Study On The Computer Simulation Of LP Rotor's Quenching Process

With the rapid development of heavy industry in China, such as the metallurgical industry, the electric power industry and the shipbuilding industry, as important equipment parts, the demand of large forgings'production capacity and technology is increasing higher. Due to their characters of big size and high weight, large forgings'heat treatment process is usually very complex. So, it is quite difficult to find the proper heat treatment process for large forgings to get high performances. The appearance and development of heat treatment simulation technology has provided a good solution for large forgings. It is of great significance in saving resources and improving the workpiece performance effectively.Based on the complete consideration of the relationship of temperature- microstructure-stress in the heat treatment process, the mathematical models are established to calculate the temperature field, the microstructure field and the stress field in LP rotor quenching process. Moreover, the specific heat and the thermal conductivity of different microstructures in 30Cr2Ni4MoV steel for LP rotor at different temperatures have been measured by the differential scanning calorimetry and the laser flash method. The accurate thermo-physical properties obtained in the tests provide important input parameters for the quenching simulation of LP rotor. Finally, the quenching process has been simulated with a FEM software package and a proper quenching process has been found for LP rotor with the diameter of 2826mm. The results are valuable to guide the actual production of LP rotor.In the quenching process simulation, two cooling methods have been studied, with or without air pre-cooling. According to the results, the method with air pre-cooling is better and it has advantages for LP rotor quenching process as follows: (1) decrease the difference between the temperature on the surface and the temperature in the core; (2) deepen the quenching hardening layer and enhance the transformation of bainite in lower temperature zone; (3) increase the cooling rate in the core. Based on the conclusions above, for LP rotor with the diameter of 2826mm, the suggestion of its quenching process is 1.5h air pre-cooling adding 30h water cooling.