum noricum and what made it so special. would be really interesting to find out more here!

Bryan wrote:
" Are you stating that the ancients didn't have the ability to mass produce swords?"

sure they had!. but they didn`t have the ability and the need to produce single-bar-high-carbon-content swords. and the finds show that most of the blades had some sort of composite construction. even high status examples as the "sword of Tiberius".

Bryan wrote:
"The techniques used to make katana blades were completely different then weapons grade iron weaponry in ancient Europe/Mediterranean area of the classical period. The iron material (iron sand) was different, different furnaces (Tatara), different blade design (sandwich different grades of steel), and lastly, used completely differently. So I don't expect two different sword types, separated by a 1,000 years and half the distance of the world to be similar."

I didn`t say that a katana and imperial roman swords are similar. but you said before that a cutting weapon has to be flexible. a katana is the proof that this is not true.
by the way: the techniques used are quite similar...: steel made in a furnace, refined and separated according to carbon content, then assembled to a composite of some type and heat treated...
the japanese just began using these techniques 1000 years later ;-)

Bryan wrote:
"Did examples of Roman swords not have carbon? Yes. Is there evidence that they didn't case harden? Yes Did they not temper? Yes If they did all those things, and they did, then they were flexible. Just like Philon says. "

they where flexible... some of them... not as many as we would like...
all of the composites using a mass of low-carbon steel don`t have the ability to get springy as a whole thing. may the edges be as good and well-made as anything...
and most of the finds are composites, no single-piece blades (which is misleading because these also were made of several 1000 layers of material due to the process of refining)

Luka wrote:
"Good post man. But are you sure twisting the rods in the pattern welded steel doesn't serve a functional purpose? Straight rods in the blade might not stop the delamination, but if delamination/crack stumbles into a twist, it might stop there... "

i think the main problem is that the strainy structure of the rods always is cut through by grinding the surface, fullers, etc... that makes such a rod weak because all these small welds lie open in different directions to the ways of power in the blade.
and except from that: see the mosaic patterns from Nydam and Illerup which have clearly no technical sense...

[Bryan]

I read Pleiner's The Celtic Sword based on one of your previous recommendations. I think you need a PhD in chemistry to understand that book. Nearly 95% went right over my head.

[XorX]

Connolly wrote about personally witnessing a 2000 year-old sword dredged from Lake Neuchatel that could be "bent almost double and then flex back" (Greece and Rome at War, p.115). The best book on this subject is probably Pleiner's The Celtic Sword.

and how many of the blades from that place don`t flex?...

there were always some extraordinary pieces, but not in mass

[Bryan]

Connolly wrote about personally witnessing a 2000 year-old sword dredged from Lake Neuchatel that could be "bent almost double and then flex back" (Greece and Rome at War, p.115). The best book on this subject is probably Pleiner's The Celtic Sword.

and how many of the blades from that place don`t flex?...

there were always some extraordinary pieces, but not in mass

How many blades have you tested? Why do you think that Roman swords, or Celtic La Tene II and III swords known to be slashing swords, reported by Philon to be tested for springiness, weren't springy by and large? Is there some source that you're using that reports this info?

[Dan Howard]

and how many of the blades from that place don`t flex?...
there were always some extraordinary pieces, but not in mass

In every culture you find crap weapons, good weapons, and exceptional weapons. I'm afraid that I no longer know what the point of this thread is.

I didn`t say that a katana and imperial roman swords are similar. but you said before that a cutting weapon has to be flexible. a katana is the proof that this is not true.

Actually it just shows how crappy the katana generally was. The Japanese had to place so much emphasis on technique because of how easy it was to damage their blades. A sword with more flexibility is much more forgiving of poor technique.

[XorX]

How many blades have you tested? Why do you think that Roman swords, or Celtic La Tene II and III swords known to be slashing swords, reported by Philon to be tested for springiness, weren't springy by and large? Is there some source that you're using that reports this info?

well, in most of the museums I know, you`re not allowed to grab all the blades and bend around a bit..., so I`ve tested none.

I think most of them were not springy because most of the ones I know which are examined or where the construction technique is visible are built in a manner that does not allow springiness. total springiness and total hardness of a blade stand contrary. the can`t be achieved in one blade. it is always a compromise. it depends on many factors to which side this compromise tends in a blade.

my main source for this claim is the archaeological evidence, the other is the report of, I think it was Tacitus?, I`m not sure about that, who sayd that Celts in a battle against romans had to rebend their bent slashing swords in battle.

Dan:
what we define as crappy today must not have been seen so in the times when the pieces in discussion were in use. The question should be: why did they produce so many "crappy" swords when they had the abilities to produce "better" ones?
my guess is: it was about money in the widest sense, as I said some posts before. the infrastructure (sources of excellent ores, specialised furnace technique, specialised craftsmen, extra energy for carburisation of softer steel e.g. charcoal, knowledge!! not only by some specialists, but by a large range of craftsmen,...)needed to produce the needed amount of the right steel is much more expensive than finding a compromise that works for the mass

it`s also interesting that in the time when Japanese began producing "crappy" swords, in europe the techniques had developed to a mass production of "springy blades". it`s thought that this was based on more effective furnace techniques used from this time onwards.

the point of this thread: I see a tendence, when discussing weapons, to use modern terms of "quality" on the ancient pieces. I think that is the wrong way. we should discuss the original items we have, examine much more of them chemically and from a physical point of view, make more reproductions of different types of blades in different constructions using period material and test them in experiments. then we can tell what the blades were able to do, not what they should be from our modern view.
this can help to rise our knowledge about how fighting was done, in which ways the weapons can have been used,...
I personally don`t rely totally on some single written sources because we never know if these describe the norm or something extraordinary.
I would not say that Philon or Tacitus or Erhart told fairytales, but we don`t know their sources, their special knowledge of blademaking, their intentions....

by the way: happy new year :-)

[Crispvs]

As someone who is certainly not a chemist I have found this fascinating thus far. There is just one small contribution I think I should make:

"high status examples as the "sword of Tiberius"."

The 'Sword of Tiberius' is not a high status weapon. The apparent richness of the scabbard led art-historical types to assume it was a gilded presentation scabbard decorated with specially made portraits of Tiberius which must therefore have been one of a limited set of 'presentation' swords in special scabbards, perhaps even presented by Tiberius himself. Unfortunately the reality is a little less glamorous. The scabbard is actually made from tinned brass, like so much other ordinary Roman military kit and the portraits are stamped, rather than individually worked, just like plenty of other known pieces of Roman sword scabbards which have clearly been 'mass produced' by being stamped (just like plenty of portraits of Tiberius between a pair of cornucopia which have been stamped into belt plates). Several surviving scabbard parts from Vindonissa can actually be shown to have been made in the same formers as each other. It was only the apparent richness of the scabbard to untrained eyes which led to it being dubbed 'the Sword of Tiberius' and being awarded the status of a high status item, rather than the perfectly ordinary item it really is. Sadly the BM have yet to update the card in the cabinet it is housed in, even though staff there tell me that they are well aware of the fact that it is not a high status weapon.

Sorry to pull this excellent threat OT, but I felt it should be said. As far as I know, we do not have an identifiable example of a high status Roman sword to check the composition or quality of. In fact, as far as I know, the only sword which can be identified as having belonged to an officer (let alone a general) of any ancient army was the one from the siege mine at Dura, and that belonged to a Persian officer. :neutral:

Crispvs

[Dave G]

https://www.youtube.com/watch?v=ngjMtzJ6xgQ

I thought this may be of interest here when referring to bending blades, though it deals with bronze weapons and not iron/steel ones.
Couldn't think where else to post it on it's own.
Surprisingly effective at cutting too.

[Alanus]

I don't know anything about "crappy" Japanese swords. I do know the Japanese didn't have great swordsmiths until a Chinese princess went to Japan during the Tang Dynasty. She brought two mainland smiths with her.

Here's a little information about early steel swords made during the Qin Dynasty and early Han Dynasty. And I would think that a small bit of knowledge of their techniques might help this thread, if simply to let everyone know how crappy these swords were. The earliest-- c. 220BC to the Year Zero-- were "standard" folded steel with anywhere from 30 to 50 refinings. As such, the 1st refining resulted in 2 layers, the second refining being 4 layers, so that by the 10th refining the carbon content was distributed within 1,024 layers of steel.

Unlike Roman and Celtic swords, we have precisely dated Chinese swords because many of them contain historic inscriptions. By the beginning of the 1st century AD, the swordmaking process was refined. A typical example is a jian forge-welded in 3 sandwiched plates ("sanmei"), dated by its inscription to AD77, plus the words "forged to 50 refinings." Here is a cut-away illustration of the analyzed blade:

[attachment=11521]cross2.jpg[/attachment]

The central plate extends out as the cutting edge, and it's 0.7 to 0.8 % carbon steel.
The two sandwiching plates have steel layer zones consisting of 0.4 % and 0.6 to 0.7 % carbon (the purple and white zones respectively).

During the 1st century AD, the Chinese began differentially heat-treating, and the highest quality ones were clay-tempered at night using only the forge as a light source. Here, at least, is a little "meat" on the physics of swordmaking, not just conjecture. I would think swordmaking in Europe paralleled that of the East, so hopefully the breakdown of this sword has value.

Interestingly (or not), the majority of Type 1 Late Sarmatian swords used from 100BC to AD100, appear to be of Chinese manufacture, and almost all of the ones recovered have jade pommel and scabbard fittings, including the scabbard slides. I have been collecting examples of these crappy swords for 10 years, and they come from craftsmen who have been making them since 200 BC.