What is cryogenic treatment?

Cryogenic treatment is the process of using extreme cold temperatures to mechanically strengthen a material. One of the newest processes available to automotive enthusiasts, it generally appears to fall into the category of a magic product.

Unfortunately for those seeking a clear answer, discussions on the Digest have revealed that there may be some benefit to properly done cryogenic treatment in specific limited applications. Specifically, the materials must be high alloy steel. Low carbon steel, iron, aluminum, nylon, natural or synthetic rubber, polymers and plastics apparantly cannot benefit, since the cryogenic process is designed to convert austenite into martensite, and these substances only exist inside steels.

Wayne Kasel-Zuzek, who is by profession a metallurgical engineer, also believes that the cryogenic process may only be applied during manufacture as part of the quenching (cooling) process for steels, and that post-quench cryogenic treatment does nothing. His theory is that if a room-temperature quench does not produce the desired amount of martensite, then a cryogenic quench may achieve the desired (or, at least, a superior) result. He also points out that quenched steels, regardless of manufacture, must be tempered prior to use, since martensite is a desireable intermediate stage but is too brittle to be used as a finished product. Once the steel is tempered, he believes there is little that the cryogenic process can accomplish.

Here is a good starting point for reading up on Cryogenics