We are often told that cryogenic processing is bogus because there is no research to support it.  Here are some quotes from research papers from a variety of sources.  The headlines are ours, the quotes are from the research with minor clarifications where needed.  We've quoted our sources so you can look these up yourself to assure the accuracy and read the papers.   We strongly urge you to read the papers to gain a complete understanding of how these conclusions came about and their precise meaning.

1. 50 % Tooling Cost Reduction

The deep cryogenic treatment (-196 degrees C) of quenched and tempered high speed steel tools improves their properties, in particular, it increases the hardness and improves the hardness homogeneity reduces the tool consumption and the down time for the equipment's set up, thus leading to about 50% cost reduction.   ...While in the AISI M2 steel the increase can be attributed to the increased hardness, in the case of AISI H13 steel the increased wear resistance can be correlated to the increased toughness.
EFFECT OF DEEP CRYOGENIC TREATMENT ON THE MECHANICAL PROPERTIES OF TOOL STEELS, A. Molinan, M. Pellizzari, S. Gialanella, G. Straffelini, K.H. Stiasny.  Journal of Materials Technology 118 (2001), Pages 350-355.  The above named researchers are with University of Trento, Trento Italy, and/or GKN Birfield AG.  GKN is a world wide manufacturer of automotive drive line parts for OEM and replacement markets.

2. Martensite Changed by Cryo

Our recent research results have proved that the martensite formed in prior heat treatment is further changed during the cryogenic treatment.
"Cryogenic Treatment: The History, The Hype, and The Science", Yuntian Theodore Zhu, Los Alamos National Laboratory, Lecture at Illinois Institute of Technology, June 4, 2001

3.  Reduced Residual Stress in Aluminum

 The following results were observed for this particular Al(aluminum) alloy after cryogenic treatment:

       1.  Residual Stress was reduced by up to 12 ksi in the HAZ of weld specimens and by up to 9 ksi in    the parent metal.
       2.  Significant improvements in SCC  (stress corrosion cracking) performance were seen for weld specimens.
       3. Minor increases in tensile strength and hardness were noted for the parent metal.
EFFETCS OF CRYOGENIC TREATMENT ON THE RESIDUAL STRESS AND MECHANICAL PROPERTIES OF AN AEROSPACE ALUMINUM ALLOY, Po Chen, Tina Malone, Robert Bond, Pablo Torres: NASA and IIT Research Institute, George C. Marschall Space Flight Center.

4. Increased Fine Carbides, Increase Wear Resistance, Increased Toughness

The effects of this deep cryogenic treatment mechanism are:
A much greater number of fine carbide particals in the microstructure.
A different partition of alloying elements between matrix and carbides, compared with conventionally treated steels.
An improvement in wear resistance of the steel.
An increase in toughness
Little or no increase in hardness. 
CRYOGENIC TREATMENT OF TOOL STEELS, David N. Collins, National Heat Treatment Centre, University College, Dublin Ireland; Advanced Materials & Processes, December 1998, H23 to H29.

5.  Micro Cracks Eliminated, Carbides Modified

        1. There is distinctive change in the microstructure of AISI T42 High speed steel during Deep Subzero treatment.
             2. The change takes place during the warming up of the steel between 8 and 16 hrs of DSZ
             3. There is change in the morphology of carbides. This change contributes towards ‘rounding off’ of the irregularly shaped carbides at corners and edges in to regular round shape.
             4. The phenomenon of merging / migration / dissolution of finer globular carbides takes place during the process leading to uniform distribution in the matrix.
             5. The micro cracks present due to earlier processing are eliminated completely in the process.
             6. The stress generated dislocations at the interface of the particles and the matrix causes diffusion, which is driven by the concentration gradient.
             7. The soaking time more than 8 and 16 hrs leads excessive contraction of the matrix thereby preventing any diffusion phenomenon.
             8. With the aforesaid changes taking place during the DSZ process, there is improvement in the tool life, which has been experienced by number of researchers.
DEEP SUB ZERO PROCESSING OF METALS AND ALLOYS – PART II  EVOLUTION OF MICROSTRUCTURE OF AISI T42 TOOL STEEL, C.L.Gogte1   , Kumar M. Iyer 2,    R.K.Paretkar1,  D.R.Peshwe1
1. Department of Metallurgical and Materials Engineering, VNIT, Nagpur, Maharashtra, India.
2. Assab Sripad Steels Ltd., Chennai, India

6.  Modification of Carbide Population

In summary, cryogenic treatment cannot only facilitate the carbide formation and increase the carbide population and volume fraction in the matensite matrix, but can also make the carbide distribution more homogeneous.  Our results are consistent with previous studies that show increases in carbide density and volume fraction, which may be responsible for the improvement in wear resistance.
Microstructure of cryogenic treated M2 tool steel.     J. Y. Huang, Y. T. Zhu, X. Z. Liao, I. J. Beyerlein, M. A. Bourke,  T. E. Mitchell: Materials Science and Technlogy Division, Los Alamos National Laboratory, MS G 755, Los Alamos, NM 87545.  Publishe in Materials Science and Engineering A339 (2003) pages 241-244

7. Copper Welding Electrodes Last Longer

Cryogenic treatment of copper welding resistance electrodes increases their life by a factor 2 to 9 . Both durability and conductivity were increased although the mechanisms behind the improvement are being further researched. Metallurgists suspect that stress relaxation through recrystallization is responsible for the property improvement.
Sub-zero Treatment of Steels Technology/Processes/Equipment, Linde AG | Linde Gas Division | 82049 Höllriegelskreuth | Germany

 

8. Cryogenic Treatment and Combination of Nitriding and Cryogenic Treatment of Hot Forging Tools

Conclusions
1. Cryogenic treatment is a process which, compared to steel being quenched and tempered, significantly increases the wear resistance of hot work alloy tool steel. This is confirmed by tribologic tests carried out at elevated temperatures. The achieved growth of the wear resistance depends on the steel grade and on the soaking time of the processed part at the temperature close to that of liquid nitrogen.

2. Due to dilatometric and differential thermal analyses it was possible to state that the reason for a tool steel wear resistance growth are precipitation phenomena taking place during tempering following cryogenic treatment, as at this processing stage a significant amount of very fine and uniformly distributed carbides precipitates; carbides which during work of a tool spall with more difficulty and increase its friction wear resistance under overloads.

3. The phenomenon of significant growth of both the surface hardness and of the depth of internal nitriding and of the hardness measured on the cross-section of nitrated layers achieved for tool steel, which has been subject before to long-term cryogenic treatment, was observed.

4. Comparative research under production conditions of forging dies subjected to toughening and cryogenic treatment and to the combined process of nitriding and cryogenic treatment have demonstrated a wear resistance growth by 20 to 40% as compared to the heat treatment of dies so far applied by manufacturers.

5. In order to better understand the structural transformation taking place inside the internal nitriding zone, the problem of the hardness growth of nitrided layers achieved by combining this treatment with cryogenic treatment must be further researched into.

Cryogenic Treatment and Combination of Nitriding and Cryogenic Treatment of Hot Forging Tools, ZBIGNIEW ŁATAŚ, ALEKSANDER CISKI, Heat Treatment Centre, Institute of Precision Mechanics
Duchnicka 3 Str., 01-796 Warsaw, POLAND;PAVEL ŠUCHMANN COMTES FHT s.r.o. Lobezska E981, 326 00 Plzen CZECH REPUBLIC, psuchmann@comtesfht.cz http://www.coc@imp.edu.pl
Proceedings of the 4th WSEAS Int. Conf. on HEAT TRANSFER, THERMAL ENGINEERING and ENVIRONMENT, Elounda, Greece, August 21-23, 2006 (pp133-139)

9. Cryogenic processing of thin metal films