.300 Mw Retaining Ring Mandrel Reaming Process Optimization Testing And Simulation Studies

Nowadays the large size retaining rings more than 300MW are always produced by the steel retaining ring Mn18Cr18N. Since the producing process applies the traditional techniques, it is easy to cause the problems of cracking, uneven organizational performance, and poor control in the free forging. Currently, though an organizational model can be completely built in research on the microstructure, there has not been a breakthrough in the application. Remaining at the experience control stage, mandrel reaming process in retaining rings lacks the guidance in the formulation of parameters. Therefore it is important to study the application of microstructure models and the control of grain size in the forging process.With the method of combining the physical test simulation and computer simulation and applying the Mn18Cr18N steel microstructure model, this paper conducts the scaled test study of the mandrel reaming process. Meanwhile it optimizes 300MW mandrel reaming process in retaining rings from the aspect of controlling of the forging grain size, providing a basis for the control of grain size in the forging process. Main contents and conclusions are:1. Using test methods, we measure the temperature changes during each measuring point of the Mn18Cr18N steel specimen in the air cooling, use DEFORM software to simulate the temperature change in the process and calculate the heat transfer coefficient under such conditions between sample and air. We find that thermal diffusion has little effect on the temperature field and when the heat convection coefficient is 0.03N/sec/mm /℃, the test results error is the minimum.2. Focusing on the retaining ring mandrel reaming process in the hot forging, we test and study on the scaled test model simplification. Using metallographic analysis, we measure changes in grain size specimens of steel Mn18Cr18N under different deformations conditions. Then we organize and stimulate the test model with DEFORM software, compare with experimental results and carry out error analysis. Besides some large errors, the other almost errors of the grain size of the measuring point are less than 20%, thus mean the effect of the organized values simulation is good.3. Aiming at controlling the grain size, we optimize and analyze the laps, total reduction rate, mandrel size and other parameters in the retaining ring mandrel reaming process in the hot forging of 300MW and simulate and predict the changes in grain size within the retaining ring. The results show the optimal scheme: pressure twice. The every anvil pressure of the first lap is 30mm and the second is 35mm. After first lap pressure is done, turn the mandrel fromΦ360mm toΦ420mm.