The Process

Cryogenic processing, the deep chilling of materials so that the molecular structure of the metal is brought to "cryogenic stillness" in order to improve wear characteristics and impact resistance, is not a new technology. Today's dry process is computer-controlled, utilizing a prescribed temperature profile and maintained at -300F for a calculated time before gradually returning the parts to room temperature. The dry process ensures parts are not exposed to any cryogenic liquids, thereby eliminating the risk of thermal shock. The custom treatment profile is developed according to the specific size, weight, and configuration of the parts being treated. The processor controls the flow of liquid nitrogen into the chamber where the liquid is vaporized and circulated throughout the chamber. Many materials require a flash temper prior to the deep cryogenic step. Once the temperature reaches -300F the process enters the "soak phase" which maintains this temperature for a prescribed duration to allow for transformation of the material at a microstructural level. The parts then must be tempered to approximately +300F after being subjected to the deep freeze phase. This tempering temperature varies for different materials, and the processing time varies for different material cross sections.

Please read Thermal Processing magazine articlefor more detailed information about the cryogenic process in general.