Cryogenic technology is to use the cold medium as the cooling medium to continue the cold treatment process of the quenched metal material. It conducts metal processing at temperatures close to -200 degrees or lower, thereby changing the extremely fine structure of metals, plastics, ceramics, etc., and changing the wear-resistant structure of the material. Among them, the use in the aerospace industry is more prominent. After the aerospace parts undergo super, processing and thermal shock, their durability and fatigue resistance will be greatly enhanced. Thereby improving the reliability and life of use. Since the 1980s, cryogenic treatment technology has begun to be promoted to the civilian industry. But it is limited to the "cold immersion" type of rough process. Cryogenic treatment equipment did not appear until the late nineties. In addition to cryogenic treatment, the liquid nitrogen cryogenic box can also perform hot and cold temperature shocks at the same time, which greatly enhances the effect of cryogenic treatment. Cryogenic technology is currently a more effective and economical new process technology to strengthen the performance of metal material workpieces.

Liquid nitrogen cryogenic box

　　The main points of operation are as follows:

　　 1. It should be carried out immediately after the workpiece is quenched to avoid stabilization of retained austenite caused by staying at room temperature. The longer the room temperature residence time, the more severe the stabilization of austenite and the worse the effect.

　　2, the martensite transformation mainly occurs in the continuous cooling process. As in quenching, after the workpiece reaches the temperature of the cryogenic box, the transformation is completed without the need for heat preservation. However, in order to make the cores of all the workpieces reach the temperature during batch loading, the temperature can be kept for 1 to 3 hours according to the situation.

　　 4. It should not be carried out before the workpiece is cooled to room temperature. For workpieces with complex shapes and larger sizes, the processing temperature should be lowered from room temperature with the equipment to prevent the workpiece from cracking.

　　 5. After the liquid nitrogen cryogenic box is over, the workpiece should slowly rise to room temperature in the air. Tempering cannot be performed before room temperature, and it should be tempered in time after reaching room temperature, which can prevent the parts from cracking.