Pair of 1095 Blades

[Mechslasher]

here's a pair of 1095 steel knives i just finished. the blade on the right was cryo treated while the blade on the left is regular 1095. i'm planning to see if the cryo treated blade holds an edge like it's advertised to do. enjoy!

 

[Jeremy]

Cryo treating 1095 isn't going to do much.  The only place cryo treating really comes into play is with the complicated alloys.  I've asked a few suppliers what they do to cryo treat their blades... most of them really don't.  You need to get it below -300 degrees to change the remaining austenite to martensite.  With the plain high carbon steels (1095 being one of 'em) there is very little remaining austenite after the normal heat treating, so a cryo treatment has nothing to do.  With the really high alloy steels the normal heat treatment may only convert 85-90%... the cryo treatment may convert another 5-10% if done right.  Many makers who claim "cryo treated blades" don't have the liquid nitrogen on hand to do it.  A commercial freezer just ain't enough.

Very nice job on the knives!!  I like the way the lines flow on the left.

[Leftieshot]

Jeremy, what steels are the more "complicted" ones you mentioned?  What does this treatment cost?  Who does it and what does it do to the blade for edge quality?

[Jeremy]

Leftie, the high alloy steels - O1, D2 and most of the stainless - may benefit from cryo treatment if it's done right.  That means getting the blade into the liquid nitrogen immediately following the normal heat treat to transform any of the retained austenite into martensite.  

That's all it'll do.  It doesn't relieve any stresses in the blades (as claimed by some - the x-ray diffraction data proves that).  For the high alloy steels it'll gain you a few more points on the rockwell scale, so a harder edge with better grain in the steel - assuming the the whole thermal cycling was done correctly in the blade to begin with to refine the grain structure.

For any of the 10XX series steels, L6, W2 or 52100 there's really no benefit.

I've never really looked into who does it or the cost, but since it should be done right with the heat treat I'd start by looking at who offers heat treament services.  All you need after that is liquid N2.

[Leftieshot]

I'm not disputting you Jeremy so don't take this that way, please.  I don't really see the benefit of cryo treatment.  Or its VERY expensive.  I say this because I've been a tool and die maker for 12yrs and I have yet to get any dies steels cryo treated.  Extremely hard steel isn't all that great in my opinion.  Its more brittle and possibly less stable.  I mean when I pull my blades (I use A-2 tool steel) out of heat treat they are 62-63 rockwell and if I temper them to be hard I can make them 60-61, that pretty darn hard piece of steel.  I temper mine back to 58 max.
Bottom line, I just don't see the benefit.  Especially since it doesn't make any more stable.  But I'm no expert.  Thanks for the info though.

[Jeremy]

I'm agreeing with you Leftie     Mostly, cryo treating is on par with edge packing - the hard data doesn't back it up (pun intended).

As I said in the first post, cryo treating the high alloy steels may help convert that last 5 to 10% of the retained austenite to martensite - not a whole lot of improvement, just evening the structure throughout the blade.  For most high alloy steels that would give you an additional point or two Rc.  Then you go and temper to draw it back to the desired hardness.  If there's marginally less of the retained soft austenite at the edge the blade will stay sharp marginally longer.
For the low alloy steels it doesn't do squat.

Far more important for any steel is the proper working temperature and thermal cycling to keep the grain structure under control.

[Leftieshot]

Well this is gonna be off subject a little bit.  Then how does it help rifle barrels?  I ask because they aren't even hardened steel.  And aren't even some of the higher alloy steel to my knowledge.  For example a stainless barrel?

Jeremy, I am nominating you to do thorough research on this cryo treatment and report back to us in depth but in simple terms the common man can undertsand.  Now go, get busy, time is wasting!!

Hahaha!!!

[el oso]

Very interesting.......I didn't understand any of it, but it sounded good.I do know that those are perty knives. I like the one on the right best.

[LC]

Ok I've been thinking and researching this. Heres my thoughts. It seems alot of folks do think it's worth while but not worth the cost. And I agre with Jermemy on simple steels who knows probably not! BUT heres what I'm thinking for the backyard builder. A man can buy the over the counter wart remover that's liquid nitrogen now adays. Lets say a back yard builder tempers a blade lays it in a notch of styrofoam and then sparys' it with  liguid nitrogen. That Sh#%# will freeze your finger in a New York minute so I'm wondering if that would work. You could line up several blade blanks and do them in bulk and I'd think a can of wart remover would do several blade blanks. Thoughts??

[Leftieshot]

LC, are you literally talking about using wart remover to cryo-treat a blade? If so I think you would be wasting your time and money on that product.  Its simply not cold enough.

[LC]

I respect your opinon Leftieshot but it's liguid nitrogen in a can just like skin docs use to freeze stuff. I'm thinking, just my opinion, if you cut a slot in stryofoam and lay your blade edge in it and spray the blade edge you could acheive sub freeing temps with it with out a doubt. Just my opinion though. This stuff will freeze your skin solid if you use it! It's not like ice but like dry ice in a spray can.

[Doug Campbell]

Hmm... assuming it would do any good and you really wanted to mess with it. If you are in Ag or ranching country there is probably someone around who artificially inseminates cattle or horses. The semen is stored in a tank of liquid nitrogen....

LC, to do any good your going to have to hold your blade at the low temp for a bit. Liquid Nitrogen evaporates very rapidly, assuming your wart remover is really liquid nitrogen I expect it aint gonna stay around long enough to do you much good. By the way this stuff in -320º how many inches of insulation is there wrapped around that can to keep you from freezing you hands while handling it?

[Jeremy]

LC, that amount of liquid N2 wouldn't be around long enough to do much of anything.  Looking up the protocols shows you want to drop the temperature slowly, hold it there, then warm it back up to room temp.

Leftie asked about gun barrels; depending on who you talk to it's not worth it there either.  The gun manufactures have put out reports saying it relieves stresses in the barrels and improves wear resistence.  The custom barrel manufactures (who would have the most to gain by selling cryo-treated barrels) have done the actual researh (the x-ray diffraction data I mentioned is mostly from them) that shows there is no difference in the molecular stresses or structures between a cryo treated barrels and properly stresses relieved barrels.  Putting matched barrels side by side in a shooting machine shows no difference in accuracy over several hundred shots either.

The hard data just doesn't back it up for the simple steels.  Even most stainless doesn't benefit greatly.  O1 and D2 seem to get the most from it, but the effect is negligible.

We've gotten a bit off topic - you did a nice job on those knives Mechslasher