Thread: Cryogenics - check it out...

Stream of thought... ok, here goes... I was thinking about why Dubl Duck Wonderedges command such a price over the other models (funny that the thread post in this topic forum under mine is just about that)... and aside from the pretty scales it seems that there is this cryogenically treated steel.... "Cryogenically" treated.... I wondered about that. Did it somehow harden the steel so that it can take a finer edge, or so that the edge lasts longer... or both?? I started doing some research online.

The first page I stumbled across was here.
http://www.madsci.org/posts/archives...3052.Eg.r.html

It talks about metal and fatigue.
To understand the term "fatigue" we will conduct an experiment:

• Straighten out a standard paper clip.
• Flex it a little and then let it go. You will notice that it returns to the straightened position. You could repeat this cycle many times (many years actually) without breaking (fatiguing) the metal because you are cycling the metal in its "elastic range" ( it has a memory similar to piece of rubber).
• Now we will bend (stress) the paper clip a lot further and you will note that it did not return to the straightened position. This time you stressed the metal in its' "plastic range" where it did not have a memory.
• If you bend the metal back and forth in this plastic range it will crack and break in less than twenty cycles. The metal fatigued more quickly because it "work hardened" and became brittle. The more you stress the metal by flexing it the quicker it will work harden and break.

This fatiguing has little to do with what happens to our razors, but it got me over to this page to understand how to prevent metal fatigue. http://www.madsci.org/posts/archives...3052.Eg.r.html

It talks about improving a steel leaf spring, but to summarize:
So to increase the fatigue strength of your leaf spring, you have to do
one [or more] of the following:

1) Carefully polish the surfaces of the springs to remove any surface
defects or machining marks that will be the location for crack initiation.
2) "Shot-Peen" the steel. Bombard the surfaces of the springs with steel
shot, which cold works the steel, which hardens the surface and puts it
into a state of compression, which impedes crack propagation.
3) "Temper" the steel. When initially forming the piece, cool the outer
surface quickly to put the surface into a state of compression, which will
also impede crack propagation.
(There's another definition for "Tempering" steel, which is heating it to
stabilize and de-stress the crystal structure.)
4) "Quench" the steel. When forming the piece, the faster you cool it
down, the more steel gets locked into a Martensite phase, which has better
fatigue properties. However, if you quench it too quickly, you develop
thermal stresses and cracks, which will obviously weaken the steel.
(Another method for increasing the Martensite percentage is to heat treat
the steel before tempering it.)
5) During fabrication, prevent air pockets or contaminants ("non-metallic
inclusions") from getting into the steel. These contaminants will provide
starting points for cracks to form.
6) Increase the carbon content from .5% to about .95%. This will harden
your steel and improve the Fatigue properties.

I started thinking more and more about #4 - quenching. I remember reading on the classicshaving site that many of the DOVOs are tempered with fire and ice. Or, if you've ever seen a blacksmith throw his maleable, hot steel into a tub of water to harden it's shape, you'll know what I'm talking about. I thought maybe this had something to do with the cryogenics of the wonderedge. Maybe they weren't using water, maybe they were using something colder. Like maybe liquid nitrogen....

Then I hit upon this page. http://www.kfor.com/Global/story.asp?s=3390503
Which even if you aren't into improving razors, is cool. This dude has a tub of liquid N2 in his garage (which he runs a business out of), and he has been dipping his car parts into it to harden them. His Honda Hybrid improved it's gas mileage from 50 to 120 gallons per mile somehow. HOLY SH*T!

Now he also, ODDLY!, mentions that he's even cryogenically treated RAZORS!
He even has a website for doing it. Check this guy out! He beat me to my idea!!!
http://www.greatrazors.com/

Of course, he only treats cartridge razors and double-edge blades, which leaves a nich area for me.
Now I was really salivating. For, as most of you don't know, being a graduate student in a science lab, I have access to lots, and LOTS of liquid Nitrogen.

I started thinking, what if I started cryogenically treating some straight razor blades - would they harden and have improved edge holding ability? Could this be a new business market? Would it be better to remove the scales and heat the metal razor blade on my electric stove burner until it's red hot, thus aligning the crystal structure of the metal (see tempering above), then cool it in water, then further cool it in liquid N2?? (I wouldn't want to cool it too quickly and cause it to crack). Obviously some experimentation is going to be needed.

On this guy's website, he states under his 'FAQ' section
What is the difference between a "Cryo'd" blade and a regular one?
Our Cryo'd blades last 3 to 4 times longer and shave better. The reason our Cryo'd blades last so much longer is that we Cryogenically Temper the blades down to -300 F, this makes the metal stronger and more durable.
How did you freeze these without opening up the package?
Our Cryo process is very gentle, the temperature is lowered very slowly. This gradual temperature drop does not damage the package. So we can Cryo the razors right in the package. Just like the items in your freezer, the package stays intact. And since they stay at -300 F for 24 hours the cold goes right through the package and treats the metal blades.

So it sounds like he's maybe not dunking the blades into the liquid N2, but just holding them in the tank with the liquid N2 vapor to gently freeze them to -300 for 24 hours. It sounds like the blades stay sharp much longer, so I think I'm going to try treating some, and then maybe ALL my razors this way if there aren't any negative side effects (like more difficulty in honing).

Hell, maybe I'll even open up a little bid'ness on the side for you nice folks over here.

You'd have to be carefull. Heating the blade can kill the temper as well since it's already been tempered. Retempering might not or might work. I'm not sure.

Quenching cryogenically makes the last of the austenite turn to martsenite. perfecting the overall quality.

Tempering and quenching only works if there is a lot of carbon in the iron. without carbon -> no hardness.

If a razor is already tempered and quenched, and all the carbon is bonded in martsenite, it is impossible to improve the hardness further.

Your results will depend on the existence of left over carbon. This will be variable, and might not make that much of a difference.
And of course there is the very real chance of warping the blade due to uneven heating and cooling.

The only time I would consider this is with a warped blade. then you could reverse the temper. press it into shape and treat it again.

Ok...
so maybe heating the blades up isn't necessary - they've already been tempered, so I wouldn't want to untemper them.

I'm not sure about how much carbon is left unbonded, but why do you think cryogenically lowering the temperature to -300 improves car parts, gillette DE blades and cartridge razors, but wouldn't improve straight razors?


FYI:
http://en.wikipedia.org/wiki/Carbon_steel
Silver Steel or high-carbon bright steel, gets its name from its appearance, due to the high carbon content. It is a very-high carbon steel, or can be thought of as some of the best high-carbon steel. It is defined under the steel specification standards BS-1407. It is a 1% carbon tool steel which can be ground to close tolerances. Usually the range of carbon is minimum 1.10% but as high as 1.20%. It also contains trace elements of 0.35% Mn (range 0.30%-0.40%), 0.40% Cr (range 0.4%-0.5%), 0.30% Si (range 0.1%-0.3%), and also sometimes sulfur (max 0.035%) and phosphorus (max 0.035%). Silver steel is sometimes used for making straight razors, due to its ability to produce and hold a micro-fine edge, as those made by the French company Thiers-Issard.

http://en.wikipedia.org/wiki/Cryogenic_tempering
Cryogenic hardening is a heat treatment in which the material is cooled to cryogenic temperatures to the order of -185 °C, usually using liquid nitrogen. It can have a profound effect on the mechanical properties of certain steels, provided their composition and prior heat treatment are such that they retain some austenite at room temperature. It is designed to increase the amount of martensite in the steel's crystal structure, increasing its strength and hardness, sometimes at the cost of toughness. Presently this treatment is being practiced over tool steels, high-carbon, and high-chromium steels to obtain excellent wear resistance.

http://en.wikipedia.org/wiki/Cryogenic_processor
Before computers were added to control cryogenic processors, the "treatment" process of an object was previously done manually by immersing the object in liquid nitrogen. This normally caused thermal shock to occur within an object, resulting in cracks to the structure. Modern cryogenic processors measure changes in temperature down to fractions of a degree and adjust the input of liquid nitrogen accordingly to ensure that only small fractional changes in temperature occur over a long period of time. The general processing cycle for modern cryogenic processors occurs within a three day time window, with 24 hours to reach the optimal bottom temperature for a product, 24 hours to hold at the bottom temperature, and 24 hours to return to room temperature.

http://www.dqsnet.com/cryogenicwear.html

Cryogenic Wear Resistance Improvement

D2 High Carbon/Chromium Die Steel : 817%
52100 Standard Steel : 420%
440 Martensitic Stainless : 121%

You can try the cryogenic treatment. But I'd stay away from heating the blade when It's not needed.

Originally Posted by fredvs79

Ok...
so maybe heating the blades up isn't necessary - they've already been tempered, so I wouldn't want to untemper them.

I'm not sure about how much carbon is left unbonded, but why do you think cryogenically lowering the temperature to -300 improves car parts, gillette DE blades and cartridge razors, but wouldn't improve straight razors?

Sorry. I wasn't saying that it wouldn't improve, but that it depended on the previous treatment. If the blade has already has previous subzero treatment (as some have) you will not get much extra hardness.

And heating them up would be pointless, since that stage was already finished, and reversing it would only increase the risk of a warped blade.

Btw, you'd also have to watch out for the scales. I am not sure that mammoth ivory or other things would survive the dip without fractures. Hm... interesting experiment. I suggest you give it a try and let us know.
After all, you'd probably be best placed to do an experiment.

Here's the scoop on this stuff...

Martinsitic steel relies on a transformation from Austenite to Martensite in order to create the hard, crystaline structure that gives a blade it's wear reisistance and fine cutting edge.

High carbon steels can only benefit from cryogenic treatement if not all the austenite was converted to martensite. This happens between room temperature and 400 degrees for straight steels. Double or triple tempering will usually convert the maximum amount of martensite.

I had a wade and butcher that went 57/58 HRC due to retained austenite cryogenically treated. It improved the hardness 1 point and that was that. If a razor has very little or no retained austentite then cryogenic treating won't help a bit. Interrupted quench processes, mar-quenching, aus-quenching, etc., are all designed to minimize the dimensional instability of the blade while maximizing martensite transformation.

It is considered a necessity to do any cryogenic treatment prior to the final tempering process. Cryogenic treating without additional tempering will introduce stresses into the blade that could ultimately cause it to spontaneously crack and break.

Cryogenics is considered a very good process to use for stainless steel, but it's generally considered either moderately useful or completley redundant for high carbon steels. As part of the full heat treat and temper, it can't hurt. As an aftermarket idea.... probably not such a good idea.

But...... that's just my take on it. I could be wrong. Lots of things in the metallurgical field are still debatable.

p.s., I wouldn't put a lot of stock in the following exerpt:

4) "Quench" the steel. When forming the piece, the faster you cool it
down, the more steel gets locked into a Martensite phase, which has better
fatigue properties. However, if you quench it too quickly, you develop
thermal stresses and cracks, which will obviously weaken the steel.
(Another method for increasing the Martensite percentage is to heat treat
the steel before tempering it.)

Here's why. The speed of cooling isn't directly responsible for the martensite transformation. While it is very important to drop high carbon steel from 1333 degrees to under 900 degrees in about 1/2 second, once that's accomplished, further shock to the blade is counterproductive, in my opinion, because once you have gone under the pearlite nose at 900 degrees, you made the most important goal in the cooling. Pearlite can't be transformed into martensite, so if you allow the steel to revert to pearlite it can't become martensite. The pearlite nose is a combination of the temperature and cooling time at which martensite to pearlite transformation takes place and if it takes more than 3/4 of a second to drop to 900 degrees, you have pearlite - a large grained soft crystalline structure that will not harden.

The martensite transformation, actually occurs at a much lower temperature and isn't dependent on quick cooling at all. Retained austenite that hasn't "set" can be converted for minutes, hours or days.

And the quote that "another way to increase the percentage of martensite is to heat treat before quenching......" Frankly, that's the only way to get martensite at all. Heat treat and quench.

Heat treating is more than just getting steel really hot and dumping it in a bucket of water. Cryogenic treating is also more than just taking steel and dipping it in liquid nitrogen.

There's a lot more to this set of arguments than generally makes the public eye.

Did you know that most, if not all, of the companies who promote this research are also in the business of selling the equipment? I'd call that a conflict of interest.

I'm with Robert on the subject of plain carbon (aka low alloy steels) vs. stain resistant ones (aka high alloy steels). If the heat treatment for LAS is correctly done, most if not all of the signficant austenite is converted to martensite, therefore no further benefit from cryo treatments will be obtained. Most, if not all, HAS's have very specific estimates of retained austenite and will likely improve from cryo treatment.

The rest is marketing hype.