Cold treatments, or subzero treatments, have been around for quite some time. Machinery’s Handbook describes the use of dry ice as far back as at least 1981. This article talks of using temperatures of -120F. There are stories of Swiss watchmakers burying newly made parts in snow, and it is well known that companies would “age” castings by putting them outside during the winter. Pierce-Arrow was one that was known to do this for their engine blocks. (Pierce had a definite advantage being in Buffalo, New York where it is known to get quite cold.) Also, I have talked to Indy car builders who claimed that their fathers would age castings in a similar manner before using them to make racecar engines. In a similar manner, the founder of Controlled Thermal Processing, racer Jim Birks, found that engines that had been in junk yards for a long time made superior race engines compared to brand new engine blocks. That is what caused him to look into the use of cold for making metals last longer. He found the existing research on the subject, which led him to start Controlled Thermal Processing.

We’ve traced cryogenic processing as far back as the 1930’s where the Junkers Company in Germany used it on components of their Jumo aircraft engines. We got this from a fellow who worked with an ex-Junkers engineer by the name of Adolph Luerker. Mr. Luerker immigrated to the US after the war and ended up in California working for McCulloch Chain Saw Company. He suggested that they use the process on chain saw blade links. They did and started Cryo treating their chainsaw blades but kept it a secret so other manufacturers could not make better blades. This was around the mid 1950’s.

Cryogenic processing had its US origins at the Watertown Arsenal Watertown, Mass. during World War II under the guidance of Clarence Zener, who would go on to develop the Zener diode among other advances in solid-state physics. The method was straightforward. Steel cutting tools were immersed in liquid nitrogen for a brief period of time, removed from the liquid, allowed to warm up, and placed into service in the arsenal’s production lines. Occasionally tools would crack or chip as a result of the thermal shock associated with the rapid rate of cooling. Some tools also became brittle because of the newly formed, un-tempered martensite and chipped in service. Of the tools that survived this crude quenching, many exhibited dramatically enhanced service life.

We found one person who claimed to have a razor blade and knife company in the 1940’s that used the process. The process used was a basic throw the blade into the liquid nitrogen situation and hope for the best situation.

We found a reference to cryogenic treatment in a magazine article as far back as the July, 1957 edition of Tooling and Production Magazine. Then, several people picked up the thread in the early 1970’s. The most notable and persistent was Dr. Randall Barron of Louisiana Technical University. Dr. Barron has written multiple research papers about the subject, as have some of his students. These papers are widely cited in the cryogenics industry.

Another early pioneer in the industry is Dr. Hugh E. Trucks. Dr. Trucks was a design specialist at General Dynamics Corporation and was later a private consultant. He wrote several articles on the subject, notably one for Die Casting Engineer, September/October, 1988. Dr Trucks was also affiliated with Cryogenics International, of Scottsdale Arizona. Dr. Trucks passed away several years ago.

A third pioneer is Ed Busch, who founded Cryo-Tech, Inc., who has been preaching the industrial use of cryogenics for over 30 years. He found the process hard to sell to industries that had never heard of it. He was also an important force in making the process available to industry. Cryo-Tech also funded some of Dr. Barron’s research. One has to admire his tenacity. Cryo-Tech was eventually bought out by 300 Below which gives rise to their claim that they are the oldest cryo company around. We find this amusing since both Controlled Thermal Processing and Applied Cryogenics processed parts for 300 Below during its start up.

Several things had to come together to make any invention work well. In the case of cryogenics, the following had to happen:

  1. A way had to be discovered to create intense cold
  2. A way had to be established to control the temperature of the cold chamber in a reproducible manner.
  3. There had to be a realization that changes could occur even at very cold temperatures.
  4. The change had to be tested. This involved having a means of testing and being able to eliminate the possibility of other random changes in the process.

It is obvious that the process could not exist even on an experimental basis until it was possible to achieve temperatures that were considerably colder than the earth’s climate allowed. Remember we have not had extreme cold available to us for very long.

A good history of cold can be seen at http://www.pbs.org/wgbh/nova/physics/milestones-in-cold-research.html.

Some documentation shows that artificial refrigeration occurred at the University of Glasgow in 1748. William Cullen’s work relied on the vapor-compression refrigeration process explained by Michael Faraday. It was not until 1845 that refrigeration units became available, strangely as a cure for malaria. It seems a Dr. Goerie felt that malaria was the result of bad air, and if he could condition the air malaria would not occur. Wrong cure, but it did advance the art of cooling. The first ones were only capable of making ice. The discovery by Cailletet in 1877 that gasses could be cooled by sudden expansion and the discovery by Pictet of the cascade cooling method led to Sir James Dewar’s research which led to the discovery that air could be liquefied and stored in Dewar flasks. While different processes were investigated until the late 19th century, Carl von Linde’s invention of a continuous process of liquefying gases in large quantities formed a basis for today’s refrigeration technology. The almost simultaneous invention of air liquefaction processes in Britain, Germany, France and the United States led to the production of liquid gasses in quantity. This happened in 1895. The science of refrigeration had to develop before the process could go ahead. It was not until the mid 1930’s that refrigeration got to the point where economical quantities of liquid oxygen could be made. For a long time, the liquid nitrogen, which was a byproduct of the liquid oxygen production was simply vented to the atmosphere.

A second item that had to occur was the invention of some way of ramping temperature down on a part in a controlled manner. This tended to be expensive and cumbersome before microprocessor controls became available. It was the invention of the microprocessor controlled temperature control that really made it possible to get repeatable results in cryogenic processing. Another item that needed to be added to the mix was the tempering phase of the process. Often those who dabbled in cryogenics ran into the brittle behavior of the processed metal, and decided that the cold had crystallized the metal, and that all was lost.

Another thing that hindered cryogenic processing of materials was that intuitively, one would not think of materials changing due to cold. After all, you heat treat metals, with the emphasis on heat. Archeological evidence shows that humans have been using heat on metals for over 75 centuries. Extreme cold has only been available for roughly 100 years. So it is almost intuitive that you use heat to change metals not cold. Yet even the most basic texts on metallurgy describe the temperature dependence of point defects in the crystal structure of metals.

Many people mention the fact that cold tends to inhibit chemical reactions, not promote them. The chink in that armor was that you get austenite to change to martensite when exposed to cold temperatures. Also, It is not unusual for companies to “season” castings for about a year or so before machining them by putting them outside and leaving them. The change was more associated with time than temperature though, and most likely the reason for putting them outside was because there was no room to keep them inside. If you are resistant to the idea that cold can make things happen, consider this: Super conductivity is created by cold. Something changes at near absolute zero temperatures that causes metals and ceramics to behave differently. Another thing had to happen in order to make people think in terms of cold changing things. The changes had to be detectable. Even into the 1940’s measurements were not precise enough to indicate changes caused by cryogenics. Processes were not controlled well enough to be able to say with certainty that the change was a direct result of the cold. A cutting tool may last twice as long, but that was easily put off to the effects of how it was ground or the variance in cutting geometry. Given that there could be large differences between one piece and another, the benefits given by the process could always be attributed to the production differences. . Once Dr. Deming taught us to control our processes closely, we began to be able to detect other things that could drastically change the production process. I still run into this today when working with carbide inserts. After showing double or triple the life on the insert, the comment most often heard is “Its normal to have variation in carbide inserts.” One wonders why people go to the trouble of testing the process if it is only to deny what they see.

It is important to realize that this process has been largely empirically developed. The reason is that it has not been researched deeply by large corporations or by government bodies with deep pockets. Even Dr. Barron’s published works go largely to the results of the process rather than how the process works. As Dr. Levine of Applied Cryogenics, Inc. in an article written in August 1998, says, “We just were not knowledgeable enough to realize that it couldn’t possibly work, so we worked with it and found that it did work.” The process is in need of research to optimize its results.

ASM International, the metallurgist’s and materials scientist’s professional society started a committee on the process in the late 1990’s. This committee was founded when members started to complain about the outlandish claims made by some of the early companies that were formed to promote the process. Claims such as “No one has ever blown up a cryogenically treated engine.” and “Increases the strength of steel by ten times.” did a lot of harm to the process. The committee also strove to create a database of research and articles about the process, and promoted sessions at ASM conferences that featured cryogenic processing.

About the same time that ASM got into the act the Cryogenic Society of America stepped up to the plate. They have been a great help in publicizing the process in their house magazine COLD FACTS, in directing companies towards responsible cryogenic processors, and in debunking outlandish claims. Both CSA and ASM have been very important factors in restoring the public confidence in this wonderful process.

Note

Controlled Thermal Processing is proud to work with researchers from such institutions as Illinois Institute of Technology, the US Army, Los Alamos National Laboratory, Honeywell, and others. We have also helped by supporting research on the high school and grade school level. We are currently sponsoring research at the University of Texas. We will consider providing cryogenic processing for any valid research project.