"Cryo" Tempered Razor Blades for Longer Life?? 1

[wdornfeld]

I was web-shopping for cheap Gillette Mach3 razor blades, and ran across the site

http://greatrazors.zoovy.com/category/xx/

that advertises long lasting razor blades that are simply Gillette blades that have been cooled to -300°F for 24 hours (in the original box, no less! Read the site FAQ.)
Question is: Does this make any possible sense metallurgically? TNX

 

[priyasachin]

Priyasachin,

dear friend,

it does make sense. in high carbon steels with or without alloying elements like chromium, the quenching for hardening leaves some residual auatenite in the structure. in hss tool-steel hardening and tempering it is common practice to deep freeze, a treatment similar to what you are refering, and then retemper it to reqired hardness level. the deep freezing treatment converts the residual austenite to martensite which on the second tempering will result in material which is hard and would remain un distorted. however, for very thin material like razor blade material, it is a matter of argument whether this treatment would give any additional benefit, except as an advertisement gimmick to attract people like you and me to interact.
regards,
MRCN

 

[BRT549]

There was a recent thread on the subject of extending razor life here. As I recall, it was one of the more interesting discussions I'd ever read on eng-tips. You might try a search for that . . .

 

[metman]

The section size is actually not relevant if there is retained austenite at the finished quenching temperature. If the Mf (martensite finish temperature) is below the lowest initial quench temperature, then cooling below the Mf will transform the retained austenite and will make the steel harder.

Jesus is THE life,
Leonard

 

[wdornfeld]

Thanks all for your replies. Since the blades remain in their sealed boxes, the cooling and warming rates must be essentially as in air. It is good to hear that this isn't apparently a scam.
BRT549 - I did find the thread338-53716 "Keep razor blades sharp" once I opened up my search to all forums. It was pretty interesting. Thanks.

 

[BRT549]

Yes, it was on the corrosion engineering page, not the metallurgy page. I see some folks resurrected it with some new posts. Very funny . . . . . .I'm an electric razor fan myself.

 

[mdighe]

I have come across a process called Cryotreatment. It is not similar to the deep freeze usually done after HT. This process is more involved and consists of cooling the part to about -320F at a controlled cooling rate, holding for 12-24 hours and bringing it back to room temp. at a controlled rate. The cooling rates are very critical for teh success of the process. The exact metallurgy of this process is not known. It is said to increase fatigue, wear properties in ferrous and composite materials.

 

[metman]

I was wondering when someone would refer to this. there have been many claims about cryotempereing or cryotreatment in recent years including just about any material imaginable from hairpins to musical instruments with claims of improved musical quality etc etc much of which could be subjective evaluation.

Some of these claims could very well be true but I remain skeptical of all of these claims except the tried and true and explainable/measurable transformation of retained austenite to martensite by suppressing the temperature below the Mf. The rate of temperature change is somewhat irrelevant for this since the phase change is not time dependant.

This comment about cryo is partly the cause for my skeptsism: "The exact metallurgy of this process is not known." But of course this does not invalidate it only calls into question the veracity.

Sometimes perception is worth more than truth so if it works for you go for it but you won't find me spending money towards cryotreatments until I see something substantive. I also might be forced to agree someday that UFO's are what they are puported to be.

Jesus is THE life,
Leonard

 

[IFRs]

I started Thread 338-53716 and boy has it been fun!! I happend across this one and just bought a package of cryogenic blades ( for scientific purposes only of course!! ) Maybe I can combine the ideas of the two threads and get maximum life from my blades with minimum nicks.

 

[wdornfeld]

I just ordered my Cryo's - let's compare notes to see how they perform. Even with shipping, they aren't that much more expensive than the non-Cryos in the stores. The prices are starting to make electric shavers look pretty competitive. But I miss my old Braun with the non-pivotting head.

 

[toolsteelmet]

In the tool steel heat treating market, cryo treating is a commonly promoted process. (It is most commonly promoted by its purveyors....) The "explanations" of the process are thin on substance. Our view has generally been that as some assurance of full transformation to martensite, the process has some definable benefits, and it has no detrimental side-effects (except perhaps to your wallet.) We have run some mechanical property tests on steels treated identically with & without, and have found no measurable differences. The rationales advanced concerning carbide precipitation at cryogenic temperatures seem at odds with classical thermodynamics. We have finally taken the position that just because we do not understand a process, it is not necessarily bunk. We just can't explain why it works (nor can the processors explain either why, or when, it works.)

 

[TSS]

I had a project investigating the claims of cryogenic treatment of materials a few years back when we had a research group at the company I work for (Fortune 200). We saw some pretty good results with different ferrous and non-ferrous parts. One that stood out was a 4140 plate that usually processed 20 million parts before being so worn down it needed replacement. This part was previously tempered to Rc 34 and we saw no change in hardness after the treatment. After the cryo-treatment, it ran over 120 million parts and still hadn't worn out before the project ended. (It actually outlasted our research group.) We saw copper welding tips for robotic weld lines experience 3 time their normal life and numerous punches for punch presses either double or triple their life as well. Our company thought enough of this to buy a chamber and treat our own parts. I've attended some conferences on this and read a good deal of the published papers (not advertisements from cryo-treaters). Some have pointed to eta-carbides forming in steel but you really need a TEM to see these which we did not have. You cannot see any change in the microstructure and the SEM was not useful in spotting any differences either. I wanted to try atomic force microscopy in the tapping mode looking for hard domains, but never got the opportunity. It also worked great on carbide cutting tips (6 - 8 times the normal life in a blind test in one of our factories). We had some x-ray work done on the carbides and saw some carbide phases form that weren't there previously. The bottom line here is that I'm not suprised to hear it works for razor blades. By the way, the fellow who first discovered this was a professor in Lousianna, I think, by the name of Randall Baron.

 

[unclesyd]

I've had great results with "Cryo" treatments for over 25 years. We used a "Cryo' treatment on D2, H-11, and H-13 tool steel components to eliminate retained austinite tranformation, growth. We could either used multiple tempers (6-9) or "Cryo" to accomplish this. We had to maintain close tolerances required while operating at 600°F and regular excursions to 900°F for cleaning. When we started "Cryo" treatments it became evident that we were also gaining wear resistance of the components. The best reaults from any "Cryo" treating came from treating extremely small, .003"-.009" dia. tool steel broaches. The number of holes/broach quadrupled to up to 10 times based on the steel used.
History: Swiss watches makers took thier die steels high in the Alps and aged them for several years prior to finish machining. Henry Ford aged his Motor blocks outdoors for several winters prior to finish machining.
As for edges I've treated an awful lot of knife blades and received good reports from nearly all. I've seen gains of up to four points in HRC,two points would be the norm. Wood carvers worried me to death. Prior thermal history will modify the results.

 

[Tooley]

Hmmmm interesting thread.... an old barber taught me that if I soak my facial hair for 5 - 10 minutes (at the ende of a shower) and then shave, the hairs will have soaked up lots of water and then become very soft, and the razor blades will last for ages.

I buy a pack of elcheapo gillette disposable razors, and each razor lasts about 2 -3 months of daily shaving.

1 pack of 12 razors lasts about 3 years.

Not bad value for a couple of bucks.

 

[SMF1964]

This is fascinating. One comment I might add is that the blades used in razors today are stainless steel. How does the cryo-cooling process affect this material?

 

[JTreglio]

Razor blades are made of martensitic stainless steels, so if the effect is to reduce the retained austenite, it should be valid for razor blades as well as tool steels.

On the possibility of other effects, I worked for many years in the ion implantation field. In ion implantation, atoms (actually, ions) bombard a surface with enough energy to penetrate a tenth of a micron or so, forming a new compound or alloy on the surface. The process results in a large increase in wear resistance -- two to three-fold. For many years, this increase was attributed to the surface alloying. The problem here is that the surface layer is very thin, so thin that it is removed in the first millisecond or so in a normal metal cutting application. Moreover, implantation with inert gases also produces improvements in wear resistance. Nonetheless, this remained the explanation given even in scientific meetings for over twenty years, until Russian researchers looked closely at the situation. They were able to discern changes in the microstruture caused by the bombardment down to hundreds of microns, with a region ten to twenty microns thick having high concentration of helical dislocations. The effects were very similar to those observed in a metal that has been deformed. Further, the improved wear resistance was found to depend on the depth of the helical dislocation structure, and independent of the thickness of the alloyed layer.

We looked at this issue from the stress point of view, found significant stress and strain changes induced by the ion bombardment. The strains were for the most part increased, but stresses varied depending on ion species. We found correlation between the strain increase and wear increase. In metals, we could not find a correlation between stress and wear resistance.

While these studies were carried out a decade ago, widely presented at technical meetings, with numerous articles in refereed journals, there are still practitioners that claim that the increased wear resistance is related to the alloying affect. So do not be surprised if those selling cryogenic processing don't have the foggiest idea of how it works.

Jim Treglio
Molecular Metallurgy, Inc.

 

[Frederick]

Researchers at Los Alamos National Laboratory, Illinois Institute of Technology, NASA, University of Trento, and others agree that cryogenic processing works. They also agree that they do not know precisely why. The austenite to martensite transformation has something to do with it with to respect to hardenable steels, but this does not explain why cryogenic processing works on copper, low carbon steel, austenitic stainless steels, etc. The carbide precipitation has been measured by Dr. David Collins at University College, Dublin, Ireland, and his article was published in Advanced Materials and Processes, the ASM magazine.

Cryogenic processing works. The research shows it. The more industry uses it, the more we will learn about it. To those who will not use it because they don't understand it, I point to the Wright Brothers. They did not understand why their airplane flew, as their brilliant work was empirical. They made observations that under repeatable circumstances, they consistently got the same results. It took another 25 years to figure out why the plane flew, and even may current explanations are not correct.

The point is that cryogenic processing will give consistent results. It could save industry a fortune.

 

[swall]

Frederick--I am familiar with David Collins's article. But, are papers on cryo research available from any of the other institutions you cite (Los Alamos, IIT, NASA,etc.)?

 

[NickE]

I'll agree w/ Frederick, but have to say It's hard to buy snake oil even if it works. I'm realatively new to industry. In school significant time was spent on the 1st principal basis for various [structure/processing/properties] techniques, whether ion-implantation, (TEM example), carburizing, Q&T hardening. Aside from the retained austenite factor no fundamental explanation has been given for why cyro-treatment works. I've seen some BS, (reduction of micro-cracks in grey iron)and some hard to discredit sources (LosAlamos etc...) but still sounds like snake oil to me.


(all our steel tooling is cryo-treated as part of the heat-treating, likely retained austenite, but does also provide some dimensional stability, I'm still amazed that air-hardening steels will retain austenite thou.)

nick

 

[Frederick]

All the papers I cited came to me from various sources. The University of Trento paper was published in the Journal of Materials Processing Technology, 118 (2001) pages 350 to 355. Title: Effect of deep cryogenic treatement on the mechanical porperties of tool steels. A. Molinari, M. Pellizzari, et al.

The IIT study was on gear materials and done for the US Army Aviation and Missile Command by the IIT Research Institute. I have the Briefing from June 13,2000 by A. Alan Swiglo. Also, there was a recent Master's Thesis by Rajenda M. Kelkar, A Study on Effect of Cryogenic Treatment on M2 Tool Steel for the Thermal Processing Technology Center under Dr. Phillip Nash.

The Los Alamos study was done by Yuntian Theodore Zhu and presented at the Thermal Processing Technology Center at IIT on June 4, 2001.

I hope that helps. You can also contact me if you like. I forget if this forum allows email addresses, so I will not give mine, but if you do a search under cryogenic processing, you will find Controlled Thermal Processing, and you can email me there.

NickE:
A repeatable but unexplainable phenomonon is not snake oil, it is just not understood. To label it snake oil is to call reputable researchers liars and con men. Calling us (yes, I research cryogenics) liars is not a good way to discuss or advance science. If you have research that will refute our research, by all means bring it forth and let's discuss it like gentlemen. If you think our methods were somehow bad, show us the error of our ways. Otherwise science will regress into silly insult games. By the way, your mother wears combat boots!

Cryogenic processing is process that gives reliable and repeatable results. It has nothing to do with snake oil. If you deal with a reputable company that has the proper metallurgical staff, you have nothing to worry about. If you deal with someone who bought a cryo machine to become rich, and does not have the foggiest of metallurgical ideas, you will get what you paid for. The same could be said about heat treaters, welders, etc.