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What Does Cryogenic Processing Do?
Cryogenic processing makes changes to the crystal structure of materials. The major results of these changes are to enhance the abrasion resistance and fatigue resistance of the materials.
In general, the process seems to refine the crystal structure of metals and crystalline plastics. Although there has not been definitive research on the subject, the theory is that it crystal structures are not perfect. Some research shows that there are around 10 vacancies per cubic inch of metal in the crystal lattice. Also, some atoms are not ideally located in respect to their nearest neighbors. We believe that cryogenic processing makes the crystal more perfect and therefore stronger.
We have some evidence from work that we did with Honeywell on thin film magnetic memory chips. They found that our process relieved stresses between the layers, increased conductivity, and also there was some evidence holes in these very thin films (on the order of several atoms thick) were gone after processing. This indicated a shifting of atoms in the crystal lattice. Another indication is that metal objects transmit sound or vibration differently after processing. We repeat that this is just theory and requires verification.
In Ferrous metals, it converts retained austenite to martensite and promotes the precipitation of very fine carbides.
It has been known for many years that cold will cause retained austenite to change to martensite. This can be verified through publications such as Machinery's Handbook, ASM's Metals Handbook and more. Even the best heat treating facility will leave somewhere between ten and twenty percent retained austenite in ferrous metals. Because austenite and martensite have different size crystal structures, there will be stresses built in to the crystal structure where the two co-exist. Cryogenic processing eliminates these stresses by converting most of the retained austenite to martensite. This also creates a possible problem. If there is a lot of retained austenite in a part, the part will grow due to the transformation. This is because the austenitic crystals are about 4% smaller than the martensitic crystals due to their different crystal structure.
The process also promotes the precipitation of small carbide particles in tool steels and steels with proper alloying metals. A study in Rumania found the process increased the countable small carbides from 33,000 per mm3 to 80,000 per mm3. The fine carbides act as hard areas with a low coefficient of friction in the metal that greatly adds to the wear resistance of the metals. A Japanese study (Role of Eta-carbide Precipitations in the Wear Resistance Improvements of Fe-12Cr-MO-V-1.4C Tool Steel by Cryogenic Treatment; Meng, Tagashira, et al, 1993) concludes the precipitation of fine carbides has more influence on the wear resistance increase than does the removal of the retained austenite.
Note that the hardness of a piece of metal becomes more even during the process. When multiple hardness readings are taken before and after the process, the standard deviation of those readings will drop a significant amount.
The process relieves residual stresses in metals and plastics
This has been borne out by several research projects as well as by practical use. We have customers who cryogenically treat metal before heat treat to reduce the distortion of the metal during heat treat. NASA is one of them. We processed components for the space shuttle's robotic arm for this reason. Gage makers have used cold temperatures to stabilize metals for years. Our work with Honeywell also showed the process relives stresses.
Cryogenic Processing is not a substitute for heat-treating.
Cryogenic processing will not in itself harden metal like quenching and tempering. It is not a substitute for heat-treating. It is an addition to heat-treating. Most alloys will not show much of a change in hardness due to cryogenic processing. The abrasion resistance of the metal and the fatigue resistance will be increased substantially.
Cryogenic Processing is not a coating. It affects the entire volume of the material. It works synergistically with coatings.
You cannot wear cryogenic processing off a part. It is there for the life of the part unless that part is subjected to such temperatures that it is brought up to the austenization temperatures. Unlike coated tools, a cryogenically treated tool can be sharpened, dressed, or modified. The change brought about by cryogenic processing is permanent.
The process works synergistically with most coatings. This is because coatings generally work by decreasing the coefficient of friction and by preventing metals from galling. Coatings start to fail when the metal underneath them fails. It is not unusual to find wear particles with coating on one side and base metal on the other. The coating did not fail; the base metal under it failed. Cryogenic processing keeps the metal under the coating from failing while the coating protects the metal.
What Can Cryogenic Processing be Used On?
Cryogenic Processing has a great effect on High Speed Steel cutting tools. The normal result is that the tools will last considerably longer, typically 2 to 3 times longer.
Carbide
Carbide cutting tools generally see a two to three times increase in life.
Works on coated and uncoated tools.
Works on solid, indexable, and brazed.
Drills
Taps
Lathe Tools
Shaper Bits
Cut Off Tools
Hobs
Saw Blades
Punches
Dies
Shear Blades
Slitting Knives
Steel Rule Dies
Skiving Blades
Chain saws
Broaches
Milling Tools
Router Bits
Almost Any Cutting Tool

We can cut your consumable tooling costs in half.

Both carbide and high speed steel cutting tools show significant life increases. Cryogenic processing is an excellent method of stretching the perishable tooling budget of large or small companies. Typical inserts cost $2.00 to treat.

The pictures at the right show carbide inserts that were on the same milling cutter. Notice the difference in the wear. This is a very rugged test because the treated insert had to take up the slack as the untreated one wore out.

Cryogenics and Coatings
Cryogenic Processing works synergistically with coatings such as Titanium Nitriding (TiN). Coatings act to reduce the coefficient of friction between the tool and the metal being cut. They also act a s a barrier so the cutting tool does not weld itself to the part. Coatings typically do not fail by wearing off. The material under the coating fails due to repeated stress. Cryogenic processing acts to delay the failure of the material under the coating and therefore protects the coating.

The use of cryogenic processing on high speed steel tooling is well known. High speed steel taps and end mills, drills, reamers, shaper bits, and broaches all respond to cryogenics. Typically, broaches will broach 3 times as many parts before sharpening is necessary. When sharpened, only 1/2 the amount of metal needs to be removed to achieve a sharp edge. This greatly increases the total number of pieces that a broach can cut in its lifetime.