The theory of cryogenic hardening refers to the process of treating metals by cooling them to very low temperatures for an extended period of time. The intention is to produce a material that is tougher, stronger and more resistant to wear and tear. There are several synonyms for this process including cryogenic treatment or cryo-treatment, cryogenic tempering or cryo-tempering, and deep cryogenic processing. All these terms refer to the science of achieving better mechanical properties in metals through the use of low temperatures over an extended period of time. This technology has many applications in industries such as aerospace, automotive, and sports.