OceanoNox

Nice one! Funny to see I used the same source for images. @Rivkin, I agree with you, and even would add that we are limited by survivor bias. There is little to say that the blades we have are even representative examples for each era. This is even further limited by the impossibility of conducting destructive analysis in many cases. From some recent articles, the use of X-ray diffraction or neutron diffraction gives good information but is clearly limited. A nice section cut and polished to see the microstructure, get the hardness, chemical composition (melting etc.). To me, Prof. Kitada does manage to have al: knowledge of old steel, modern steel, and history (although maybe more as an amateur than dedicated scholar). Control of the grain size is indeed important, first uniformity, and then small grains, those give the best mechanical properties. For Mn, P, and S, it's also why we add Mn to steel even if we don't need it for the final properties of the steel, it's essentially there to capture the sulphur into MnS inclusions. These are actually not detrimental per se, unless they are exceptionally large, at which point they may become the initiation points of cracks. I want to ask you about the long heating of European swords. This sounds like aging, but in carbon steel, that would spheroidize the steel (form large spherical carbides). Unless it's simply some low-temperature tempering, that might indeed recover some martensite, and at least reduce the internal stresses (to be clear, it was done in Japan too, but for some reason, this is almost never described in documents for the layman). Do you have more info on the topic?

I an not sure what is meant precisely with "alloy steel" or "army sword steel", but the hagane and kawagane with high carbon in older nihonto are spring steels, essentially. The main reasons why Japanese swords bend less and when they do, they remain bent are: (1) Blade cross section: the blades are thick enough that they are resistant to bending. This resistance depends mostly on the Young modulus and the size of the cross section (i.e. it doesn't depend on the type of steel); (2) The use of low carbon steel (sometimes close to iron) for the core, that has such low yield stress that it will deform permanently when bent. The hagane and kawagane may not be permanently deformed but the core is, and the sword stays bent. I have had discussions with friends, and we can continue here, but in my view (and from what I have seen so far), there is little difference between the steels used for swords in Japan and Europe. The main differences seem to be the type of non-metallic inclusions, which form because of elements contained in the original iron ore and the walls of the bloomery furnace, and the hardness. Maybe the cleanliness too (sulphur and phosphorus contents), but I need to gather more data and reports. So far in my review of published data, the Japanese swords' edges appear quite harder than European swords in general (regardless of composition, even some crucible steel swords). I see it as a choice to aim for strong cutting edges, at the expense of impact resistance. I am not sure why this choice was made. Many will say that Japanese martial arts with swords teach to deflect and evade rather than block the enemy's blade, but my own school at least does very hard edge to edge blocks (and I was told to consider the sword a consumable, in a fight).

Yes. I know an experimental archaeologist in Japan working on the evolution of tatara, so I might ask him about that. He told me that Japan exported a lot of swords to China, and I think I read that China decreased the price per sword they were willing to pay, so the Japanese side increased the number of swords sent for the next shipment. It does seem weird that Japan would get Chinese material and send it back, since a lot of the iron technology came from China and Korea. I will reread Prof. Omura's paper with more focus.

To add about Prof. Omura's research paper, it is part of a larger research project, funded by JSPS (Japanese Society for the Promotion of Science, the main government agency for basic research funding, relatively competitive and attribution depends on both the application and the applicant's previous research results and achievements). The topic was "The iron that changed Asia " (アジアを変えた鉄). There was a symposium at Kyushu National Museum (https://www.kyuhaku..../event-220128-2.html), and Prof. Omura's own website gives more details (http://ohmura-study.net/410.html).

To add, also steel from the Netherlands (anywhere, really). I did not know that, but it seems the "nihonto = tamahagane" narrative started, according to Prof. Omura, after the sword ban of Meiji. He adds in the conclusion that nihonto were not made with tamahagane during the bakumatsu because it was good steel, but because it's what the smiths could get their hands on. So tamahagane was mainly used for 70 years out of 1000 years of history for nihonto. This is a tough paper to digest (a lot of content, and it challenges my own ideas on the topic), but very interesting.

Thank you Robert! Thank you for the comments too. I'll answer below, but I'll use your comments to upgrade the file. If I can get close to a "definite" version (HA!), I might upload it. I realized later I had forgotten to erase the duplicated Vickers hardness data. About the concentration of P and S, I have no idea where the sands/ore came from for the old swords (or rather if it was in Prof. Kitada's book, I skimmed over it...). About the folding part, it's the section I am not happy with; I wanted to get over it in one slide, and the nuance is difficult to get. I did want to explain that each type of steel was separately worked before being joined into the final block for the sword. And for the carbon content, I was amazed too. From what I understand, they usually look at the fractured areas when they break the initial metal before sorting into high or low carbon steel. It seems the folding tends to give a pretty consistent 0.5~0.6 mass% carbon, so maybe they realized that a certain number of folding cycles worked. I know that the people from older times were likely just as smart as us, but knowing how little technology they had, I am still amazed at what they did.

I thought it might be East 東, as seen here: http://codh.rois.ac....nsho/unicode/U+6771/ The writing style is Seal script, tenshotai 篆書体. The kanji for king 王 can look like this: http://codh.rois.ac....nsho/unicode/U+738B/

I used the data available. I'd like to keep updating this file, so if you have other sources, please let me know. EDIT: I wonder if the smiths themselves measure the temperature or keep doing it by eye and experience.

Thank you Brian!

Nihonto-Steel.pdf Hello all, I have been recently quite miffed at the apparent return of the "Japanese SteEL was Baaaad" cliche on the internet. I've yet to seen anyone back their claim and decided to gather some of the most excellent data that has been published throughout the years. A lot is in Japanese, which means it remains inaccessible to many. At any rate, feel free to take a look at it. I have focused on the metallurgy, i.e. the chemical composition, microstructure, and mechanical properties. Cheers

This page (http://www.kodokei.com/ot_043_1.html) implies that the so-called tokei tsuba was indeed popular, and the design was already not new in 1770. The page goes on to say that it also looks like a sun with its corona. There is no implication that it's a christian theme, simply a clock gear (specifically a Japanese clock gear). The document cited may be this one: https://kokusho.nijl...io/100238317/2?ln=ja, but it's more than 600 pages long of old Japanese... I have seen it written that the sun/sharp gear appearance is a hint to the Jesuit IHS symbol, but I cannot confirm (the symbol itself is certainly juuust old enough that the Jesuit mission in Japan could have introduced it: 1541 for the symbol, 1549 for the mission). To @Jesta, I feel the same way for many tsuba designs, especially the tosho and kachushi. There is a simplicity and rusticity that is extremely appealing to me, but I wonder what was the intent behind those designs. Is there a hidden meaning? Did they simply like the shape? Was it simple because they lacked the technology or know-how to make more elaborate depictions?

It may be pure coincidence, but the reading shoubu is the same for both 菖蒲 (Japanese iris) and 勝負 (victory and defeat, fight). I do remember that there are several items with puns in them (like a natsume with exactly 6 gourds drawn on it, called "mubyoutan" 六瓢箪, with mubyou 無病 also meaning "disease free", as a charm for good health).

Mekugi should be made of strong bamboo, ideally smoked. You can buy some here: https://www.namikawa-ltd.co.jp/product/143 Otherwise, the next best thing is following this: https://ejmas.com/ti...nart_fowler_0502.htm If you use store bought bamboo, use the bamboo near the outer surface, where the fibers are dense.

I read there are theories about the nature and the mundane themes (like everyday items) being about remembering life and beauty, in contrast to the violent episodes of warriors' lives. As it is, unless someone has some written document or journal that states why some design choice was made, we won't know if it's simply esthetics, religious or philosophical belief, or to invoke protection/strength, etc. Perhaps people who have seriously designed tsuba can weigh in, but I do like the look and texture of the halo (amida yasuri) over relatively rough iron, so in my case, it's less about meaning and more about visual effects.

May I introduce these? https://rank-king.jp...4EAAYASAAEgLlC_D_BwE Apparently made specifically for museums and the like.