Cryo tempering

Rick and I have had this discussion on swordforum [where I go by Robert C] .The problem is that other than reducing retained austenite we're not sure what happens. Therefore we don't know how to deal with all the variables. Since Rick is on the cryo committee I hope he can get the industry to do more basic research .That will give the industry more credibility and be a help to us all .
 
Don Powell
I don’t see a real problem here. Have the blade quenched and tempered like you would always would. Then have it cryo treated with at least a 300F temper. Since primary martensite starts to temper at about 220F, the blade will not be brittle during shipping. Then have the heat treater temper the blade back to whatever hardness you desire. To get maximum properties, the blade should be tempered at least twice anyway. Something else to consider is that retained austenite is not very stable. Heat, vibration, flexing, or a cold day will cause it to transform to martensite. It’s better that you transform it and temper afterward than send a blade out and let it transform in the field.

That being said, the transformation of retained austenite as finished as it is going to get at about –140 F. So have the heat treater toss the thing in some dry ice and alcohol before the final temper if you are worried about retained austenite. Then cryo treat for the rest of the properties.

mete:
There are a lot of other proven effects of cryogenic processing Other things that have been proven to happen:

We are sure that eta carbides are being formed
(Cryogenic Treatment of Tool Steels; Collins, David N.; National Heat Treatment Centre, University College Dublin Ireland; Advanced Materials & Processes, 12/98 pages H23-H29 and The Role of Eta-carbide Precipitations in the Wear Resistance Improvements of FE-12Cr-MO-V-1.4C Tool Steel by Cryogenic Treatment; Meng, Fanju, Tagashira, Kohsuke, Azuma, Ryo, & Sohuma, Hideaki; Muroran Institute of Technology; ISIJ International, Vol. 34 (1994),No. 20, pages 205-210 ).

We are sure that cryogenic processing reduces residual stress, and not only in ferrous metals
(EFFECTS OF CRYOGENIC TREATMENT ON THE RESIDUAL STRESS AND MECHANICAL PROPERTIES OF AN AEROSPACE ALUMINUM ALLOY by Po Chen, IIT Research Institute, Tina Malone, National Aeronautics and Space Administration, et al.

We know there is a redistribution of alloying elements.
(The Change of the substructure Elements and the Redistribution of the Alloying Elements by Means of Cryotreatments in Alloy Tool Steels; Alexandru, I, Coman, G, & Bulancea, V; Scientific Society of Mechanical Engineers; Proceedings of the 5th International Congress on Heat Treatment of Materials, Budapest, Hungary, 901 to 908 )
We know that vacancies in the crystal structure can be driven out.
STRUCTURE-PROPERTY RELATIONS IN NONFERROUS METALS, Alan M. Russell, Kok Loong Lee, John Wiley & Sons, 2005, page 19.

It is absolutely proven that more is happening than retained austenite, as consistent results are achieved on cast iron brake rotors, which are pearlitic in structure. Also reference my company’s monthly newsletter which has given numerous examples of non-ferrous materials responding to cryogenic processing.

I agree that much more research needs to be done. Don't look for the cryogenic processing industry to do a lot of expensive research. They don't have the money, mainly because people will not use the process claiming that there is no research. For anyone out there that says there is no research, go to http://www.cryogenicsociety.org/publications/cold_facts/current/cryogenic_processing_articles.php.

The use of cryogenic processing on brakes is probably the best hope to for sparking research into cryogenic processing. It is a highly visible application that is saving significant money for fleets who don’t care that it “can’t work.” Once it becomes “normal” to cryo treat parts that have no retained austenite, some of the knuckleheads in the metallurgical community might take some interest. It is that interest and proven use of the process that will get people thinking. Either that or the foreign competition making better products using cryogenic processing. It is already happening. The Chinese are already making tooling using the process, and Europe is catching on quickly, especially in racing. They are not shy about using racing technology in their street cars.

By the way, I keep seeing the name OneCryo in this discussion. Would anyone object if I mention the name of my company and its website? I haven't done so up to now because I know it is bad form in a forum, but a competitor's name has been mentioned multiple times and they don't seem to be trying to help in the discussion. Also, I think some of you would get some insight if you look at our website. There is a lot of information there and you can sign up for our monthly newsletter which can help you keep abreast of the field.

Well, I've been very wordy again, so I best get some work done.

Best regards to all,
Rick
 
Are you in Park City, Rick? If so, I am located a few miles from you. Since you are being professionally ethical, I will point out to those interested that your company homepage is listed in your user profile. Hope you don't mind.

I'm surprised that with the potential improvements this offers anecdotally, there have been so few materials science departments at large universities all over this as a grad project. Of course, by anecdotally, I only mean in the refereed scientific research sense, not in any derogatory way.

BTW, do you have any idea why the Cryogenius article on the eta-carbides went "offline" into some password protected environment?
 
Fitzo:
Yes, we are in Park City in kind of a temporary plant there until we can see what the production requirements will be on a project we are working on. Thanks for pointing to our web page.

I've seen research on cryogenics from IIT, University of Northern Iowa, Purdue, University College in Dublin, Ireland, University of Trento in Italy, and others. The research done by Dr. Randall Barron was from a university. Most of this research was done on wear resistance either on a specific part or on wear testing machines. The research is pretty consistent in showing something is happening. What is needed now is to show why it is happening so that we can optimize the process instead of using our empirically developed profiles. We need to be able to show exactly what changed in the material and why. Lack of this knowledge does not preclude use of the process, just optimization.

I am at a loss to explain why the New Zealand Cryogenius web site is password protected. Even the home page is protected. Seems to me that they would want to have as many people as possible seeing the site.


Regards,
Rick
 
Thanks for the info, Rick. I didn't mean to imply there was no journal literature from academia, just that there is room for more; I am surprised that with the established efficacy in a variety of applications it hasn't developed much more interest from basic researchers. More materials chemistry and physics as opposed to engineering, is what I'm trying to say. As you said, the why behind the what. It seems timely for more vigorous post-doc work. I am sure it will come eventually as the commercial applicability spreads.

Thanks, again. If you would ever be willing to let me visit, I would truly enjoy seeing a commercial cryo facility.
 
". The research is pretty consistent in showing something is happening. What is needed now is to show why it is happening so that we can optimize the process instead of using our empirically developed profiles. We need to be able to show exactly what changed in the material and why. Lack of this knowledge does not preclude use of the process, just optimization."
Rick , that puts it in better words than I have , exactly what I meant in all my posts !
 
Rick. Your website is fascinating. I spent about an hour or so in there. I really liked the 'Cryo Excuses' page. I also learned quite a bit, especially the bit about that you don't just dunk the metal into the liquid nitrogen and hope for the best!
 
Fitzo:
I understand your bewilderment about lack of studies and I do tend to over document my answers. Its just a habit I got into in the earlier days when it was very common for people to claim that cryogenic processing was some sort of fraud. So if it sounded like I was critsizing your post, I apologize. I just want to leave no doubt in peoples minds that cryogenic processing is a serious process. More and more research is being done all the time. The trouble is how to steer it in the direction that will be most beneficial to the process. Most metallugical departments want to do some cross sections and hardness tests. We already know what those will show. So if you researchers are reading this, give us a call, and let's discuss what needs to be researched.

Mete and Andrew Taylor:
Thank you.
 
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