Ultra low temperature cold treatment technology adopts single machine cascade refrigeration technology to provide refrigeration equipment. Committed to – 150 ℃ cryogenic box research, development, manufacturing, sales and other fields. Cryogenic technology is the most effective and economic high-tech to improve the performance of metal material workpiece. It is a new environmental protection technology with less power consumption and no environmental pollution. At present, the technology has been widely used in aerospace, shipbuilding, military, manufacturing, automobile, hardware tools, sports equipment and other industries.
When there are more carbon and alloy elements in the steel (except AI and CO), the martensitic transformation termination point will be reduced to below 0 ℃, and there will be more retained austenite in the structure after quenching. In order to transform the retained austenite into martensite, the quenched workpiece can be placed in cryogen or refrigerator for continuous cooling, which is called cold treatment. Ultra low temperature cold treatment is usually used in cutting tools, measuring tools, precision bearings and other parts with high dimensional accuracy requirements to improve the hardness, wear resistance and dimensional stability.
The cold treatment temperature should be selected according to the chemical composition (MF point) of the steel. It should be carried out after quenching to avoid stabilizing retained austenite and affecting the effect of cold treatment. In order to avoid cracks in the process of cold treatment, some workpieces with complex shapes can be tempered once and then cooled again. For some workpieces with higher dimensional stability requirements, such as thread gauges, two cold treatments are often required. The cold treatment must be tempered or aged to eliminate the stress and stabilize the newly formed martensite. When the workpiece is in, only when its core reaches the cold agent temperature (generally 1-2 h). After the workpiece is taken out of the equipment, it is slowly heated to room temperature in air, and then tempered.
Cold treatment technology is a new technology to improve the properties of metal workpiece. The so-called cryogenic treatment is to use industrial refrigerator (- 150 ℃) to continue the cooling process of quenched metal materials to a temperature far lower than the room temperature, so as to further transform the retained austenite after conventional heat treatment, so as to improve the properties of metal materials. After cryogenic treatment, the wear resistance, toughness and dimensional stability of metal workpiece can be obviously improved, and the service life of the workpiece can be increased by times.