Clarification on the quality of Nihonto blades

[Ninja]

Hi @ROKUJURO and thanks for Your reply!

 

To answer Your question, of course not, they are two different things!

[mas4t0]

Many of the terms used by Jean are terms of art, which may not be fully understood by everyone reading without some further clarification.

 

I wrote a bit (hidden below), but it was growing too long so I thought it better to find some sources to link to.

 

Brittleness

Brittle and Ductile Materials

Ranking Toughness of Forging Knife Steels

 

Spoiler

You'd probably be best to ask your friend to elaborate, as his statements are quite vague, it's difficult to address the underlying misunderstanding.

 

For instance:

 

"brittle and lose their edge easily"

 

A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a sharp snapping sound. Brittle materials are (relatively) stiff, hard and can be very strong, but what characterises them is that they break without bending. Nihonto are not brittle overall; when a blade breaks during cutting practice, it is generally due to a forging flaw or crack propagation due to stress cycling. Nihonto are known to bend on bad cuts, which is indicative of ductility (i.e. the opposite of brittle).

 

The edge is more brittle than many other swords on account of the higher hardness, so would be more prone to cracking and chipping, but less prone to edge deformation and with better edge retention. The extreme of this would be a Japanese Honyaki knife, if you were to drop one on a tile floor it would likely snap, like most Japanese knives they lose sharpness through micro-chipping of the edge; contrast with a soft stainless steel German kitchen knife (such as Wusthof or Zwilling) which can bend 90* without breaking and require honing before each use due to edge deformation. The way in which knives lose their edge is different depending on the hardness; the edge of a soft knife deflects, it rolls over, while a hard knife chips and becomes saw-like.

 

The strength of a material is its ability to withstand an applied load without failure or plastic deformation. Carbon fibre has (very) high (tensile) strength and is quite flexible, but you'll never see a carbon fibre component bent out of shape due to brittleness - it'll either spring back to its original shape (if the strain was within the elastic zone) or it'll fracture.

 

 

The toughness of a given steel is inversely proportional to its hardness (hardness can be exchanged for toughness by tempering). Of the steels in the graph below, I would guess that 1095 is likely the closest to the edge steel on a well made nihonto, and you can see how a decrease from ~63HRc to ~57HRc doubles the toughness (the energy absorbed before the material fractures). The graph is relating to kitchen knives, so the HRc numbers are higher and the toughness numbers lower than you'd want in a sword.

 

 

In the graph above you'll notice the huge defence between L6 and 1095.

 

If you're curious how an L6 katana performs:

 

 

[mas4t0]

I hadn't ever given it any thought, but when writing the above (with consideration of soft kitchen knives and the need for honing to align the edge) I realised that the hardness of Japanese swords is the reason why we don't need to re-align the edge when cutting. I wonder if the (historical) scarcity of leather in Japan maybe contributed to the demand for and development of swords which did not require stropping to maintain the edge?

 

To keep this post on topic, the edge staying aligned and not needing honing is the opposite of "losing the edge easily".

 

A link with photos to clarify what I'm talking about:

https://scienceofsharp.com/2018/08/22/what-does-steeling-do-part-1/

 

 

Here if you want to get deep into sharp (expect Scanning Electron Microscope (SEM) images of blade edges at 20,000x magnification):

https://scienceofsharp.com/home/

 

As an aside, which may be of some interest. I have several kitchen knives made from Hitachi Shirogami Steel, which is designed to be chemically similar to the edge steel of Nihonto (though Shirogami is completely homogeneous mono-steel). The steel sharpens very easily and takes an extremely fine edge, in fact I'd wager that I can get a keener edge with Shirogami than any other steel. Shirogami doesn't hold its edge as well as Aogami (which has additional Tungsten and Chromium) but Shirogami gets sharper and is both easier and faster to sharpen.

 

A video comparing Aogami (blue) and Shirogami (white):

 

 

[Baba Yaga]

If someone wants to geek-out this is interesting https://www.sciencedirect.com/science/article/abs/pii/S0925838812016283?via%3Dihub

 

[mas4t0]

On 7/8/2022 at 8:01 PM, mas4t0 said:

 

These are all trade-offs in the design of the sword and, with a sharp weapon, I'd generally prioritise agility.

 

Blunt force is very different. It's often a good strategy in boxing (for instance) to take two or more glancing blows in order to land one solid blow in return. Julio César Chávez vs. Meldrick Taylor (17 March 1990) is possibly the best example of this. Size and weight make a huge difference in blunt force, in fact one of best boxers of our generation recently lost in a big upset after moving up one too many weight classes and facing an opponent who was too big and strong for the difference in skill to carry the day.
 

Sharp and pointy things change that entirely, in the absence of armour you only need to touch the opponent to end his life. In a duel I'd rather have the agility to cut first than have the tip inertia to cut deeper.

 

All of that said, I'd always want a Japanese sword if duels, fights, etc were to begin with blades sheathed as opposed to blades drawn. A swordsman skilled in Iai will have killed his opponent with a draw cut before the opponent (armed with a smallsword for instance) has even begun to draw his blade.

 

 

To return to this point of agility Vs inertia and how easily people lose their lives when sharp/ pointy weapons are involved; there's a video circulating social media of an altercation (in a food court in Australia) where one man (holding a knife) swings at another man and makes contact with his neck...

 

The man noticed the blood streaming from his neck, collapsed on the floor, and died very shortly thereafter. It's a horrible thing to see.

 

I won't share the video here, for obvious reasons.

 

It really is important that (if possible) people get a little bit of experience in boxing, kickboxing, etc and learn a proper guard. If you do have to face someone armed with a sharp weapon, you'll probably get stabbed and cut either way, but a solid guard and some training will at least ensure you properly protect the neck and have some chance of survival.

This felt worthwhile to mention, but please delete if it's too far off topic.

[Baba Yaga]

On 7/9/2022 at 5:49 AM, ROKUJURO said:

A butcher knife can never be compared to a Japanese sword as the uses are very different. You would not compare an axe (with good edge retention in use) to a sword, would you?

 

I did the NRA sponsored certification Gun, Knife and Automobile "defensive" tactical classes. I guess they had to call it  "defensive" but it seemed offensive to me. LOL

The Knife fighting class was anything but martial arts to my surprise. I don't believe the NRA offers this anymore, it was 3 days.

[DoTanuki yokai]

It breaks but I think they are not weak if used right. 

[mas4t0]

Maybe this will be of interest too: this is about the best we can get (in terms of durability) with contemporary metallurgy while still having a true hamon.

 

 

[AntiquarianCat]

No disrespect to Clark or his impressive talents meant but there’s ample record of old swords being tested as strenuously https://markussesko.com/2019/08/27/destructive-sword-testing/

 

Note the case of how Yamaura Masao became famous and how they only finally ruined his sword after numerous strikes against an iron like Clark does. Seems to be a similar outcome as Clark’s suffered many large hagire from the same test. This is not to diminish the impressive talent of modern smiths just to note that first class smiths have been doing the same feats for centuries.

 

Markus Sesko’s book on this is superb and worth reading for anyone curious about what records show on old swords and their impressive breaking point https://www.lulu.com/shop/markus-sesko/e-tameshigiri/ebook/product-21700689.html

[mas4t0]

8 hours ago, AntiquarianCat said:

No disrespect to Clark or his impressive talents meant but there’s ample record of old swords being tested as strenuously https://markussesko.com/2019/08/27/destructive-sword-testing/

 

Note the case of how Yamaura Masao became famous and how they only finally ruined his sword after numerous strikes against an iron like Clark does. Seems to be a similar outcome as Clark’s suffered many large hagire from the same test. This is not to diminish the impressive talent of modern smiths just to note that first class smiths have been doing the same feats for centuries.

 

Markus Sesko’s book on this is superb and worth reading for anyone curious about what records show on old swords and their impressive breaking point https://www.lulu.com/shop/markus-sesko/e-tameshigiri/ebook/product-21700689.html

 

The differences are quantifiable and it's not really about the smith. With modern mill steel, the sword-maker only really needs to worry about the geometry of the blade and the heat treat (which can be very accurately controlled with thermometers, salt baths, etc). If you take a piece of mill steel and shape a blade on a belt grinder (stock removal), you'll have a perfectly forged blade (as the blank is pre-forged); so you can now make excellent swords (though of course not Nihonto) without being a smith.

 

It's also maybe worth noting that the blade used in the video above by Howard was defective. If memory serves correctly it had failed during heat treat.

 

The comparison is a little more involved to do properly, due to the laminated construction of Nihonto, but perfectly forged tamehagane (i.e. perfectly homogenised and with no forging flaws) is significantly lower in toughness than L6 at the relevant hardness levels. (I don't have a reference to hand for this).

 

It's also worth noting that perfectly forged was not the norm for Nihonto, but is the norm for mill steel (unless the smith folds, pattern welds or does something very silly with the steel).

 

Toughness is the ability of a material to absorb energy and plastically deform without fracturing. Toughness is the strength with which the material opposes rupture.

 

No Nihonto can perform as well under destructive testing as one of Howard's L6 blades (with identical geometry), due to the differences in material properties.

 

Fracture toughness testing is rigorous in a way that old school testing modalities were not.

 

The process is as follows:

1. Machining of a standard test specimen (typically a single edge-notched bend or compact tension specimen), which is notched in the area of interest.
2. Growth of a fatigue precrack by application of cyclic loading, usually at room temperature.
3. Attachment of displacement measuring gauges across the crack mouth
4. Maintenance of a stable specimen test temperature, typically the minimum service temperature of the component of interest
5. Application of a monotonically increasing load, whilst monitoring both load and crack mouth opening.
6. Breaking open of the specimen to allow detailed measurement of the crack front (occasionally, this happens during the test itself).
7. Calculation of the relevant toughness parameters.
8. Validation of the results.

As the toughness of the material determines the toughness of the sword (for a given geometry), we can compare the materials directly.

 

There was a thread recently where a member had a bohi carved in his (traditionally made) shinken, and consequently the blade was bending very easily. If the sword were made from L6, the additional strength would have prevented this.

[AntiquarianCat]

We do see quantified information in Yaso’s papers, in fact he found that Bizen to have comparable toughness to modern structural steels. I have not currently seen a paper on L6 and would be eager to see what they find. As for purity, well we can look at Yaso’s findings re Koto swords. The quality of the swords Japan admired certainly surprised me in terms of purity. I don’t know how they were able to do it.

 

If the L6 sword that got hagires from iron was defective then surely is there a video of a properly made one? I would just like to see what one of his swords at their peak can do.

 

Indeed bending resistance would be an absolute advantage of l6 but there are documented cases where l6 blades suffered severe edge damage from soft wood or even plastic jugs with the manufacturer insisting that’s normal performance and not a defect. Supposedly testers say L6 has accelerated edge wear relative to other swords they’ve used, the one from that video claims edge rolling prone, so while  not bending would be a boon, it may not be the most important trait. They were able to quickly straighten Masao’s sword after gouging a helm but a sword that’s edge rolled most of its monouchi wouldn’t be back in the fight anytime soon. A new alloy as those mishaps show does not guarantee it will be superlative, heat treatment and geometry seem to have mattered more.
 

I don’t deny the talent of modern smiths, it great that they innovate, I’m just saying there is both extensive evidence on old very aggressive torture testing, and scientific studies showing good old swords are competitive with what’s around today. I also have as of now not seen L6 studies or documentation, let alone any confirming L6 preforming beyond what historic first class works could do (bending nonwitshstanding)

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No Nihonto can perform as well under destructive testing as one of Howard's L6 blades 

Pardon my ignorance but the only video in this thread has the Clark develop Hagire from hitting iron. They did the same with the Masao and it didn't develop fatal flaws until repeated hits of the same type and had previously survived other destructive testing. The limited evidence I have points to non-inferiority of Masao.

Quote

With modern mill steel, the sword-maker only really needs to worry about the geometry of the blade and the heat treat (which can be very accurately controlled with thermometers, salt baths, etc). 

That is certainly an immense advantage from an industrial standpoint. But the method of manufacture being far more efficient does not tell much about performance. It certainly is a powerful argument for why Mantetsu because the far greater efficiency of manufacture were a more reasonable way to make gunto, but doesn't mean they outpreform all good swords; just that it makes it easier and cheaper to make a good sword.

[PNSSHOGUN]

Hi Juan,  the use of L6 steel by these companies is dubious at best as the benefit of L6 as a sword steel is entirely dependent on the quality of the heat treating. It can be argued L6 is worse than a boring old steel like 1060 when being mass produced. The reality is a basic through tempered sword made of modern homogeneous steel made in a matter of hours is just as strong, if not stronger, than a masterpiece requiring days or weeks of work from a top level smith using all his diligence.

[AntiquarianCat]

I hope I didn’t imply otherwise! I can certainly see the great advantage of industrial steel in production. Given what I’ve read about tamahagane production it seems that having good steel let’s you skip the most time consuming bottlenecks and go straight into geometry and heat treatment. If the smith’s skill is equal they can make more swords and eliminate a point of failure. That’s why if I would need a shinken I would want 1060/1095 both for cost effectiveness and because less risk of mistakes than if a company tried to recreate tamahagane.

 

Thats why I’m a bit surprised there wasn’t a bigger effort to make high end modern steel blades during the war. 

[PNSSHOGUN]

There was certainly a concerted effort that resulted in a number of different specialty steels trialed and used in various capacities. The issue is many were not suited to being used with traditional methods, not to mention as the war progressed priorities were certainly moving away from super sword steels!

 

• Mantetsu Hagane
• Gunsui Hagane
• Yasugi high purity Hagane
• Shinbu-To
• Stainless
• Army sword steel used in Zohei-To

 

[mas4t0]

Juan,

 

2 hours ago, AntiquarianCat said:

If the L6 sword that got hagires from iron was defective then surely is there a video of a properly made one?

 

No, there is not a video destructive testing a sword Howard would be willing to sell to a customer, why would you expect this? The video was made with a dead blade which was unsuitable for sale. In the full video the issues with the blade prior to destructive testing are fully detailed, along with the motivation behind the testing. I like it this way as (1) it sets a low water mark (i.e. you know with certainty that if you buy an L6 blade from Howard it will outperform the blade in the video) and (2) he didn't destroy a perfectly good sword.

 

2 hours ago, AntiquarianCat said:

I’m just very used to being asked for evidence every time I say something so I hope that habit rubbing off on me is not obnoxious. That said, I really do not see how some studies, preferably in journals wouldn’t help us.

 

By all means share any journal articles which you think are relevant, but this is hardly cutting edge stuff. What I've been laying out so far on this topic is very basic information you'd find in a textbook and in data sheets rather than in contemporary journals. I'm not sure which parts you want journal references for (the journals would be antiqued) or what you think they would help with. Are you wanting a journal article about Howard's blades specifically?! If so I'm not sure which journal would feel it worthwhile to publish such an article.

 

2 hours ago, AntiquarianCat said:

Indeed bending resistance would be an absolute advantage but there are documented cases where l6 blades suffered severe edge damage from soft wood or even plastic jugs with the manufacturer insisting that’s normal performance and not a defect. Supposedly testers say L6 has accelerated edge wear relative to other swords they’ve used so while  not bending would be a boon, it may not be the most important trait. They were able to quickly straighten Masao’s sword after hitting iron but a sword that’s edge rolled most of its monouchi wouldn’t be back in the fight anytime soon. A new alloy as those mishaps show does not guarantee it will be superlative, heat treatment and geometry seem to have mattered more.

 

I concur with John's answer but if you want something more technical I can elaborate further. If so, let me know your background and I'll try to adjust the answer accordingly; I have a tendency to give overly technical answers which irritate more than inform people.

 

2 hours ago, AntiquarianCat said:

Yes we do see quantified information in Yaso’s papers, in fact he found that Bizen to have comparable toughness to modern structural steels.

 

Your clue here is that the comparison is being drawn to structural steels as opposed to tool steels. Most structural steels are optimised for low cost (as a lot of material is used). Very few structural steels are quenched and tempered, A514 is one example and it's use is generally restricted to applications where very high strength is required in order to save weight.

 

Structural steels are hardly the gold standard for high performance. As I recall, tool steels are broadly speaking >5x the price per tonne of structural steels.

 

You can review the data sheets of the various alloys to better understand their properties. The historical destructive tests are not consistent (even when conducted with the same methodology), but the data sheets for the various alloys will tell you all you need to know.

[mas4t0]

2 hours ago, AntiquarianCat said:

Pardon my ignorance but the only video in this thread has the Clark develop Hagire from hitting iron. They did the same with the Masao and it didn't develop fatal flaws until repeated hits of the same type and had previously survived other destructive testing. The limited evidence I have points to non-inferiority of Masao.

 

There's a huge amount of other factors at play.

 

What has happened previously?

Was the metal already fatigued?

How heavy was the niku?

What was the cutting edge angle?

What was the diameter of the iron rod?

What was the chemical composition of the iron rod?

What was the magnitude of the momentum and kinetic energy transferred upon impact?

 

There are far too many variables to compare blades in a meaningful way (especially from videos and written accounts). It's far more worthwhile to compare the materials.

[AntiquarianCat]

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No, there is not a video destructive testing a sword Howard would be willing to sell to a customer, why would you expect this?

Yes I would. I am quite surprised that a high end maker does not carry out destructive testing. That was very much the norm in the past. Surely there must be more videos or tests out there to show off performance?

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 I like it this way as (1) it sets a low water mark (i.e. you know with certainty that if you buy an L6 blade from Howard it will outperform the blade in the video) and (2) he didn't destroy a perfectly good sword.

How can we know a test with great but unremarkable results sets a low water mark? For anything? Without any more information it could be the upper bound. It just seems a major assumption to say every sword preforms far better than the one in the video when we acknowledge there is no evidence.

Quote

let me know your background and I'll try to adjust the answer accordingly;

Medical research, ABD, I will straight up admit the math and engineering stuff will sail over my head (why else study something light on math), but the same principles of research should hold, and if I want to prove something I'm told document and test.

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You can review the data sheets of the various alloys to better understand their properties.

The steel is only one variable though, as the L6 edge rolling epidemic production swords have shows. Whatever it's theoretically capable of what we see, empirically is that Clark from the video with an excellent smith and the L6 oni with not so great. It's a range more or less consistent with other swords. Great swords and not so great swords, line always.

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There's a huge amount of other factors at play.

I agree, completely. Which explains the performance variations seen. I am just saying empirically the results we have range from that Clark to the Oni. Could there be above? I'm sure there is but right now I don't think there is enough evidence to say how much and how often with certainty.

 

Thank you by the way, very thought provoking discussion. I will think about your points tonight.

[mas4t0]

Hi Juan,

 

12 hours ago, AntiquarianCat said:

Medical research, ABD, I will straight up admit the math and engineering stuff will sail over my head, but the same principles of research should hold, and if I want to prove something I'm told document and test.

 

I'm not trying to prove anything, everything I'm saying has already been proven. This isn't Basic Research, it's Applied Science.

 

This is all about mathematics and engineering (with a little materials science and metallurgy). With that in mind I should probably bow out of this discussion, as I won't be able to explain this in a way that makes things clear.

 

I'll try like this...

 

The underlying theory has been very well established. Experiments still take place (to establish mechanical properties) with very well controlled, standardised methodology. If you want to know the theory and the relevant experiments, you'll want to collect a few textbooks in the aforementioned subject areas rather than looking in journals. The contents of those textbooks would be pre-requisite knowledge to really understand the content of the journals of those subjects. To properly understand would require quite a lot of study. With Mechanical Properties (e.g. toughness, strength), Geometrical Properties (e.g. second moment of area) and a grasp of Mechanics, you can understand all of this without the need for destructive testing of swords (as highly controlled destructive testing is already being carried out on geometrically identical samples).

I explained the testing methodology for toughness. Other mechanical properties have similarly rigidly defined standardised testing protocols. The bulk mechanical properties of various alloys (having undergone specific heat treatments) will give you a clear understanding of how swords made of those materials will respond to the same abuse relative to one another (all else being equal), without needing a destructive test each time.

 

The best way to assess the difference made by steel and heat treat is to compare them directly, not to add a number of confounding variables.

 

If you are set on destructive testing of swords, your best option would be to buy a traditionally made shinken and commission an utsushi from Howard, build a testing apparatus and document the results of your destructive tests. Otherwise you'll never get to the bottom of this if you want to use an experimental approach. If you don't do it, I don't imagine anyone else will ever fund this.

 

The problem with a testing methodology which allows other (uncontrolled) variables is that it's easy to optimise for the test (if there is incentive to do so).

 

You remember the emissions scandal?

 

Cheating those kinds of tests is very easy when you have control over enough variables. This is the same way. It's easy to tweak the design of a sword to "cheat" the testing methodology (whatever the methodology is) so long as you know the methodology ahead of time and have freedom with regard to a few variables.

 

This is what happens with the ABS Master Bladesmith tests. The knives they make for the test wouldn't be great in real world use because every aspect is optimised to pass the tests (at the expense of real world practicality).

 

12 hours ago, AntiquarianCat said:

I agree, completely. Which explains the performance variations seen. I am just saying empirically the results we have range from that Clark to the Oni. Could there be above? I'm sure there is but right now I don't think there is enough evidence to say how much and how often with certainty.

 

We have plenty of evidence to know that it's certainly every time Howard's HT is used and the blade doesn't fail during the HT.

 

The causality is very clear and obvious.

 

Regarding Chinese blades (which nobody else has been discussing)...

 

Howard gives his blades an edge at 57-58 HRc (Martensite) and a body around 48-50 HRc (Bainite). It would be easy enough to test the hardness of one of the Chinese swords.

 

Checking the microstructure would be more involved and would require a professional to prep the surface and interpret what they see under the microscope.

 

If edge rolling is common in Chinese production blades, I would suspect that they're Bainite at the edge (as opposed to Howard's Martensite edge) and that the edge is softer.

 

12 hours ago, AntiquarianCat said:

Yes I would. I am quite surprised that a high end maker does not carry out destructive testing. That was very much the norm in the past. Surely there must be more videos or tests out there or else on what evidence do we say anything about performance.

 

Why destroy a $5k blade, what would the incentive be?

 

Would you be inclined to spend a week sweating in a forge to craft something by hand and then destroy it for no good reason?

 

Be sure to share those videos if you find any.

 

12 hours ago, AntiquarianCat said:

How can we know a test with unremarkable results sets a low water mark? For anything? Without any more information it could be the upper bound. It just seems a major assumption to say every sword preforms far better than the one in the video when we acknowledge there is no evidence.

 

Is the whole field of Fracture Mechanics not enough for you?

 

This is kind of like arguing that you have no reason to believe that a car with no wheel bearings or tyres would be more fuel efficient with wheel bearings and tyres (and requiring an academic paper for each individual car to verify this).

 

Think about this:

If you know with certainty and mathematical precision that:

• Adam can bench-press 100kg.
• Brian is 3x stronger than Adam (in every lift).
• Charles is half as strong as Brian (in every lift).

 

How much can Charles bench-press?

 

Do you need to go down to the gym and find out experimentally or is there perhaps a simpler way to arrive at an answer?

[PNSSHOGUN]

This has been done with a sword by Yoshindo Yoshihara. Apart from the main event of a Kabutowari test at the end, they take swords to two age old enemies; a chair leg and motorcycle fuel tank.

 

 

[AntiquarianCat]

I admit my field probably does affect my views. It's not hard to run into something poorly understood which forces you to play with a black box where you adjust variables and look for results and then form ideas based on them. And even though we have made huge progress in defining how living things work, stuff predicted with a model will often fail to pan out in a trial because unaccounted variables. As you noted there is a zoo of variables concerning a blade ranging from the heat treatment to shape. I don't think it unreasonable to say a work a smith made artisanally will have a lot more unaccounted variables than an aircraft you might have designed - which was made by automated manufacturing down to a micron- so while stuff made through engineering might be modeled well with a formula, it doesn't seem unreasonable to think artisan designed stuff no matter how gifted is more a black box than excel box. I'm not saying anything for or against, I'm just saying I don't think there is enough information to say with certainty. I'm sorry about mentioning the production swords without context, they seem like a good demonstration of how variables like heat treatment affect what comes out of the box and that's the only reason they're relevant.

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Why destroy a $5k blade, what would the incentive be?

Well Clark is a smith and it seems to be customary for smiths to do destructive testing. Other smiths that are lauded will often do destructive testing, the modern ones documenting, ergo I expected he would do what the modal lauded smith does since he is one.

Also, business wise it makes little sense to do destructive testing with what is supposed to be your most flawed work and post videos of it all over the net. It could mislead people into thinking that is the level of performance you offer. It's not so much as be inclined to destroy your work as a would you do crash testing with your car you designed and post videos to convince me it's superbly safe? If you can show, even if the test is flawed, business wise it seems worth sacrificing one of your works as impressionable people like me will be swayed. 

 

I don't think we know with certainty or mathematical precision how an artisanal product works, we have a video of it on the net and that might be the only empiric information we have. So it seems reasonable to me that people may differ on this question. 

I am thinking over your compelling points and don't doubt that steel may be capable of what the math says, I just think something made old style with uncountable variables makes trying to predict harder. Systems biology -which I'm told is the wave of the future- is invaluable for predicting and finding but there is still enough uncertainty that what the computer models may not be how the test turns out. I probably won't mention this anymore since I already aired out my opinion.

[ROKUJURO]

19 hours ago, AntiquarianCat said:

..... The quality of the swords Japan admired certainly surprised me in terms of purity. I don’t know how they were able to do it......

Juan,

 

you certainly meant the purity of the steel. This is partly a feature of the TATARA process - in other cultures it is/was the bloomery furnace. The low temperature and the related fact that the iron does not melt leads to the effect that only iron oxide is reduced to metallic iron. Other metal oxides like manganese oxide need a considerably higher temperature for their reduction, so they remain in the slag together with other possible alloy metals. There still remain some impurities in the raw steel like silica and others, but they are reduced by the raffination process (stretching out the billet, cutting and folding it, then fire-welding it again). In the end this leads to a block of homogeneous steel. 

The analysis of TAMAHAGANE I found in the literature (see below) does not tell if this was taken from the processed steel or from raw TAMAHAGANE which can have varying contents of alloy elements like carbon and many others. So we have to consider that TAMAHAGANE is no wonder material but a base steel which can be turned into very fine and homogeneous sword-steel with predictable properties.

 

The finished blade is a very complex workpiece that derives its properties from the fact that it has a composite structure. Most modern mono-steels cannot be brought to the same level of performance concerning a hard and durable edge combined with a resilient and tough body that will not easily bend or break. 

 

A modern steel may have superior properties in one field or another compared with a traditional Japanese blade, but keeping a very sharp edge while withstandig heavy shocks is very demanding.

 

The destructive tests are nonsense in my understanding. A sword blade should be tried under the conditions that it will be exposed to in reality. Cutting solid steel bars or rocks will only show that you are able to destroy eveything that is man-made. 

 

Analysis of TAMAHAGANE.doc

[mas4t0]

7 hours ago, AntiquarianCat said:

I don't think it unreasonable to say a work a smith made artisanally will have a lot more unaccounted variables than an aircraft you might have designed - which was made by automated manufacturing down to a micron- so while stuff made through engineering might be modeled well with a formula, it doesn't seem unreasonable to think artisan designed stuff no matter how gifted is more a black box than excel box. I'm not saying anything for or against, I'm just saying I don't think there is enough information to say with certainty. I'm sorry about mentioning the production swords without context, they seem like a good demonstration of how variables like heat treatment affect what comes out of the box and that's the only reason they're relevant.

 

I can see why you'd think that, but it's not quite the case.

 

As simply as possible; the ideal structure for a piece of steel is complete homogeneity (lamination is a different topic). This is most easily achieved by fully melting the steel in a "ladle".

 

With the steel entirely liquid it can be stirred to ensure an even distribution of all alloying elements (homogenisation) and liquid chemistry techniques can be used to remove Oxygen, degass, add alloying elements, remove inclusions, remove Sulphur, etc.

 

High grade (premium) steels, which are characterised by narrow chemical tolerances and high consistency, are only possible to produce in bulk due to this process.

 

The history of a material (i.e. processing) influences its structure, and thus the material's properties and performance.

 

Forge welding steel is kind of like taking a dozen small ice cubes, melting the water on the surface and sticking them together to form a single big block of ice. You know intuitively of course that the block of ice would be stronger and less prone to separation if it had formed as one large crystal (i.e. if all the liquid water had frozen together into a single large block).

 

The same idea applies to a piece of steel, which should ideally consist of a single crystal. The negative effects of this can be minimised (maybe eliminated), but even when the steel is worked perfectly, the resulting steel would only be equally good (mechanically) to mill steel (of the same chemical composition) and not better than it.

 

Metallic crystals are not perfect. Often there are empty spaces called "vacancies", where an atom is missing. Another common defect in metals are dislocations, which are lines of defective bonding. These and other imperfections, as well as the existence of grains and grain boundaries, determine many of the mechanical properties of metals. When a stress is applied to a metal, dislocations are generated and move, allowing the metal to deform.

 

The numbers given on the data sheet are based on mill steel. Any alternative approach to producing the same alloy (not involving fully liquidating the steel) will produce at best an equivalent piece of steel and often an inferior piece of steel (from a mechanical perspective), for the reasons explained above.

 

It does not matter whether the (pre-forged) mill steel is forged or is shaped by stock removal. It does not matter if the steel is ground by hand on stones, with a grinder or is machined on a CNC machine. It does not matter if the steel is forged by hand, with a power hammer or by any other means. All that matters is whether or not the piece of steel was damaged by the processing.

 

The same science applies in both cases, it's just a case of how close you're getting to the "ideal" and how much skill and labor are required to get there. The atoms neither know nor care whether they are being forged or ground by hand or by machine processes.

 

The precision of a good blacksmith is close to CNC machining and in many cases will exceed it (for certain items). Skilled smiths can do things by hand which cannot be achieved by machine processes. There's no reason to think of them as fundamentally different. Its like expecting the nutritional content of a cucumber to be different if its sliced by a food processor as opposed to a knife.

[PNSSHOGUN]

Further modern Japanese swordsmith testing:

 

 

[mas4t0]

On 7/18/2022 at 7:25 PM, AntiquarianCat said:

Also, business wise it makes little sense to do destructive testing with what is supposed to be your most flawed work and post videos of it all over the net. It could mislead people into thinking that is the level of performance you offer. It's not so much as be inclined to destroy your work as a would you do crash testing with your car you designed and post videos to convince me it's superbly safe? If you can show, even if the test is flawed, business wise it seems worth sacrificing one of your works as impressionable people like me will be swayed. 

 

I don't think we know with certainty or mathematical precision how an artisanal product works, we have a video of it on the net and that might be the only empiric information we have. So it seems reasonable to me that people may differ on this question. 

 

Juan,

 

Please give me your word that you'll never play Three-card Monte. 🤣

 

I fear that we're now approaching the subjects of Media Studies (e.g. Hyperreality) and Media Literacy .

 

If you didn't see something with your own eyes, it's media and should be viewed sceptically. You know this of course, I'm just defining things as I go for clarity .

 

Even if we saw it with our own eyes we can easily be deceived (e.g. magic tricks).

 

In general I wouldn't trust any scientific findings unless they're from a well controlled study, with a large sample size, replication studies, etc and the field on the whole has reached consensus on the correct interpretation of the findings; hence my strong affinity for textbooks (though always the most up to date editions).

 

I'm fortunate to not be a research scientist, so I don't need to stay up to date with journals.

 

To elaborate a little of what was stated previously; when steel is fully melted you can easily remove dissolved and chemically bonded impurities. How far you want to go with this is a matter of how much you want to spend; you can (for instance) remelt the material under a vacuum (or inert gas) to improve alloy qualities (refined microstructure, further purification, etc). There are a couple of commercially available variants of 52100 which are produced this way, but I don't know if any knife makers are using this steel instead of "standard" 52100 (52100 is quite popular among knife makers in the US).

 

Regarding Howard specifically...

 

He's under-promising and over-delivering (which is ideal). He has no need to self-promote as the word of mouth promotion he receives from his customers has and will always give enough work keep him busy.

 

Most of his customers are practitioners, so the performance is tested. Unreasonable expectations and the bad word of mouth that would follow could ruin a smith. 

 

Ordering a blade from Howard really means that you can specify all aspects of the sword based on what would be optimal for you in an iaito; the blade will perform exceptionally well as a shinken without giving any special consideration to how well it'll hold up.

 

If I were using a Nihonto, I'd most likely need to use a blade a few inches shorter or a fair bit heavier to ensure that it wouldn't bend. It also gives me the confidence to let others use it without worry.

 

Bending plastically (i.e. taking a set) in Nihonto is not ideal; it would be much better if it bent elastically (i e. if it returned to its original shape without the need to apply further external force). Plastic deformation is better than breaking, but it's not without adverse consequences. If you take a bank card and bend it back and forth a few times, it'll break. The same idea applies to a sword, you just get more cycles.

[Jacques D.]

On 7/7/2022 at 7:38 PM, Ninja said:

Hello everyone,

I had a discussion with a person who stated that "Nihontos suck as swords", and more specifically:

 

 

Would someone kindly be able to explain to me if there is any truth to these claims? Thank you

From a scientific point of view, physics tells us that when it's thin enough, it cuts and the harder a material is, the longer it cuts. In the world, the sharpest material is obsidian. That said, a well-sharpened sword cuts as well as any other.  I add that the harder a material is the more easily it breaks, it is a question of organization of the atoms. I know it challenges some beliefs but that's the way it is.

[Apercus]

I had not planned to make any comments on this line of discussion. I’ve found that most people come to the discussion like this with preconceived conclusions based on a little knowledge and state those ideas as incontrovertible truth that can’t be challenged. e.g. “Modern mono-steels are always best”, “Japanese smiths used inferior steels”, “nothing can compare to a modern tool steel”, etc. With the rid of being vilified and derided I will offer a small amount of my own observations and then bow out of the discussion.

 

There is no performance testing comparing modern blades with ancient blades so “conclusions” should be stated as speculation. I also hope no one ever tries to do performance testing on a historical piece. I haven’t seen rigorous comparative testing between modern traditional blades and modern non- traditional blades so predicting those outcomes is just speculation. There are many different types of construction techniques employed by different smiths, including heat treatment, steel composition, etc. You would need to look at the product of each smith to evaluate comparatively.
 

A traditionally made blade is a metal to metal composite which likely has structural advantages over a mono- steel. One of these is resistance to crack propagation. I have used X-ray fluorescence to evaluate alloy composition of a tachi made in the early 1200s. I found iron, .7% carbon, and .05% titanium (an ideal concentration for thermomechanical processing). There were no other “impurities to 5 decimal places. I don’t know if it’s even possible to buy modern steel commercially that clean. Certainly 95% of modern tool steel doesn’t come close to that.

 

Simply machining or grinding a modern tool steel to shape is not the equivalent of forging. The microstructure and grain size can be improved with forge work. Thermomechanical processing (forging with he presence of a microalloying element such as titanium) is a process that increases both the hardness and toughness at the same time. 
 

These are just a few considerations I’ve mentioned. I’m sure there are antique blades that could be outperformed by a modern Howard Clark blade but I don’t know if his work would be as sound in application as a blade by Yoshindo Yoshihara. Until there is controlled comparative testing none of us know. We should not represent speculation as fact in  the meantime. 
 

I’ll go crawl back to my corner now.
 

 

[AntiquarianCat]

With all due respect, I wouldn’t wager my money in a game where I lack enough information to win, god knows I don’t have enough of it. I don’t see information as an all or nothing thing, small scale studies (or even uncontrolled accidents findings) can still uncover an effect if the difference is so powerful that you can resolve it with a small number. That’s how we go from happy incidental findings, tentatively replicated with low n and then convince the NIH/Sponsors to help fund a bigger much more credible test. Preliminary data is very useful for convincing and getting better things, even with science. And by the way if the effect is strong enough what you’ve found with small numbers of mice should replicate with huge numbers of mice unless you had serious errors in method. So yes, I would wager on my small n experiments replicating as I repeat them (or god help me if they don’t!).

 

Your points have been very compelling and I will remember them. I still share Apercus‘ view in thinking the best answer is “we don’t know”. I don’t know how much better an expert artisan’s baseline is than the one example he experimented on if it is not the baseline itself, and unless he gave you some engineering calculations or empiric data it could be argued we don’t really know. 
 

In short, I plead ignorance.

[mas4t0]

13 hours ago, Apercus said:

I had not planned to make any comments on this line of discussion. I’ve found that most people come to the discussion like this with preconceived conclusions based on a little knowledge and state those ideas as incontrovertible truth that can’t be challenged. e.g. “Modern mono-steels are always best”, “Japanese smiths used inferior steels”, “nothing can compare to a modern tool steel”, etc. With the rid of being vilified and derided I will offer a small amount of my own observations and then bow out of the discussion.

 

There is no performance testing comparing modern blades with ancient blades so “conclusions” should be stated as speculation. I also hope no one ever tries to do performance testing on a historical piece. I haven’t seen rigorous comparative testing between modern traditional blades and modern non- traditional blades so predicting those outcomes is just speculation. There are many different types of construction techniques employed by different smiths, including heat treatment, steel composition, etc. You would need to look at the product of each smith to evaluate comparatively.
 

A traditionally made blade is a metal to metal composite which likely has structural advantages over a mono- steel. One of these is resistance to crack propagation. I have used X-ray fluorescence to evaluate alloy composition of a tachi made in the early 1200s. I found iron, .7% carbon, and .05% titanium (an ideal concentration for thermomechanical processing). There were no other “impurities to 5 decimal places. I don’t know if it’s even possible to buy modern steel commercially that clean. Certainly 95% of modern tool steel doesn’t come close to that.

 

Simply machining or grinding a modern tool steel to shape is not the equivalent of forging. The microstructure and grain size can be improved with forge work. Thermomechanical processing (forging with he presence of a microalloying element such as titanium) is a process that increases both the hardness and toughness at the same time. 
 

These are just a few considerations I’ve mentioned. I’m sure there are antique blades that could be outperformed by a modern Howard Clark blade but I don’t know if his work would be as sound in application as a blade by Yoshindo Yoshihara. Until there is controlled comparative testing none of us know. We should not represent speculation as fact in  the meantime. 
 

I’ll go crawl back to my corner now.
 

 

 

Thank you Shannon.

 

I'm more than happy to defer to your superior knowledge on any points of disagreement.

 

There has been testing (of sorts) carried out in dojo, if we want to compare swords in their (current) practical application. I think at this point there's plenty of empirical evidence (in the field) of (contemporary) traditional blades bending (much) more readily than mono-steel blades. This has been my experience as a practitioner and I'm sure others can attest to this too. Tameshigiri tends not to do any more harm to the blade than bending it out of shape.

 

I'm surprised the hear that XRF is considered accurate to 5 decimal places. Is that 5 decimal places of a percentage (as in 0.1 ppm)?

 

I should maybe clarify that my meaning above with "perfectly forged" was very loose (which is to say, misleading and incorrect). My meaning was "free of weld flaws" as opposed to "the grain flow is oriented to optimise ductility, toughness, strength and fatigue resistance."

 

I didn't mean to make apples and oranges comparisons between forging and stock removal. What I meant to state is that it doesn't matter whether you remove material via a milling machine or by hand and that it doesn't matter whether you (hot) forge an object by hand, with a power hammer, with a press, etc (all else being equal).

[mas4t0]

On 7/8/2022 at 5:39 PM, Gakusee said:

Hey, Mark - from which textbook / book are these technical diagrams? Very interesting…. Thanks 

 

This isn't the source of the diagrams, but this might be of interest to some. It's the closest thing to a textbook on sword dynamics which I'm aware of.

 

sword_dynamics.pdf

 

It's ~150 pages specifically on the dynamics of hand-held impact weapons.

[mas4t0]