Since the 1920s and 1930s, with the rapid development of material science, the principle and technology of heat treatment are becoming more and more mature. It is difficult to improve the strength and toughness of metal by conventional heat treatment process, but in many cases, the strength and initial properties of existing materials, especially the corrosion resistance, are not ideal. The proposal of metal cryogenic technology makes people see a unique heat treatment method to improve metal strength and toughness.
What is cryogenic treatment (SSZ)
The so-called cold treatment is generally defined as ordinary cold treatment at 0-100 ℃ and cryogenic treatment below – 130 ℃. It is one of the latest strengthening and toughening treatment processes. According to the process, cryogenic treatment can be divided into deep cooling and rapid heating method and cold and hot cycle method. The cold and hot cycle stabilization treatment is to cool the parts to – 40 ℃ ~ – 90 ℃ or lower temperature for a certain period of time, and then heat the parts to a certain temperature (usually 80 ℃ – 190 ℃) which will not reduce the mechanical properties of the parts, and then heat the parts for a period of time and repeat the cycle process for many times.
“Cold treatment and rapid heating method” is to quench the tool and die, not immediately cold treatment, first water bath and then placed in the treatment tank at – 80 ℃ or – 180 ℃. That is – 80 ℃ for ordinary cold treatment and – 180 ℃ for cryogenic treatment, holding time is calculated as 1 hour per inch volume. After heat preservation, take it out and put it into hot water for quick heating.
In the United States, the former Soviet Union, Japan and other countries, the cryogenic technology is not only applied to high-speed steel, bearing steel, die steel, to improve the wear resistance and strength and toughness of materials, and then to improve the overall service life of the workpiece. At the same time, cryogenic technology is used to modify aluminum alloy, copper alloy, cemented carbide, plastic, glass, etc. It can improve the uniformity, stabilize the size, small deformation and prolong the service life.