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Tham khảo tài liệu 'steel heat treatment - metallurgy and technologies 2nd ed - g. totten (crc_ 2007) episode 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Quenching and Quenching Technology 589 1 2 3 FIGURE 9.52 Quenching chamber for intensive quenching of semiaxes in a pressurized water flow 1 semiaxis 2 quenching chamber 3 water flow 4 mechanical drive for the semiaxis 5 sensor for analyzing the process of film boiling and nucleate boiling 6 sensor for analyzing the portion of formed structures 7 8 amplifiers. and minimal distortion. Furthermore it has been demonstrated that the service life under cyclic loads may be increased by approximately one order of magnitude 54 . Intensive quenching requires appropriate quenching facilities and quenching media. Quenching media include pressurized water streams water containing various additives and liquid nitrogen. Figure 9.52 shows a quenching chamber for the intensive cooling of an automobile semiaxis using pressurized water flow. The water supply to the chamber and the charging and discharging of the axles are controlled by two sensors. The first sensor 5 in Figure 9.52 analyzes the process of film boiling and nucleate boiling and the second 6 describes the transformation of austenite into martensite by the change of the ferromagnetic state of the material. One method of intensive quenching has been used that achieves maximum compressive stresses at the surface when sensor 6 indicates a specific magnetic phase transformation. In this case sensor 5 is used to minimize the duration of film boiling by regulating the water flow velocity. A second method has also been used with sensor 5 indicating the beginning and completion of nucleate boiling while sensor 6 controls the water pressure and determines the end of intensive quenching so that no more than 30 martensite is formed. Intensive quenching methods offer many possibilities for the successful cooling of parts with optimized strength properties and improved service life. However a precondition for the use of this technology is the development of appropriate quenching equipment that enables precise control of the .