Customer Cost Reduction through Cryogenic Treatment The Cryogenic processing of metals and plastics is carried out with an aim to increase the performance of the materials. As part of the treatment, the material is slowly cooled from room temperature down to 196°C in a prescribed time, temperature profile. Once the temperature of –196°C is reached, the materials are soaked at this temperature for a period of 24-72 hours depending on the material being treated. On completion of the soaking period, the temperature is slowly elevated back to room temperature again as per the prescribed profile. This cryogenic processing step causes irreversible changes in the microstructure of the materials, which significantly improve the performance of the materials. The treatment calls for a precise temperature control during the processing, usually up to one-tenth of one degree, necessitating elaborate controls and sophisticated instrumentation.
Advantages of cryogenic treatment It has been observed that the process provides the materials a stronger, denser and more-coherent structure thus increasing the abrasive resistance and thermal and electrical conductivity. For steels, the explanation of the phenomena in Layman’s terms is as follows: Super cooling the steel refines the carbides in the steel by expanding the carbide structure to fill any voids in the metal. Then as the higher temperatures return, everything relaxes into where it wants to be thus providing stability to the steel. Every step in the treatment is carefully controlled else the temperature extremes will shock the steel into delaminating.
Metallurgy of cryogenic processing
Two primary mechanisms are at work in cryo processing. Firstly, the super-cold treatment converts any retained austenite to marten site and the marten site is tempered as the metal return to room temperature. The martensitic structure resists the plastic deformation mush better than the austenitic structure, because the carbon atoms in the martensitic lattice “lock together” the iron atoms more effectively than in the more open-centered cubic austenite lattice. Tempering the martensite makes it tougher and better able to resist impact than un-tempered martensite. Secondly, cryogenic treatment of high alloy steels, such as tool steel, results in the formation of very small carbide particles dispersed in the martensite structure between the larger carbide particles present in the steel. This strengthening mechanism is analogous to the fact that the concrete made of cement and large rocks is not as strong as concrete made of cement, large rocks and very small rocks, (Coarse sand). The small & hard carbide particles within the martensitic matrix help support the matrix and resist penetration by foreign particles in abrasion wear.
Further explanation to the “Concrete effect” is as follows: Cryogenic treatment of alloy steels causes transformation of retained austenite to martensite. Freshly formed martensite changes its lattice parameters and the c/a ratio approaches that of the original martensite. Etta (h) carbide precipitate in the matrix of freshly formed martensite during the tempering process. This h carbide formation favours a more stable, harder, wear-resistant and tougher material. This strengthens the material without appreciably changing the hardness (macro hardness).
The other major reason for the improvement is stress relief. The densification process leads to an elimination of vacancies in the lattice structure by forcing the material to come to equilibrium at –1960C and lowering the entropy in the material. This lower entropy leads to the establishment of long range order in the material which leads to the minimization of galvanic couples in the material thus improving the corrosion resistance of materials including Stainless Steels.
Besides, there is some amount of grain size refinement and grain boundary realignment occurring in the material. These two aspects lead to a tremendous improvement in the electrical and thermal conductivity of the material thus transporting the heat generated during the operation of the tool away from the source and increasing its life.
Typical applications of the technology range from perishable tools and dies to alloy steel wear parts, gun barrels, machine knives and blades transmission gears, shafts, bearing cams, automobile engine parts, camera parts and microelectronic circuits, guitar strings and other musical horns, copper electrodes and the list goes on. This treatment can be carried out on tools and components which have been provided various coatings to enhance certain material characteristics and the net result is an increase in the performance of the coating over and above the existing coating. This has been found useful in the case of TiN, TiCN, Ti Al N, Hard Chrome, Stellite etc. coatings on various materials to enhance their wear resistance.
Cryogenics at a Glance
Increase productive life of your engineering components by 25-100%
Decrease your perishable tooling consumption by 25% and add to your profits
Increase service life of your tools by 50-200%
25 to 100% improvement
Down Hole Pump Parts
SS tool Steel
Sour Oil wells
Low Carbide 484 RC 56Steel
2 to 1
A2 RC 60-62
2 to 1
2 to 1
4 to 1
4 to 1
M2 & M7
3 to 1
M2 & M7
M2 & M7
6 to 1
3 to 1
2 to 1
HSS & Carbides
5 to 1
15 to 1
2 to 1
2.5 to 1
10 to 1
Reduced by 60%
Thin Wall aluminum
50% Saving in time.
What happens in Cryogenics?
Cryogenic processing tinkers with materials at the molecular level at Cryogenic stillness resulting in
Homogenizes the Crystal Structure (Achieved by specially designed advanced ramp-soak time programs)
Grain Structure refinement (New ultra fine carbide particles are formed which are uniformly dispersed throughout the material matrix.)
Improved structural compactness (Copper Alloys, Steel alloys) significant effects even felt in such finely processed materials like piano strings, banjo, guitar strings etc. this shows that material characteristics are different even at such small cross-sections which are easily corrected by Cryo-tech) improves high frequency capabilities. Copper electrodes exhibit improvements in
Prevents concentrated Heat Built-up (Tools, Carbide tools, ball and roller bearings and tools, turbine blades, combustion, chamber, steel industry automobile industry etc. significantly benefit from this improvement)
Increases Resistance to Deformation (Copper electrodes exhibit improvements in service life)
Reduces Deformation significantly (Results in less removal of material for redressing, normal saving in Cryo treated material is between 3 & 5 times)
Reained austenite is converted to a fine martensite matrix (Powdered metal parts, steel alloys etc.)
Mechanical Properties like micro-hardness, Tensile Strength etc. are the same across any crosS-section (Unlike other processes, cryogenic processing is a one time process and its effect is through and through)
Significant improvement in dimensional stability (Helps machineability, very close tolerances obtained, reduced scrap-prior to machining cryogenic processing is carried out in several applications such as in machining of radar domes, cockpit instrument panels, missile parts, special precision bearings etc.)
Relieves residual Stresses (Cutting tools, punches, dies electrodes, castings, forging, automobile gears, cam shafts, crank shafts, ball and roller bearings, springs, cutters, slitters, slotters, trim knives.)
Several fold improvement in hot hardness (Turbine blades, ball and roller bearings even in battle tanks, gun barrel, tools, dies, valves, steel industry, combustion chamber, fluidized beds, missile cones, compact disks etc.)
Significant improvement in material toughness (This process can tinker with material hardness without affecting impact strength adversely)
Binder Materials like Cobalt Nickel and in some cases additives of tantalum, Tungsten or Titanium are advantageously affected (Carbide inserts, brazed carbide tools etc.)
Big decrease in the amount of catastrophic shattering (Powdered metal parts)
Produces stronger, denser parts for better performance and longer service life
Cryogenics – Areas of ApplicationService Portfolio at a Glance
Steel cuttings tools / Cobalt /Tin / Chrome & Carbide Tools, Like Drills, End mills, Reamers, Broaches, HoGs, Form Tools, Routers, Knives, Piercing Tools, Key Cutters, taps , Extrusion Dies, Hot Die Steels, Progressive Dies, Slitters, Slotters, Trim Knives, Cutters, Lathe Beds, Gears, Rollers, Precision Tools, Jewelry Tools
Chipping BREAKAGE : Cryo-tech process should not alter the hardness of any heat –treated material. If such changes are noted or chipping or breakage is evident it is strongly advisable to temper the product at the last tempering temperature designed after its heat treatment process. If chipping persists, it is a good idea to repeat the tempering cycle. Call our consultants for advice
Tolerance/Machining : It is strongly recommended that the final grinding/honing/finishing of the product is carried out after our cryogenic treatment. The result is far greater wear –resistance, tighter tolerance, superior cutting edge and longer service life. In fact, the Cryo-Tech process will significantly improve the performance of material previously treated by other methods.
Dimensional stability : Dimensional stability and stress relief are additional benefits of the Cryo-tech treatment. The cryogenic process can significantly contribute to complete stress relief of castings, forging, surface hardened components and more.
Downtime savings : The cryogenic process shows that improvements made in strength, stability and resistance to wear can and will reduce the cost of a product by having loner tool life, less scrap, fewer rejections, and above all, less costly down time.
Regrind Savings : Slower and less sever wear of cutting tool is significant with cryogenic treatment and less regrind is needed to renew the cutting edge. It is important to account the number of regrinds to estimate the correct service life.
Typical Uses of Cryogenics :
Increase life of tools, products & Stress relieve metals for tear free drawing.
Produce superior tolerances for steel products, improve surface finish, AND INCREASE service life of forgings and castings.
Reduce machine downtime, increase productivity and reduce scrap rate.
Increase Grinding Intervals
Get the product as close as possible to its absolute design limit.
Help switch to cheaper raw materials if desired.
Apex Knives & Cryogenics
We offer Cryogenic Treatment as an option on a wide range of Industrial Machine Knives, Saws, and Blades for varied Cutting Applications for example :
Shear Blades up to 1.5 meters in length
Plastic Granulating Knives
Top & Bottom Circular Knives for Paper Industry up to 300mm in diameter
High Speed Steel Circular Saws for Tube/Metalworking