Titanium as a blade material?

J

JustSomeGuy

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Mar 12, 2009
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I'm sure it has been asked before, but apparently my search-fu is weak today. My wife recently bought a rotary cutter that uses titanium blades, which got me wondering why it doesn't get used for blade materials in knives. I know there are many alloys of titanium, wouldn't at least one of them be suitable for blades? Also, would you expect her to get the 2-3 times blade life out of them as the manufacturers claim?
 
Most titanium alloys are too soft to be able to hold a proper edge long enough to make its use for blades logical. In some cases where corrosion resistance is valued more than edge retention like that of dive knives it is used. You can also get knives like what warren thomas makes where the edge of the titanium blade is carbidized and holds an edge relatively good for the type of material it is. Titanium has a better strength to weight ratio than steel so it makes a good alternative to it when you think of a handle material if weight is an issue. Titanium has great properties for certain applications but as of yet their simply isnt an alloy yet that would make it really worth using over the many variations of steel.
 
Titanium sure is used as a blade material, just not in the kind of quantity, and usually not for the same uses as standard steel blades. As the rotary cutter goes, i bet the blades are titanium nitride coated (for rust resistance) or something, and they just call them titanium blades. As for why you don't see Ti used as a blade material, it's mostly because of how soft it is. in the mid to high 40s on the rockwell scale i think. There are surface treatments that can raise the hardness of the titanium (carbidizing) but these add thickness, and don't produce a real razor edge. The real advantage to titanium is weight and corrosion resistance, which does make them a semi-popular option with scuba divers. I happen to have a pry-knife made of titanium. It's got a carbidized cutting edge, but it's not all that sharp.

There is one alloy of titanium that is used in blades, and it's called SM100, it's a proprietary blend of nickel titanium (not to be confused with beta-ti) that gives all the benefits of titanium (light weight, completely corrosion-proof) with a lot of the benefits of a traditional steel (ie: it can be hardened to regular blade hardnesses). The reason you don't see SM100 all over the place is really three reasons:
1.) it's fairly new as alloys go
2.) it is produced in small batches, it seems
3.) it is prohibitively expensive to use in a lot of applications. (probably because of #2)

Hope this answers a few of your questions.


Edit: a couple pictures of my pryknife. You can see on the leading edge of the front (ground) side of the blade and bot edges on the back side have carbidizing on them to increase the surface hardness.

32jRW.jpg


32jSA.jpg
 
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I just wanted to second PigmonkeYs suggestion that the blades are most probably coated with titanium nitride. Titanium nitride is widely used in parts that require wear resistance, these include for example drill bits, milling cutters etc. Its primary use is in fact added wear resistance as it is a very hard ceramic substance and in some applications it does actually multiply the life of the part. If the entire blade is coated with TiN, including the edge, it will add some wear resistance and help keep the factory sharpness a bit longer. But such coatings aren't used in regular knives cause they are stripped away from the edge by the first sharpening job.
 
SM-100 (Nitinol) is not titanium in fact it contains more nickle than titanium. And yes it is expensive, but it is also awesome!
titanium alloys do not make for great blades, some alloys can work, but not as good as steel which is cheaper and easier all around
 
JustSomeGuy said:
why it doesn't get used for blade materials in knives.
Click to expand...
Titanium is used for making knives.
Its just often not Beta-ti being used hence ti knives has gotten a bad rep amongst some uses.
Few Companies are able to Work Beta-ti hence other grades are used.
I use Beta-ti knives as camp knives etc and they work just fine.
They take an edge suitable for the work.
My Beta-ti skinning knife is razor sharp and works just fine for zipping through several deer at a time without noticable loss of sharpness.
Further more the knives are very light weight and impervious to the elements which makes for a fine kayaking knife.






When kayaking in the Winter time, its good to know, that your knife will work when you need it to:



 
I agree that titanium doesnt hold up as a blade very well. Titanium is mostly used for coating knife blades for weather resistance. I also hear that the swords used in movies and sword fight demonstrations use titanium blades so that the blade won't actually chip or break and hurt one of the swordsman.
 
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Thanks for the responses, upon closer examination, the blades are "titanium bonded", i.e. TiNi or some such (they don't really specify). It'll be interesting to see how these hold up for her.
 
I've used an carried this little guy a fair bit. Edge is chisel ground, and carbidized on one side, it definitely takes an edge that's more toothy than polished, but that's kinda the nature of the beast. I really can't complain though, it's a great little knife, and I have every intention of buying more titanium blades in the future.

otterchizell3.jpg
 
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