Kiridashis and credit cards

Mecha

Titanium Bladesmith
Joined
Dec 27, 2013
Messages
9,179
While working on some bigger blade projects that take a lot of time, I've been making some little kiridashis and credit card knives for those who'd like a little piece of titanium goodness but who don't need a sword.*

The kiridashi is a great little all-purpose utility blade that does well in hardened ti alloy, and the credit card is a nice backup or emergency blade that uses your wallet as a sheath, so it can ride along with you all the time!

These little credit card knives are made of a new-old titanium alloy, Ti 8mn. Alloyed with only 8% of manganese, this is the strangest titanium alloy I've yet to encounter. It appears to make a really good blade, although the heat treatment has been elusive and difficult to pin down. This alloy gets very hard and very sharp.

Ti 8mn was formulated in the 1960s in the USA as part of the development of nuclear submarines. The company that made it, Reactive Metals, was absorbed by a different company in 1982. The last of the 8mn was probably made in the 1970s. I was fortunate to get ahold of a small sheaf of this alloy in very thin stock, as well as three small pieces, slightly thicker, that appear to be from some of the original Ti 8mn from the '60s. The alloy is at least 50 years old.

Since it's nice and thin, making credit card knives with some of the alloy is helping me to zero in on the proper heat-treatment for using this alloy as a blade, so that swords and knives to come will be optimized. Swords and knives made from this alloy will mostly be san-mai construction, with layered Ti 8mn as the core.

A face only a mother could love: the colors and slick, lubricated feel of this alloy is unique.

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The simple kiridashis are made from Russian ti alloy BT23, which over time has proven to be the best overall blade alloy I've found so far, especially for big blades like machetes and swords. The reason it beats the Ti Nb isn't necessarily because it is a better as blade, so much as it's easier and more consistent to heat-treat, deeper-hardening, and in some other ways is easier to deal with when making a long blade. In the end, if done right both make a really great long blade, with a few pluses and eccentricities for each.

The idea of these was to make an "EDC kiridashi" that one can carry as a tiny fixed blade, in a side-pull belt sheath. The sheaths are lined bison hide, and the package is smaller than it looks, barely wider than a typical belt.

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I'll be making a few more rounds of kreditnaya kartitchka knives, and a few more kiridashis, and will try to get some listed on Bladeforums to be available for forumites!



*I'd like to take this moment to address this idea of "not needing" a sword. You do need a sword, you just didn't know you needed it until you have one. o_O Practicing cutting and forms with a good sword is a fantastic way to get into the moment all zen-like, it is great for your health and concentration. And you will need to concentrate or it may not end up being good for your health. If you're into blades and don't have a decent thin, well-balanced sword in a style you like, then you should consider getting one. o_O
 

sloth357

Platinum m0f0
Platinum Member
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slippery. what kind of interest rates do those cards come with? (I need persian slicey stabby sharp thing)
 

Mecha

Titanium Bladesmith
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Dec 27, 2013
Messages
9,179
The oldest of the 8mn ti, of which I have but a couple of tiny sheets, has layers within it. This isn't galling; the belt was new and sharp, cutting cleanly. Could look amazing on a full-size blade.

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Mecha

Titanium Bladesmith
Joined
Dec 27, 2013
Messages
9,179
Mecha Mecha this story is for you - they use Ti185, but the concept of higher heat, then lower to produce really strong Ti is interesting
not sure if you've ever come across this one

https://www.pnnl.gov/news-media/pnnl-unlocks-secret-worlds-strongest-titanium-alloy


I've seen that one. Like with most new titanium "research," they are just doing the same thing over and over again and acting like it's new. I run across this phenomenon regularly. It's like having people do big research into heating up steel, quenching it, and tempering it, and then acting like tempered martensite is a new discovery. None of these university ti researchers ever seem to do anything different, other than fussing with the alloy content. You offer up a research grant, it gets used - all they did was HT titanium alloy in the industry standard fashion that's been used for 50+ years.

I doubt titanium will never get extensively used in vehicles (except possibly in a niche Lamborghini-type way), because of multiple reasons. Costs of ti, costs of manufacturing, inability to weld it to steel, dangers in manufacturing, etc. There's also the prospect of having a car doing 80 down the highway and getting into a wreck, throwing massive magnesium-fire temperature sparks as it skids down the road, and exploding.

I can't remember the terms at the moment, but in metallurgy there are two main ways to mess with the properties of the base metal: through altering alloy content, and through heat-treatment. Titanium is considered the former type; it is altered though alloy content rather than heat treatment, which generally remains almost the same no matter the ti alloy. Even my weird heat treatment is heavily dependent upon alloy element content to get a good result, and most ti alloys don't cut the mustard.

I will admit that Ti185 is probably very strong and more easy to form than many other ti alloys, and also a lot easier to heat treat to high "strength."
 

Mecha

Titanium Bladesmith
Joined
Dec 27, 2013
Messages
9,179
To add to the above, I believe that particular article spawned from testing to see if that ti alloy could be used in cars because it could possibly yield a vehicle with better MPG, sort of like Ford with their aluminum-body F-150. If the ti was strong enough, it could be not only lighter by volume, but thinner than the steel used.

A titanium car would be awesome, but there are too many other factors that get in the way. So in this case, research money was spent on exploring the alloy for that use, and what ended up happening was the alloy was heat-treated in a standard way, and shown to have increased strength due to HT which is totally normal for ti that's heavy in beta alloying elements like Ti185.

For my purposes, I aim to increase hardness to decent blade levels, reduce galling to zero, keep the grain very refined, and preserve flexibility and shock strength (avoid brittleness, it's easy to make ti brittle), to produce a very thin edge that is stable even under heavy, hard impact... a sword blade.
 

WValtakis

Engraving, Ti anodizing, regrinds and mods
Knifemaker / Craftsman / Service Provider
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I guess my 'dashi got lost in the mail:(:p;)
 
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