60-NiTiNOL - Hype or...

Some before and after SM-100 wood chopping pics from the manufacturer & knife maker:

Source: http://www.summitmaterials.com/elliot-continues-to-punish-sm-100/
SM-100-chef-chopping.jpg

SM-100-chef-after-chop.jpg
 
I think I can help. I just made a small neck knife from the stuff, and its pretty cool. First off probably some 95% of NiTinol is used for its shape memory properties not its hardness or wear properties, so most of the literature is written about that. The SM-100 is essentially a PM 60NiTinol which meanes 60 wt% Ni, and 40 wt% Ti. 60NiTinol can exhibit shape memory capability, and very high hardness, just not at the same time. The heat treatment required to obtain these properties is different, so say goodbye to a super hard supperelastic knife. I think this might be where the confusion with the low youngs modulus comes from; I think the youngs modulus is reported for the unhardened state, because that is what 95% of people use.

The heat treatment for SM-100 is 1800 F for 30 min and a oil quench. I was able to obtain 59 HRc, but I quenched in the foil packet, and might have been a tad slow. Next time I will still leave the blade in the foil packet, but I will quench in water. The hardening mechanism for this material is the precipitation of TiNi3. While I have no data on edge retention, this makes me think that it is fairly favorable because it is hard, and full of very hard TiNi3 particles

As others have stated this material is absolutely corrosion proof. The only thing that will touch it is Hydrflouric acid. For a small neck knife that I plan on never taking off this is a must. Also it is slightly lighter than steel, another plus for a neck knife. Additionally NiTiNol will anodize somewhat. Some people are getting some awesome oxide patterns out of heat treat.
 
Thanks for that info. BTW, why did you foil wrap the blade? Is there an issue akin to decarb for this alloy?

Also, I want to mention I was being tongue in cheek about the 'throw it in the oven if it bends' part of my earlier post. I don't think anyone wants to expose handle scales or adhesives to elevated temps just to watch a bent blade straighten out. I had also forgotten a detail about the video I saw that inspired the comment - Gareth Bull said the shape memory was in the annealed state

[youtube]iFFLCfZg0r0[/youtube]
 
Nebulae said:
I think I can help. I just made a small neck knife from the stuff, and its pretty cool. First off probably some 95% of NiTinol is used for its shape memory properties not its hardness or wear properties, so most of the literature is written about that. The SM-100 is essentially a PM 60NiTinol which meanes 60 wt% Ni, and 40 wt% Ti. 60NiTinol can exhibit shape memory capability, and very high hardness, just not at the same time. The heat treatment required to obtain these properties is different, so say goodbye to a super hard supperelastic knife. I think this might be where the confusion with the low youngs modulus comes from; I think the youngs modulus is reported for the unhardened state, because that is what 95% of people use.

The heat treatment for SM-100 is 1800 F for 30 min and a oil quench. I was able to obtain 59 HRc, but I quenched in the foil packet, and might have been a tad slow. Next time I will still leave the blade in the foil packet, but I will quench in water. The hardening mechanism for this material is the precipitation of TiNi3. While I have no data on edge retention, this makes me think that it is fairly favorable because it is hard, and full of very hard TiNi3 particles

As others have stated this material is absolutely corrosion proof. The only thing that will touch it is Hydrflouric acid. For a small neck knife that I plan on never taking off this is a must. Also it is slightly lighter than steel, another plus for a neck knife. Additionally NiTiNol will anodize somewhat. Some people are getting some awesome oxide patterns out of heat treat.
Click to expand...

Thanks for the info! That's good to know about the youngs modulus.

Another knife maker is saying that the edge retention is "very similar" to ELMAX, and can reach a hardness of 65HRC, and does not sacrifice "durability, edge retention, wear resistance, or impact resistance." I hear the toughness is comparably high, too. For me, I am basically boiling it down to "which one's better overall?"... ELMAX, M390, etc... or SM-100.
 
No there is no decarb, or embrittlement, or anything that im aware of, but if you do it right and get lucky you can get an awesome oxide pattern like this
526209_196000890524869_1728290641_n.jpg
 
that is pretty nice, there is also that VECP with the funky yellow oxide which is very cool
 
Interesting. It's been ages since I first heard of that stuff in a Strider custom. Nice to see that it's more readily available now.

The prices posted earlier IMO are not out of reach. While they're out of the question for production knife runs, I think they're in line with custom orders, and possibly small sprint runs. Sure, the bar stock itself costs as much as a very good production folder, fixed blade, or auto, but quite a few of us already have a bunch of those.
 
Here's some info about NiTiNOL found on this site: http://www.tiniaerospace.com/smanitinol.html

I'm not sure which NiTiNOL variation / grade it is (I'm guessing the 55% nickel content).

smanitinol.html


Yield Strength (Austenite) | 560 MPa | (80 ksi)
Young’s Modulus (Austenite) | 75 GPa | (11 mpsi)
Yield Strength( Martensite) | 100 MPa | (15 ksi)
Young’s Modulus (Martensite) | 28 GPa | (4 mpsi)
 
An abstract from a research study on 60-Nitinol: http://www.bladeforums.com/forums/showthread.php/1052763-60-NiTiNOL-Hype-or?p=12039481#post12039481

Unlike other Nitinol alloys, 60-Nitinol does not require cold work. Initial testing of this material shows that the transition temperature is a strong function of the heat treatment. Therefore the same ingot of material can produce samples with superelastic and shape memory effect. Samples with different heat treats exhibited transition temperatures varying from -55 C to +60 C. Additionally, appropriate heat treatment allows the material to exhibit extreme hardness (Rc 63) or a two-way shape memory effect. This paper provides the first study of the thermomechanical properties, including stress-strain curves and thermal cycling, of axially loaded slender 60-Nitinol samples. The samples were tested at extremely high stress level greater than 695 MPa (100 ksi) with recoverable strain of 2.5%. In addition, flexures designed with potential for aerospace applications were tested. This initial research shows that 60-Nitinol has some enticing advantages over 55 Nitinol, however further study is required.
 
If it is indeed a good knife material, you better believe Spyderco will use it in a sprint run.
 
It has been around for a while the Navy had done a bunch of research with it back in the late 50's or 60's, as someone else said earlier it is essentially titanium that can be hardened. The catch is it can be hardened without becoming brittle or while retaining its toughness something which titanium is known for. John More the former owner at Mission Knives had looked into this stuff before he died, (may he rest in peace) and posted stuff on another site about just how impressive it was. However, the drawback then as it is now is price. The stuff Mission used in their knives the Beta Ti is basically the closet thing to this as was reasonable in terms of price, the only drawback while it all but corrosion proof with the exception of a small handful of the most caustic acids known to man and boiling seawater, tough beyond belief, John couldn't not raise the hardness beyond 47 Rockwell C. He said anytime he took it much further that the Beta Ti would become brittle, however this NitiNol material he said could retain all the positives of the Beta Ti material but be hardened to like 65-67 Rockwell C which is beyond impressive when you consider the other qualities of this material.

Its a good thing edge retention is what is, because sharpening this stuff has got to require serious skill and effort. Impressive material to say the least.
 
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