How effective would a sword be without a hamon?

[piryohae3]

What are the practical benefits of the more complex lamination types?

[SAS]

I beleive they were looking for durability and impact resistance while still maintaining a sharp cutting edge; by having multiple layers of differing carbon content and hardness, they could try to achieve a higher survival rate of the sword in battle. They were using an approach based on practical results without understanding the metallugical science behind  the phenomena.

[mas4t0]

Lamination creates a composite material. Composites allow you to combine materials, to make the most of each respective material, rather than accepting a compromise between the two. With more complex lamination, you have more fine grained control over the resulting properties and they are combined more effectively. I think that in the case of Nihonto, the major benefit is slowing crack propagation, as mentored earlier, resulting in bent blades rather than broken ones.

 

The hard steel has the highest resistance to bending and the best edge holding, but is most prone to cracking, and once a crack is formed it'll propagate all the way through the layer quite quickly. When the crack reaches a softer layer, the crack will not propagate as readily through that layer, so the sooner you reach a lower carbon layer, the sooner the crack is halted.

 

The issue though is that without a decent amount of high carbon steel to provide strength, the blade will bend much more easily. Additional layers allow both of these factors to my more fully allowed for.

 

This is difficult to put down succinctly, material properties alone make up a whole course of an engineering degree and any of the textbooks on composite engineering run ~500 pages, so a full explanation is beyond the scope of a few forum posts.

 

To illustrate the point, consider modern composites:

 

A. Carbon fibre composite

 

Carbon fibres have an exceptional tensile strength to weigh ratio, but no compressive strength. As fibres, they buckle under compression. As such, they need to be combined with a resin to bind them together, give them structure and provide compressive strength.

 

B. Steel reinforced concrete

 

This is much the same mechanically. Concrete is strong in compression, but weak in tension, while steel is the inverse. In each of these cases, the ratio of the two materials and the way in which they are combined is of the utmost importance.

 

Also consider an oil painting. The paint will crack over time, but the cracks do not propagate through the canvas.

[piryohae3]

I wonder how swords of other cultures fare in battle VS Japanese swords in terms of durability.

[mas4t0]

I wonder how swords of other cultures fare in battle VS Japanese swords in terms of durability.

More durable, less sharp, poorer edge retention.

 

This is well documented by historical sources.

 

The British marveled at how the Japanese blades retained their edge, while their own sword needed 'sharpening' (though more likely honing) daily in order to cut well. A lot of this is likely down to metal scabbards, but the accounts speak for themselves.

 

The same is true today for kitchen knives. European style knives (Wusthof, Henckels, etc) are considered by many enthusiasts to be 'beaters'. They'll take a lot of abuse, but they won't take or hold a great edge. Traditional Japanese knives are the opposite. While a Western knife blunts by edge deformation, a Japanese knife losses sharpness by micro chipping. I use these as comparison as both are rooted in their local sword making tradition.

 

The difference is related to the hardness and thickness of the edge. For a given steel, it can usually be assumed that with 'good' heat treatment, hardness and durability are inversely correlated. This in a nutshell is what takes place during tempering, where hardness is reduced in exchange for toughness. The same is true for tempered glass, it's softer so scratches more easily, but is much more durable and less brittle than untempered glass (look up Duralex if you're interested).

 

 

Edit: Graphs added for clarity. You'll see how HARDNESS and STRENGTH correlate, while TOUGHNESS is inversely correlated, so it is always a compromise between them. All of these material qualities are important in a sword and lamination allows you to make separate optimisations for the cutting edge and the body of the blade.

 

Hardness and Toughness Vs Tempering Temperature

 

 

Strength vs Tempering Temperature

 

[Dave R]

 A short extract from a 19th C book, dating from the Crimean War period. A Royal Navy expedition chasing up Russian ships and installations based itself for a while off the coast of Japan. 

 

 

[mas4t0]

 A short extract from a 19th C book, dating from the Crimean War period. A Royal Navy expedition chasing up Russian ships and installations based itself for a while off the coast of Japan. 

 

Thanks Dave. It's always good to see it in primary sources from the men who experienced these things first hand.

[Peter Bleed]

 Some of us are interested in more than what a sword would sell for. (No offence).

Forgive me for suggesting that DEALING in swords was a part of the the appreciation of Nippon-to. I offered this a a quip, but there is a larger point. Indeed, Japanese swords were excellent weapons. Young men trusted their lives to them. And in that situation the sword users wanted some evidence that these weapons would not let them down. To make trustworthy weapons Japanese smiths developed highly routine methods of making steel and heat treating it effectively. Those methods gave their sword visible characteristics that warriors could observe and that smiths could replicate.  Japanese culture likes routine - and warriors like trustworthy weapons. Hada was a reflection of systematic production of carbon enriched iron. Hamon was a reflection of refined, systematic and controlled edge hardening. If you could SEE this stuff, you could determine that you were getting a "good" sword.es that produced Hada/Hamon are NOT unique to Japan, but they were practiced in highly routine ways in Japan. Smiths all over the pre-modern world developed means of adding a bit of carbon to iron and making the result tough enough to stand up to battle. What is UNIQUE(?) to Japan is the production of routine characteristics that let swords be objectively evaluated - visually. A sword without a HAMON might be OK, but if you are laying your life on the line, Japanese warriors wanted to see evidence of quality. A nice clear hamon could be taken as evidence that the blade was well made...

Peter

[piryohae3]

I suppose Japanese swords having a harder, sharper edge suited their needs just fine since they weren't clashing on things like chain mail or plate armor.

[mas4t0]

I suppose Japanese swords having a harder, sharper edge suited their needs just fine since they weren't clashing on things like chain mail or plate armor.

At the time of the account provided by Dave, the days of full plate armour were long in the past. At most someone may be wearing a breastplate, but I don't think these were standard issue for the British.

 

That is to say, clashing against plate armour was likely not a primary concern influencing the design of British swords at that time.

[mas4t0]

Forgive me for suggesting that DEALING in swords was a part of the the appreciation of Nippon-to. I offered this a a quip, but there is a larger point. Indeed, Japanese swords were excellent weapons. Young men trusted their lives to them. And in that situation the sword users wanted some evidence that these weapons would not let them down. To make trustworthy weapons Japanese smiths developed highly routine methods of making steel and heat treating it effectively. Those methods gave their sword visible characteristics that warriors could observe and that smiths could replicate. Japanese culture likes routine - and warriors like trustworthy weapons. Hada was a reflection of systematic production of carbon enriched iron. Hamon was a reflection of refined, systematic and controlled edge hardening. If you could SEE this stuff, you could determine that you were getting a "good" sword.es that produced Hada/Hamon are NOT unique to Japan, but they were practiced in highly routine ways in Japan. Smiths all over the pre-modern world developed means of adding a bit of carbon to iron and making the result tough enough to stand up to battle. What is UNIQUE(?) to Japan is the production of routine characteristics that let swords be objectively evaluated - visually. A sword without a HAMON might be OK, but if you are laying your life on the line, Japanese warriors wanted to see evidence of quality. A nice clear hamon could be taken as evidence that the blade was well made...

Peter

Do any primary sources detail objective criteria (beyond checking for flaws) by which blades for average bushi were visually assessed in the past?

[Dave R]

 Relevant article from one of my favourite sites.

 

 http://www.ksky.ne.jp/~sumie99/flaws.html

 

I was reminded of this by Ken's post in another thread.

[ROKUJURO]

.....What is UNIQUE(?) to Japan is the production of routine characteristics that let swords be objectively evaluated - visually. A sword without a HAMON might be OK, but if you are laying your life on the line, Japanese warriors wanted to see evidence of quality. A nice clear hamon could be taken as evidence that the blade was well made...

...

Peter,

 

I have read that swords having been produced for battle - especially in KOTO times - were sharp, but not 'art polished' as we know it today. It seems that the very fine polishes that show all details we can enjoy today came only up in the late EDO JIDAI.

[Dave R]

At the time of the account provided by Dave, the days of full plate armour were long in the past. At most someone may be wearing a breastplate, but I don't think these were standard issue for the British.

 

That is to say, clashing against plate armour was likely not a primary concern influencing the design of British swords at that time.

 

 Both British troops and Samurai still had a good chance of running into an armour clad opponent at this time. Both Indian and Japanese warriors  were still wearing mail and small plate armour on occasion , though not full plate.

    Different methods were used to deal with the problem. British troops in India would use the point, which readily goes through mail. Samurai carried a very hard edged two handed sword and cut through mail and thin plate....

 

Getting back to the original question though, in my opinion blades made with a full temper without a hamon  are perfectly effective, a hardened edge can be present with no hamon visible, but lack of hamon is a flaw in Japanese blades.

[mas4t0]

Different methods were used to deal with the problem. British troops in India would use the point, which readily goes through mail. Samurai carried a very hard edged two handed sword and cut through mail and thin plate....

 

I've not heard before that the mail and plates of Japanese armour could be cut with the blade edge. If that's the case, wouldn't it make the armour somewhat redundant?

[DoTanuki yokai]

http://www.shinkendo.com/new/shinkendokabutowari.htm

 

Some examples of japanes swords cutting through armor.

[Dave R]

I've not heard before that the mail and plates of Japanese armour could be cut with the blade edge. If that's the case, wouldn't it make the armour somewhat redundant?

 

 Any armour can be pierced, penetrated or destroyed, ask anyone who mans a Tank! The point of armour (even today) is that it protects against shrapnel, glancing blows, expended projectiles and uncommitted attacks,... not that it makes you invulnerable!

 

As soon as guns appear on the scene armour becomes less of a protection, but.... in an encounter or street fight it gives an advantage. This is why the heavy armour of the 16th century became obsolete and more for parades than the battlefield. Think of these  kusari  as being in the way of a threat level one or two  "second chance body armour" rather than an Osprey.

[Dave R]

This guy Kataoka Dengoemon Takafusa   is wearing a quilted armour of small plates sewn between layers of cloth, and Ushioda Masanojo Takanori  who looks like he is wearing fishnet, is wearing that uniquely Japanese open style of mail. 

 

 It's light armour, and would not stop a full on two handed cut from a trained warrior, but that is what it would take to get through it. A big advantage in a melee.

[SAS]

I was at Bob Benson's house some years ago when he showed me a Japanese plate armor that had a depression in it from a musket ball....pretty cool, and i will bet the dude was happy he had it. Plate armor seems to have become more popular with the introduction of firearms to Japan.

[ROKUJURO]

To be clear, san-mai blades do not show a hamon.....

....which is why I set "HAMON" in quotation marks.

[mas4t0]

....which is why I set "HAMON" in quotation marks.

It wasn't meant as a correction, just a clarification.

[mas4t0]

Are there any reliable details known about the range of carbon content for the finished shigane, kawagane and hagane respectively?

 

Do we know any specifics on the target tempering temperature for Nihonto (or any info on the amount variation) or any range for the hardness of traditional blades after heat treat?

 

I remember reading that testing had found 61 HRC at the edge on an untempered Nihonto immediately out of the quench, and I think 45 HRC on the edge of a tempered Nihonto. I don't know how worthwhile these numbers are as it's a tiny sample size.

 

I've also seen a metallurgical analysis, but again, as I recall, it was only for a single blade.

[ROKUJURO]

Mark,

45 HRC on the edge of a finished sword blade would not be enough. A very cheap modern kitchen knife is expected to have around 50 HRC.

As far as I know, carbon contents of the different steel components vary quite a bit, but are usually within reasonable and useful dimensions. That is about 0.7 to 0.8 in the YAKIBA, ca. 0.3-0.4 in the SHINGANE.   

Quenching and tempering of Japanese sword blades (YAKIIRE and YAKIMODOSHI) follow the requirements of low alloy carbon steel as in the rest of the world, e.g. quenching at about 800°C, annealing at about 200°C. These temperatures are not technically controlled but estimated by the experienced smith, following the colours. 

From time to time I find research results about this subject. See attachments

mechanical-properties-of-samurai-swords-carbon-steel-made-using-atraditional-steelmaking-technology-tatara-2169-0022-1000162.pdf

Material and manufacturing of blade steel (1).doc

[mas4t0]

Thanks Jean.

 

I was surprised by the 45HRC result, but hadn't seen any other results from practical testing.

 

The first study offers 0.55% C, 0.40% C and 0.20% C respectively. So if we take the cutting edge as being somewhere between 0.55-0.8% C, that should make it quite similar to 1050, 1075 or 1086, which all make good monosteel swords for practical use.

 

The claimed 6 GPa would put the edge at 57HRC, while the HV 866 mentioned elsewhere would put it at 63HRC.

 

I see that they state 770-850 celcius for the quench, but I don't see any mention of tempering, am I missing something or did they not temper the quenched sword?

 

It seems reasonable that the 63HRC would be from the quench and the temper drops it to 57HRC, but I see no mention of tempering.

 

Thanks again.

[ROKUJURO]

Mark,

until quite recently, YAKIMODOSHI was rarely mentioned in the literature.

As far as I know, most swordsmiths will perform the annealing right after the quenching which is technically very reasonable. While we in Western countries use annealing furnaces with computer controlled temperature or a separate gas flame (that is how I do it), the Japanese swordsmith does this in his forge. Temperature control - I have difficulties calling that so - is done by watching water drops falling on the blade. A 'seasoned' smith knows from experience how fast these have to evaporate to guess the actual temperature. 

This is much more difficult than the YAKIIRE where the radiant heat colour gives you a good indication to the temperature.

[mas4t0]

Thank you Jean.

[SAS]

Absolute hardness is not the only thing to consider; usage is very important as well....a kitchen knife can be harder, as it is used in a different manner than a sword, which is swung vigorously at a target, and could shatter if too hard and not resilient enough.

[mas4t0]

I was thinking about the edge failure method.

 

I have a mizu honyaki (differential heat treated with water quench) kitchen knife made from shirogami #2 steel; which is a very pure low alloy steel, but with 1.3% C.

 

It's claimed these are left in the range of 65HRC even after tempering, it's very brittle. It takes an extremely acute edge and holds it very well, it'll fall straight down though soft tomatoes under its own weight, but a touch on a cow bone could cause a chip. Horses for courses.

 

I have some other knives which are claimed to be in the low 60s, and they are more durable but still lose sharpness by chipping chipping rather then rolling.

 

On the other end, German knives are often ~58 HRC and generally experience edge failure by deformation (rolling) rather than chipping.

 

It seems like edge failure methods for kitchen knives transition from rolling to chipping at around 60 HRC though these are different steels so it's only a rough estimate and could be a few points off.

 

Of course the edge geometry and usage cases are very different, but I would presume that this pattern would hold on other blades as it's a matter of the material properties of the steel.

 

The Japanese didn't hone their edges between sharpenings as far as I'm aware, while the British at times did so daily (as is best practice with European kitchen knives too).

 

What are your thoughts Steve?

[SAS]

The processes of sharpening and polishing swords are essentially the same, and it was done whenever necessary. I have read some anecdotes about samurai plunging their swords into sand before battle to round the edge to make it less susceptible to breakage when striking armor, whereas a sharper edge would be better against fabric and flesh during more normal times. As noted previously, the IJA had a manual dealing with edge treatments, along with a maintenance kit, in WW2.

[ROKUJURO]

.....On the other end, German knives are often ~58 HRC and generally experience edge failure by deformation (rolling) rather than chipping.....

 

You have to go back in history to explain this.

 

Early European knives (starting with Celtic times 800 B.C. up to the pre-industrial period mid to end 1800) for the broader public have often been made by blacksmiths with no special experience and knowledge about steel metallurgy. They used the material that was available to them, and often their steel was of inferior quality compared to the material that was used by specialized blade and sword smiths. Heat treatment was basically known but was partly obscured by mythology and was not a well researched science as it is today. These 'normal' household and workshop knives (and this includes all cutting tools for crafts) had to been sharpened on a daily basis, depending of course on the use. This led to knife constructions with very thick blades to ensure a long life. The HOLTMANN dissertation (a technical survey on about 1.300 early medieval knives) showed that the back (MUNE) of most average household knives had about 8 mm thickness! 

 

In the same period, sword and specialized knife smiths had better refined material and more sophisticated methods of forging and heat treatment, leading to better quality and performance. Their forges were often related to wealthy noblemen who supported them financially.

 

Stefan Mäder has done his famous research on early medieval Alamannic sword blades ( http://www.schwertbruecken.de/english/starte.htm). He was able to show how close European smiths were some five centuries earlier to the basic Japanese forging techniques.

 

The heat treatment of steel was known in principle, but it was kept secret by smiths. In pre-industrial times in Europe, this was mostly a thing of trial and error, and as a poor foot soldier (or ASHIGARU) you could find yourself on a battlefield with a simple (and cheaper) sword that was likely to bend or to break. I think this situation was not much different in Japan and Europe. 

When we are talking here about Japanese sword making methods, we often leave out background knowledge that is essential to understanding what is going on in the steel. Let me cite a phrase from Mark H. (post #33): 

 

...Lamination creates a composite material. Composites allow you to combine materials, to make the most of each respective material, rather than accepting a compromise between the two.... 

 

What does that mean? What is lamination? 

 

Just to explain this a bit to those interested, lamination does not mean the production of one of the steel components of a blade by repeated folding and fire-welding. In this process, we have as a result very thin layers of steel with homogenous carbon distribution, bonded very firmly. The thinner the steel layers and the higher the temperature, the faster the carbon migration will be.

This material is very close to modern mono-steel. The carbon level in this material can be controlled by the number of folds (and welds) and by the time and temperature to which the steel is exposed to heat. 

 

Lamination (in the context with traditional cutting tool forging) means the combination of steels with different carbon content to a physical unit. Carbon distribution between these steel alloy layers is not intended, and only then the desired performance is achieved.

 

Less experienced smiths who work too slowly (who have no helpers), too hot, or who do not work according to the requirements of the material, will not achieve the optimuml performance of the sword.

 

This is just a small part of the craft background (not even metallurgy), and in olden times, the 'battle test' was the proof for good (or bad) quality of a blade. In times of no life insurance, you would have to trust the abilities of your swordsmith!