[owlhause]

I just returned from a art fair. While I was there a man handed me his buisiness card...it was for 'cryogenic processing'....at first I thought he was going to try and talk me into freezing my head when I die! He then proceeded to explain that he has been using the process to 'freeze' carving tools for carvers the end result being the edge of the tool remains sharp for long periods of time without being sharpened....months without having to be sharpened. He went into details dealing with molecular structure and such which went right over my head...anyway....has anyone heard of this or had any experience with it? I think I'm going to send a new 'v' tool and have it done to see if its true...I'll post the results in the future!

Greg

[Hi_Ho_Sliver]

yep...they freeze all kinds of things...even engines! I have a set of 4 stainless blades that were frozen....really tough! I don't know why but it works..something about the molecules lining up? :P

[Baldy]

What would it do to the tool to stick it into a chunk of dry ice and let it stay there until the dry ice melts (I think the correct term is sublimates)? Is there a time frame or exact temperature that is critical!

Baldy

If you live in a fairly large city, you can locate a industrial gas supply outfit and they will sell you some liquid nitrogen. All you need is a thermous with a hole drilled in the cap so gas can escape without blowing 'er up. Last botlle I got was $5.00. I hauled it 75 miles and was still there when I got home.

Liquid nitrogen is much colder (boiling point -195.8 C) than dry ice (melting point -78.5 C). Â*I would think that might make a difference.

[mdallensr]

Where's Captain Bandaid when we need him? The cold quench they're referring to completes a phase transformation in the steel. We all know how steel hardens when it's quenched from a high temperature, but that process is not always complete. There can be some un-transformed austenite (the soft, high temperature phase of steel), that doesn't transform into martensite (the hard, 'room temperature' phase) until it reaches a very low temperature. Austenite is soft, non-magnetic, e.g. austenitic stainless steel, 300 series. If you transform all of the austenite to martensite, you'll reach maximium hardness, then you can temper the steel a bit to regain some of the toughness. The best example of this strage behavior was the Liberty Ships we built in WWI, which broke apart and sank in the freezing North Atlantic ocean. That final freezing quench in the ocean made the hulls very hard and brittle. The ductile-brittle transformation temperature can be as much as 100 degrees below zero, so you need to get your tools really cold to be sure you've completed the process.

I asked a question about a Cyroprocess in Jan 2004 on the woodcarver list. It is still in the Archives. The most comprehensive info was posted by Joe Dillett and I have included his response. This friend of mine who had some tools done things it was worth the money but has not had any more done. So don't know if that means it was not worth it or not. So here is the response from Joe Dillett.....
Gene

You're correct in saying this Cryoprocess needs more than a simple freezer.
Back in the early 1960's when I worked at Gisholt machine tool in Madison
Wisconsin, we did a cold process that was required for the military, using
dry ice in a large insulated box. This, I found, is not the same as the
Cryoprocess.

Part of what I found out is that the crystal structure changes in the metal
with the Cryoprocess. Among other things it completes the process of
changing the crystal structure from austinite to martinite (not sure about
the spelling). So for metals, such as A2 that is air quenched after the
1,500 degrees F heat treating, the air quenching doesn't turn all austinite
into martinite but the Cryoprocess does. Metals such as O1 are oil quenched
converting almost all austinite into martinite so the Cryoprocess has little
or no significant effect.

The Cryoprocess uses liquid nitrogen with about a 20-hour cooling down and
20-hour warm up cycle. Any carving tools would need the handles removed
because they finish up with about a +300 degree F.

Plastics are also effected (but not finished off with +300 degrees F).
Cryoprocessed golf balls are illegal for PGA.

As to the question about taking longer to sharpen, the answer is yes. If the
tool has increased toughness through Cryoprocessing it will have increased
toughness, more scratch resistant, in sharpening. However I'm told that the
increased sharpening time will pay bigger dividends in staying sharp longer.

Will it help our carving tools? Don't know, because the manufactures of
carving tools don't freely give out information about their metal and
process. We'll have to test each manufacturer to see if Cryoprocess improves
edge toughness. Because edge quality is quite subjective, standards for
sharpness have only recently been established, I suggest a test to see if
Cryoprocessing improves toughness which could be done in a comparative
lapping test. If it takes longer to lap after Cryoprocessing than we can
assume a more durable edge results from Cryoprocessing.

When asking if perhaps our carving tool manufactures are already doing
Cryoprocessing, the answer is probably not because if they were they would
be advertising it as another marketing benefit.

[owlhause]

Thanks for the info.
The gentleman offered to proccess 2 tools free of charge so I don't have much to loose.
I hope it makes a noticable difference as I despise having to stop carving to sharpen.
I believe I'll send him two 'v' tools...my sharpening nemeisis

Greg

There was a little clue in Joe Dillet's response, ' Metals such as O1 are oil quenched converting almost all austinite into martinite so the Cryoprocess has little or no significant effect. ' A good many carving tools and knives are made using 01.

And to think when I was in the calvary I hauled a semi-trailer full of liquid nitrogen bottles down to the shop, they used it in the thermal sights on the tanks.