Redevelopment Of DEFORM And Optimization Of Free Forging Of Large Ingot

A research of numerical simulation of hot forging process and microstructure evolution is presented in this paper. The research works,which include software redeveloping,experimental verification and industrial application,are summerized as follows.A thermal rigid-visco-plastic constitutive relation accompanied by dynamic recrystallization is implanted into DEFORM3D based on the UNIX and Windows system by means of the user routines in order to add the function of predicting microstructure evolution during hot forging process to DEFORM3D. Because the limited opening of DEFORM to use some external files for storing historical data of the user variables have to be built,and the interpolation routines have to be also made for transformation of the user variables stored in the external files after remesh. Comparing with other similar study,the advantage of the added function here is that the redeveloped DEFORM3D can not only predict the average grain size,but also analyse the generation and development of the duplex grain during hot forging.An experiment of the scaled down FMV forging process is carried out under the conditions of different high reduction and different speed of upper anvil in order to verify the redeveloped DEFORM3D,the constitutive relation inserted in DEFORM3D and the material constitutive parameters.The numerical simulation of the above experiment process is carried out by the redeveloped DEFORM3D. The influences of the high reduction and the upper anvil speed on microstructure evolution are discussed. A comparison between the simulated and experimental results on distribution of the average grain size shows that both results are in agreement very well. This means that the redeveloped DEFORM3D is successful. This also shows that the constitutive relation implanted into DEFORM3D and the constitutive parameter values used in the numericalsimulation can describe correctly the physical process of dynamic recrystallization and the coupling of the macroscopic deformation and microstructure evolution.The ratio of V-anvil width in the FMV forging method is optimized with numerical simulation according to the principle of larger deformation in the ingot center and smaller load. An optimum ratio of the upper anvil width and the lower anvil width is obtained. The optimum anvil width ratio is 1:1.5.The temperature field of the huge stream turbine rotor during free forging is numerically simulated with different process parameters. The purpose is to find out a set of optimum process parameters so that the temperature of the rotor center does not exceed the limit temperature of abnormal grain growth which is about 1100C. The simulated results are provided as the reference data of process design for eliminating the defect of duplex grain.Zeng Zhipeng (Material processing engineering) Directed by Jin Quanlin...