Papers by Author: Hui Qin Chen

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Authors: Wen Wu He, Jian Sheng Liu, Hui Qin Chen, Hui Guang Guo
Abstract: Hot-compression experiments of 316LN stainless steel have been conducted on a Gleeble-1500D thermal-mechanical simulator. We have analyzed the flow stress-strain curve and acquired the constitutive equation of 316LN steel by calculating stress exponent, activation energy and Zemer-Hollomon parameter. Then, based on the material model theories and Prasad instability criterion, the iso-efficiency map at strain 0.6 of 316LN steel has been developed. The larger power dissipation rate is emerging at 1050~1200°C and lower strain rate. In addition, we have also analyzed the hot deformation microstructure mechanism of 316LN steel is discontinuous dynamic recrystallization by the observation of deformation microstructure. These results have been of great significance to understand microstructure evolution and to determine the optimum hot-working conditions in the production.
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Authors: Ji Hong Tian, Jian Sheng Liu, Hui Guang Guo, Hui Qin Chen
Abstract: In order to solve the problems such as cracking, uneven property and poor forming controllability in the traditional hot forging of Mn18Cr18N retaining ring, a new intramode canning hot forging process was developed. In this paper, the hot deformation behavior of the material was invstigated by thermo-mechanical molding tests. Based on the results of the tests, the new process was studied in detail and the main parameters were optimized by means of numerical simulation method. The experiment shows that the process was reasonable for forging Mn18Cr18N retaining ring.
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Authors: Wen Wu He, Jian Sheng Liu, Hui Qin Chen, Hui Guang Guo
Abstract: In order to investigate microstructure evolution of Mn18Cr18N retaining ring during the multi-fire forging, a series of constitutive equations for dynamic recrystallization, static recrystallization, meta-dynamic recrystallization and grain growth were developed and implemented into a Deform FE simulator. The single-axial hot upsetting test has been performed to investigate the process of microstructure evolution and to show validity and effectiveness of the developed program. Then based on the modified boundary condition, hot forging process for 300MW retaining ring was put into effect. The results have displayed that the microstructure prediction tool was validated by comparing the simulated grain structure with that of the experiment and it could provide a reference to optimize forging processes in the production of retaining ring.
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