Deep Cryogenic treatment of M2 Tool Steel

• The changes in the tensile strength and wear resistance resulting from cryogenic treatment
• The mechanism behind any property changes
• Model the phenomenon

From time to time over the last few decades, interest has been shown in the effect of low temperatures during the heat treatment cycle on the performance of steels, particularly tool steels. The major reason is improvement in the wear resistance property, which is very critical for the tool steels. A lot of claims for improvement in the property were published. These claims include:

1) Improvement in the wear resistance of carbide tools
2) Stabilization of the dimensions of aluminum parts
3) Extension of life in copper resistance – welding electrodes

But the understanding behind these property changes is still not very clear. Various mechanisms have been proposed but those are not yet accepted universally. These claims include precipitation of eta-carbides, conversion of retained austenite and stabilization of martensite.

There are mainly two kinds of low temperature treatments. A cold treatment, which is carried out at about –176°F, and deep cryogenic treatment that is carried out at –385°C (liquid nitrogen)

Cryogenic treatment we can say is an extension of the quenching process. Increase in the carbon content and alloy content leads to decrease in Ms Temperature and so the Mf temperature, which is generally below the room temperature for tool steels. By performing the low temperature heat treatment the transformation is completed and better stability in the properties are developed.

It is claimed that the advantage of using deep cryogenics is due to an enhancement of the precipitation of fine eta-carbides during the subsequent temper. The strain energy in the martensite lattice increases at a lower temperature. As a consequence Carbon atoms migrate and form clusters. During the subsequent heating back to the room temperature or even a tempering, these clusters act as nuclei for the formation of the ultra fine eta-carbides. Thus the steel product that results boasts improved hardness, toughness, wear resistance and resistance to fatigue cracking

The effectiveness of the cryogenic treatment at liquid nitrogen temperature was found to depend on
• The number of tempering cycles performed prior to freezing
• The use of either a high or low tempering temperature prior to freezing
• Use of tempering cycles after freezing as an extended quench

It was also claimed that as a result of cryo treatment there is an enhancement in the surface compressive stress

Source:http://tptc.iit.edu/members/Reports/2001-12/TPTC%20REPORT%20DEC%202001_Rajendra.pdf

Cryogenics goes Deeper

Although the application of deep cryogenics to cutting tools has yielded widely variable results in the past, current data from laboratory and field tests indicate that treatment can markedly increase tool life.

In spite of recent studies showing that deep cryogenics can improve the performance of cutting tools, the use of freezing processes to treat alloy-steel tools is debated in the metalworking community. In the 1950s and 1960s, when cryogenic treatment involved the direct immersion of tools in a medium maintained at -320° F, thermal shock typically damaged the tools. Memories of the unpredictable results of this earlier process have discouraged further R&D and use of cryogenic treatment.

As currently practiced, deep cryogenics does not directly expose cutting tools to cryogenic fluids. To minimize thermal shock, the tools are placed in an airtight refrigeration chamber (cold box) and the temperature of the tools is reduced gradually. The tools are then soaked in a dry cryogenic atmosphere at -310° F to -320° F for 20 to 60 hours, after which they are slowly returned to room temperature and subsequently tempered. The exact temperatures and times vary from manufacturer to manufacturer. Because this process is so time-consuming, it must be applied after heat-treatment. Without knowledge of the tools' heat-treat characteristics, the results of cryogenic treatment are completely unpredictable.

Comaprison of drilling thrust force for cryogenically and untreated twist drills when machining 4340 steel.

Drilling conditions and improvement results for laboratory test comparing cryogenically treated and untreated tools.

Source: http://www.ctemag.com/dynamic.articles.php?id=60

The Effects of Cryogenic Treatment on the Thermal Conductivity of GRCop-84

The mechanical properties of many materials have been enhanced via cryogenic treatment, which is a cold temperature process performed after traditional heat treatment. In this research the effect of cryogenic treatment on GRCop-84 was examined. Cryogenically and non-cryogenically treated samples were tested identically to determine whether cryogenic treatment has a significant affect on the thermal conductivity of GRCop-84. Optical and electron microscopy were used to characterize the material properties. Cryogenic treatment includes a temper that appears to be responsible for the enhancements observed in GRCop-84.

Cryogenic treatment is a cold temperature process performed after traditional heat treatment, not a substitute for proper heat treatment. Cryogenic treatment has been shown to enhance mechanical properties in many materials. The effect of cryogenic treatment on the thermal conductivity of a copper alloy developed by NASA (GRCop-84) was tested. Potential applications of GRCop-84 include regeneratively cooled rocket engine liners.
Source:http://web.ebscohost.com/ehost/pdf?vid=1&hid=104&sid=8f79dbbe-f760-4574-90f7-3e443e7cbffc%40sessionmgr104

Cryogenic treatment of production components in High-wear rate wells

"Deep Cryogenic Tempering (DCT) is a specialized processwhereby the molecular structure of a material is “re-trained” through cooling to –300º F and then heating to +175-1100º F. Three Shannon Formation wells were selected (TD about 500 ft) based on their proclivity for high component wear rates.

Phase 1 of the test involved operation for a nominal 120 calendar day period with standard, non-treated components. In Phase 2, treated components were installed andoperated for another nominal 120 calendar day period. Different cryogenic treatmentprofiles were used for components in each well. Rod pumps (two treated and oneuntreated) were not changed between test phases. One well was operated in pumped-offcondition, resulting in abnormal wear and disqualification from the test. Testing showsthat cryogenic treatment reduced wear of rods, couplers, and pump barrels. Testing ofproduction tubing produced mixed results."

Source: http://www.osti.gov/bridge/servlets/purl/794381-1aya1J/native/794381.pdf

Deep-Cryogenic Treatment of Steel

The deep cryogenic tempering process for gears is an inexpensive, one time, permanent treatment, affecting the entire part, not just the surface. Gears may be new or used, sharp or dull, and re-shaping will not destroy the treatment.

The process of deep cryogenic or freeze tempering is really quite simple. “A freeze tempering process means that the material to be treated is not exposed to any liquid nitrogen, which eliminates the risk of thermal shock. The material is frozen through a thermo dynamic refrigeration cycle. The material is cooled slowly, held for a prolonged period of time 48-60 hours, and allowed to return to room temperature slowly.”

Source: http://coldfire.com.au/uploads/Deep_Cryo_Article-Ferland.pdf

Frozen Gears

Durability is the most important criterion used to define the quality of a gear. The freezing of metals has been acknowledged for almost thirty years as an effective method for increasing durability or wear life, and decreasing residual stress in tools steels. The recent field of deep cryogenic (below-300°F) has brought high super conductors, the superconducting super collider, cryo-biology, and magneto hydrodynamic drive systems. It has also brought many additional durability benefits to metals.

Source:http://www.cryoeng.com/images/Frozen%20Gears.pdf

Cutting Tools Engineering

Although its effects on metal composition are subtle, deep cryogenic tempering can yield dramaticimprovements in tool performance.

In the search for cutting tool engineering that can increase productivity, prolong cutting life, and decrease costs, gains of 15% to 20% are considered significant. One recently developed tool treatment is showing far greater promise, in some cases improving tool life by 200% to 400%.

The method, called deep cryogenic tempering, subjects tools placed in a specially constructed tank to temperatures below -300 ° F for a number of hours using liquid nitrogen as the refrigerant. The process supplements standard heat/quench tempering, completing metallurgical changes that heat treatingbegins.

Source: http://www.cryosciencetechnologies.com/documents/cutting_tool_engineering.pdf

Controlled Dry Cryogenic Process

What is a controlled dry cryogenic process?
Cryogenics, a product of aerospace research, refers to temperatures below (-280°F). A dry process means that material to be treated is not exposed to any cryogenic liquids, which eliminates the risk of thermal shock. The material is frozen through a thermo-dynamic refrigeration cycle. Controlled simply states that the entire process is performed according to a precise, prescribed time table. The material is cooled slowly, held for prolonged period of time, 20-60 hours, and allowed to return to room temperature slowly.

The treated material maintains its original size and shape throughout the cryogenic process. Although a material is stronger at lower temperatures, following treatment, they show no change in yield of tensile strength. The treated material does become less brittle but without losing hardness. What does change most significantly and considerably is an increase in the material's toughness, stability and wear resistivity.

In contrast to various other surface treatments, the dry cryogenic treatment is a one time only process and affects the material through and through. Re-sharpening or redressing of worn tools does not destroy the effects of the treatment. Tools may be new or used, sharp or dull.

Source: http://www.300below.com/press/magazine-articles/the-promise-of-cryo.html

Advancement of Cryogenic Science

All Aluminum and aluminum alloy castings have built-in stress due to the shrinkage of the molten metal after it cools in the molds. Some of these stresses can be reduced and in some areas eliminate by good casting design, by the foundry properly incorporating stress risers.

Castings that have to be machined for closer tolerances, flatness and better surface finishes will, in most cases, distort on these surfaces, which in turn affects the tolerances and flatness of the critical areas. This distortion starts when the outer layer is removed by machining.... this outer layer locks in the stresses and when removed, the machined surfaces will de distorted.

What can be done to relive these stresses before machining?
Through the advancement of cryogenic science, it has been discovered and proven that when these castings are treated in a cryogenic chamber at temperatures of 88°F Kelvin (-300°F) at a controlled time/temperature cycle, all internal stresses are relived. These components will now retain a flatness/parallelism here-to-fore not possible.

They will maintain a dimensional stability in their use function far above the non-treated part. This is due to the re-alignment of molecular structure that has been distorted during the casting or heat treating process. When these cryogenically treated castings are machined, there us no distortion on the machined surfaces… if there is a distortion, it is caused by improper machining, dull cutting tools, speeds and feeds being too slow and /or not enough material removed at the first cut.

Source: http://www.300below.com/press/magazine-articles/controlled-dry-cryogenic-process.html

Effects of cryogenic treatment and refrigerated air on tool wear when machining medium density fiberboard

Cooling of cutting tools with liquid coolants and lubricants is impractical when machining dry wood or wood composites. This study examines the combined effect of cryogenic tool treatment and using refrigerated air for cooling tools on reducing tool wear. A total of four, double-flute, solid, tungsten carbide router bits were used to machine medium density fiberboard with a CNC router.

Source: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGJ-4VNH3V5-7&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f65e1dbb7aeab394ff4a6af08bf74a69

New approach of cryogenically treating tools -Purdue University researcher

According to Robert Gazo, Purdue University researcher has discovered a way to save energy and money by cryogenically freezing tools for 24 hrs before use. Gazo along with other researchers has tried approaches to cool the tools, which include blowing refrigerated air onto the tools and cryogenically freezing the tools, as well as a combination of both. Professor Robert Gazo and other researcher tem has concluded that freezing tools for 24 hours before use allowed them to stay sharp longer, reduce repair and replacement costs.

According to John Koucky, president of 300 Below, Inc, the process changes the microstructure of the tools by lowering the temperature to 300 degrees below zero, then bringing back to ambient temperature.

Source: http://www.purdueexponent.org/index.php/module/Section/section_id/11?module=article&story_id=17068

Cryogenic motorsports engine treatment

Cryogenic treatment of both new engine and used engine by metal exposed to extreme cold temperatures. Engine is stripped down completely and indvidual components are treated through use of Nitrogen, this process allows enough gas into the chamber to cool the load to the desired point on the cooling profile.

Source: http://www.cartuningtips.com/105-cryogenic-engine-treatments

Cryotech treatment saves money and time

Cryotech process is proven as an effective treatment for tools, musical instruments, golf clubs, auto parts and other steel parts. The cryotech process has increased the results of wear resistance without diminishing hardness. In cryotech model fine carbide particle is not added to the microstructure of steel during process and resulting in greater tensile strength.

Source: http://www.300below.com/press/magazine-articles/job-shop-technology.html

Deep Cryogenic treatment for racing parts

For the motor sports racers it is the ultimate competitive advantage. Deep cryogenic treatment refines the microstructure of the metal in racing parts and enhances the metal durability.

Cryogenic treatment through dry, inert vapors of LN2 temperature of racing parts below 300° F, helps in reducing the residual stress of the component.

This process of deep cryogenic treatment is applied to brakes, engine parts, transmission and bearings.

Source: http://www.nitrofreeze.com/2009/01/new-cryogenic-treatment-service-for.html

"Coating" the structure of metals at deep cryogenic temperatures

Durability is the most important criterion when defining the quality of a tool steel. Cryogenic tempering of metals is becoming acknowledged as an effective method for increasing durability, or "wear life", and decreasing residual stress in tool steels. The process creates many benefits for steel, including an exceptional increase in durability and wear resistivity, generally exceeding 300% as the greatest benefit. Tensile strength, an increase in toughness and greater stability through the release of internal stresses are also created.

Deep cryogenics (below -300°F­) is creating new applications in science. High temperature superconductors, the super-conducting super-collider, cryobiology, magnetohydrodynamic drive systems for ships and low-temperature physics have all developed recently.

Source: http://www.300below.com/press/magazine-articles/modern-applications-news-magazine.html

Dry cryogenic processing physically transforms the micro-structure into a new, more refined, uniform substructure, which is stronger.

Deep Cryogenics has enhanced the racing engine parts more durable and even for some instances doubled and tripled their productive life.
Cryogenics temperature occurs abovemolecules change and make all the retained austenite turn to martensite. Dry cryogenic must physically transforms the micro structure into a more refined, uniform substructure.

Source:http://www.300below.com/press/magazine-articles/short-track.html

Cryobiological Inventory Systems

Store samples up to 225 days without replenishing liquid nitrogen

• Compact size stores up to 3600 samples
• Advanced vacuum insulation minimizes liquid nitrogen evaporation

Find the sample you need quickly and efficiently! All Locator systems feature a double-walled, vacuum insulated vessel with a narrow-mouth neck that keeps liquid nitrogen losses to a minimum. Stainless steel racks fit snugly against the wall of the Locator system to hold multiple racks. The rack handles rest in numbered slots for easy identification and retrieval. Each rack has individual storage locations for cryogenic boxes.

Source:https://www.coleparmer.com/Catalog/0708_pdf/K_0411.pdf

Deep Cryogenic treatment of gun barrles and benefits

Guns created from forging and castings cooled at different rates, induce residual stress. Gun barrel are bored and machned which causes stress in the microstructure of the metal. But cryogenically treat gun barrel below -300°F relives the residual stresses.

Source:http://armsvault.blogspot.com/2008/05/cryogenic-treatment-of-gun-barrels.html

Cryoplus LN2 Microprocessor

The CryoPlus Series LN2 Storage system stores samples below -266°F (glass transition) for long-term preservation of viability. LN2 micro processor controls allow precise and accurate control over all 16 parameters without complicated programming.
Source:http://dansteadtraveller.com/?p=990

Cryogenic treatment can be done on tools coated with TiN, TiCN, TiAIN, and TiAICN

The Cryogenic Institute of New England offers custom based cryogenic treatment for tools used in manufacturing industry

Even though coatings such as TiN, TiCN, TiAIN, and TiAICN are already widely used and relatively inexpensive; cryogenic treatment should be kept in mind. Cryogenic treatment can used on tools that have already been coated without causing any problems. Coatings will help keep the tooling sharp and increase wear resistance as will cryogenic treatment.

Source:http://www.cnczone.com/modules.php?name=News&file=showarticle&threadid=82275

Deep Cryogenics processing significantly increases rifle accuracy by relieving residual metal stresses in the barrel

The deep cryogenic process for rifle barrels controlled with dry thermal treatment. The material is cooled up to -310°F held for a day then raised to +310°F and slowly returned to room temperature. The dry thermal process prevents rifle barrel from thermal shock.
Source: http://www.300below.com/press/magazine-articles/swat.html

Deep Cryogenics makes engine parts more durable

Many racers have tried this method by applying with dry ice to heat treatment approximately -120°F to change molecular structure of metal..

It is at cryogenic temperatures (-300°F) that the molecule change, making all the retained austenite turn to marstensite, a more dense, refined mix that is smaller and more uniform than austensite..

Dry cryogenic processing transforms micro-structure into stronger uniform substructure..

Source: http://www.300below.com/press/magazine-articles/short-track.html

Cryo Rotors Brakes

Brake rotor and drums is enhanced with 250% to 400% improvement in brake life using computer-controlled cryogenic temperatures at -300°F.

Source: http://www.300below.com/press/magazine-articles/emergency-fire/rescue--police-product-review.html

Cryogenic processed rotors

Green testing lab has conducted a testing on cryogenically processed rotors of Precision fleet brakes with traditional OE rotors and the result was precision fleet brakes were lasted two and half times longer than the traditional OE rotors.

Source: http://aftermarketbusiness.search-autoparts.com/aftermarketbusiness/Distribution/Cryogenic-rotors-outperform-OE-states-company/ArticleStandard/Article/detail/601301?contextCategoryId=41884