Apercus

I submitted a tanto for shinsa to the NTHK in Tampa last year and have not gotten around to translating the papers yet. I’m slow at that. The worksheet gave it 80 points. I was just curious if anyone here sees anything on the papers that would account for the 80 points. Shannon H.

I don’t have anything definitive for you. The samples I examined 25 years ago with SEM led me to believe the areas that displayed utsuri matched the profile of banite. (Fine dispersal if smaller crystalline structures). They certainly were formed at a lower temperature than the martensite because of differential heating. I only stated that I was speculating that much of what we identify as utsuri is actually bainite. Yoshindo Yoshihara noted in his book The Craft of the Japanese Sword, that utsuri was formed at a lower temperature than martensite. That temperature corresponds to the temperature that banite forms. I guess someone will need to make samples and do some research to definitively prove the point. I’m not in a position to do any of that now. Howard Clark claims his blades have a hardened edge of banite which is almost as hard as martensite but which does not have the brittleness of martensite. Bainite is known to have greater toughness than martensite. Perhaps he might be coaxed to share some of his work. Shannon Hogg

Cyril Stanly Smith who was one of the pioneers in metallurgical examination of steels cut Japanese blade sections to reveal different type constructions. One type examined was a san-mai blade but the outer layers were of a medium carbon content rather than iron. With at least 45 points of carbon (I.e. 0.45%) a hamon would be produced. It has been my experience that banite forms more readily in a medium carbon content steel with a differential application of heat. I believe banite is what we usually recognize as utsuri. It’s a shame there hasn’t been more study in this area. All we can do is speculate over the little bit of data available. Just my two cents worth of speculation. Shannon Hogg

I submitted an unsigned tanto in Tampa that received 80 points, I guess I should try and translate the text. Shannon Hogg

That would be nice but I suspect there would be a huge amount of variance just within the different schools of any given time period. You would need a data base of readings from blades of known documented smiths across Japan and through out time periods to even begin using x Ray florescence to determine origins. Shannon H

Many companies that deal with large scale steel sales or reclaim use portable c Ray florescence equipment to sort materials. The equipment runs about $50 K so there needs to be a justification for the cost. Twenty years or so ago I worked at a company that had the equipment and allowed me to use it on projects. That’s what I used to analyze the Ichimonji. I have the results in a box somewhere but the most significant finding was the lack of impurities. IThere was carbon in the range of .5% to 1% depending on location on the blade and .05% by weight of titanium. There was trace amounts of silicone and absolutely nothing else in the steel that could be detected to five decimal places. Titanium is one of three alloying materials that produces a very small grain structure with thermomechanical processing. That increases both toughness and hardness. The concentration of .05% by weight is considered ideal for this. My current job involves thermomechanical processing as an essential factor in increasing mechanical characteristics of jet engine components. I know something about it. As a side note, I have gone to a large salvage yard and asked if they could use their equipment to analyze a blade for alloy content. All they need is a small spot of clean metal and about two minutes. Every time I’ve asked they were happy to help. I would be careful with fresh polish. If you were careless you could get a light scratch. Shannon H

Sorry, forgot to sign again Shannon

I did an alloy analysis of the 13th century Ichimonji tachi I have using x Ray florescence (non destructive). The test showed iron, carbon, .05% titanium, and trace amounts of silicon. The titanium was an ideal concentration for promoting thermo mechanical processing and the silicon would have increased toughness. There were no impurities detectable to five decimal places. Almost no modern steel is that pure.

Thanks for the comments. That’s not my first bad idea. Shannon

I believe there are several effects that are called utsuri and more than one factor that influences it’s appearance. Much of what is termed utsuri is probably banite which forms at a lower temperature than martensite. It appears that a differential application of heat was applied to facilitate the formation of utsuri (banite). The edge was heated more than the rest of the blade perhaps by heating a block of steel and then holding the edge to the lock. That’s how I have made it. I don’t see utsuri if I heat the entire blade to temperature then use the clay coating on the back portions of the blade to allow for differential cooling. That was the more common method of heat treatment during the late koto period and afterwards. I also tend to see more utsuri if the exterior steel is more of a medium carbon content (40 or 50 points of carbon) and low alloy content. These ideas just reflect my limited experiments. I’m sure there are other valid ideas and methods that produce similar effects. Don’t look at this as anything definitive. Just some old random thoughts and memories. Shannon Hogg

This weekend is the Japanese Festival in Atlanta. If a show was held during this same weekend or in conjunction with the Japanese festival the attendance would be far greater than average. Just a thought. Shannon Hogg

Sorry. Forgot to sign again. Shannon Hogg

I am curious to know if anyone has looked at the option of holding a sword show in conjunction with a large event such as the Japanese Festival in Atlanta this weekend. If it was part of the Japanese Festival there would be an issue with large numbers of inexperienced people (and kids) to contend with. In that case precautions would need to be taken for those with tables. Perhaps it could be separate yet connected or not allow young children. Just a thought. It would increase the number of people attending a show and might start more interest in the next generation of collectors. Anyone look at this before?

Tamahagane is produced without melting the iron to a liquid and carbon is introduced through carburization of the iron sand in the atmosphere of the tatara to produce steel. Nickel rich iron ore sands can be used to produce a steel that will harden with heat treatment even with relatively early primitive technology. There are specialists in archeotechnology who have made legitimate suggestions that not all ancient blades were made from meteorite iron. We could perhaps find out if the archeologists were ok with having their precious artifacts cut up and tested. I’m open to the possibility of some of the dates being pushed back a bit. Perhaps time will tell.

I’ve thought about this difference between the appearance of choji on each side of the blade and proposed a possible explanation years ago. I believe the early application of choji in some schools was created by a different process than latter attempts. Instead of using clay and a differential quench a blade can be heat treated by a differential application of heat. I have heated a long block of steel/iron to a bright yellow heat and used it to introduce heat to the edge of a blade. I quench the blade when about 1/3 of the blade width is past the transformation temperature. This also tends to produce utsuri if the exterior steel has a medium to lower carbon content. Utsuri, which I believe is banite, forms at a lower temperature than martensite. If the blade has had deliberate hammer marks left on the surface (think small round ball peen hammer marks) then a choji hamon may appear after heat treatment and polish. The martensite will form at differing depths because of the depth of indentations. There is also the influence of how and where the vapor barrier appears in a water quench. There are ways to enhance this effect which would require too much space here to describe. When you hammer indentations on one side of a blade and then flip the blade over to hammer indentations on the other side some of the profile of the first side is removed and the appearance of choji will lessen on that side. I’ve done this at a forge and seen the results I have described. I’m sure the smith would be aware of the effect and I would expect the best choji to appear on the side with the signature. Sorry for the long post. This was just the results of my own speculation and experiments a long time ago ShannonHogg

I don’t have the background for this so it’s just what appeals to me . I like the steel in #3 best. I like the hamon and steel in #5

I’m already mentioned mine, the juyo Ichimonji from the kamakura period. It was the second Japanese sword I had ever seen and I bought it sight unseen for a $10 trade. I didn’t know anything about swords but I was overwhelmed with the metallurgy I saw. I’m glad I didn’t cut it up to examine samples at the time.

Thanks. That helps. I don’t have the references yet but I will be purchasing them soon.

https://imgur.com/40UhWiM https://imgur.com/wXUglWk https://imgur.com/AYCXvdu https://imgur.com/lyDxHNf https://imgur.com/mKiMkjR https://imgur.com/m7PYVwd https://imgur.com/hyDRxBw https://imgur.com/MXSZq4v https://imgur.com/KLAQLVp https://imgur.com/uKnRdWd https://imgur.com/lDeAay8 https://imgur.com/uQoeliN I've attached links to a katana I'm trying to find more information on. If I have translated it correctly, it's signed "Mino ju Shige Hiro". There may be a date on the opposite side but it's not distinct enough to read (if it's actually there). I have not seen a signature with the Hiro written this way. I'm trying to identify a time period and verify my translation. My best guess so far is Edo period. The nagasa is 26.25 inches. The steel is dark and the file marks on the nakago are take no ha. At some point it looks like the nakago was struck by a bullet or shrapnel and poorly straightened. One of the last owners began to "clean" the nakago unfortunately. The blade is solid and I like it. It's probably not worth having it polished but I think I might have it done anyway. It's one I think I will keep and it would look good in polish so it's worth it to me. I don't have access to a lot of books and I'm not that familiar with Mino swords. Any help would be appreciated. Shannon Hogg

Interesting. Everything you say about historical blades sounds right. There may be multiple and differing things we call utsuri or multiple ways to produce it. I only did a limited amount of experimentation and I no longer have access to X-ray diffraction and an electron microscope or the energy to work long hours at the forge. I can only say the method I use to reliably produce banite/utsuri is by heating only the edge of the blade past the transition temperature and by alloy selection. Yoshida Yoshihara describes this very process in “The Craft of the Japanese Sword”. There’s not a lot else written about it that I can find other than some technical journals about banite formation. Maybe someone will experiment a little and publish results. Shannon Hogg

Sorry, I forgot to sign again. Shannon Hogg

Back when I was examining the metallurgy of Nihonto I came to the conclusion that most utsuri was a microstructure called banite which is almost as hard as the martensite at the edge but much tougher. It would give the blade improved strength and hardness. Banite forms at a slightly lower temperature than martensite which means the blade was not uniformly heated to the same temperature. I found it was more plentiful on medium carbon content steel but I can’t say that is true for all alloys. I believe many of the older koto blades were San mai with medium carbon content in the outside layers. It’s just my speculation but perhaps that’s why utsuri is more common in some schools and periods. All of that is just my two cents worth from a little bit of experimentation a long time ago. I’m sure there are more knowledgeable people here.

I had the tachi with me at the Florida show but didn’t really get to show it around. I’ll post more photos when I get time to experiment with lighting and another camera. Perhaps this weekend. I still stay too busy with work. Shannon Hogg

https://imgur.com/aqEIc8X Maybe I have it right this time Shannon Hogg

First image was incorrect. Try this one. https://imgur.com/aqE1c8X Shannon Hogg