Study On Numerical Simulation Of Metal Flow And Microstructure Evolution Of A Crankshaft Forging Process

As the important component in engine, there is a very high demand on the performance of strength and organization. However, the forging productions of crankshaft often suffer sufficient dissatisfaction, cracks, folds, deformation, pits and other defects. Even if the shape of productions is complete, they may also appear magnetic marks during the magnetic particle inspection. Therefore, to grasp the laws of the metal flow and microstructure evolution in the crankshaft forging process is particularly important. This paper choosed the29D crankshaft that produced by Tianrun Crankshaft Co., Ltd. to do some numerical simulation research. In order to investigate the possible crankshaft forging defects and the causes of magnetic marks, coupled numerical simulation including metal flow and microstructure evolution of the crankshaft forging process was done.In contrast the different numerical simulation methods of microstructure evolution of the metal thermoplastic forming process, the finite element method combined with microstructure evolution model was choosed as a technical means. The microstructure evolution module of existing finite element software was still not perfect, and the applicability to the microstructure evolution model was very poor. So Deform software was choosed as the secondary development platform to build the program. The average alternative method was proposed to simulate the dynamic recrystallization process. This method simplified the data processing procedure. And the problems of macro-micro coupling, parameter updating, parameter clearing were solved.Deform-2D was used to simulate the cylinder upsetting process and the rear axle flange forging process, and the microstructure evolution law was analysised. The simulation results were compared with related literatures and they indicated the program was reliable. Based on these, the program was ported to DEFORM-3D and it was changed to suit for the other type of grids, such as the hexahedral.Macro-micro coupled model of the29D crankshaft forging process was built and it was simulated with the microstructure evolution program. The law of the metal flow, stress field, strain field, temperature field and microstructure evolution were analysised. During the modeling, in order to avoid the adverse effects caused by the poor quality of grid, HyperMesh was used as the meshing tool, the quality and aesthetics of the grid were greatly improved. Based on the simulation results, the metal flow law of pre-forging and final forging process was revealed, the possible forging defects of29D crankshaft and the causes of the magnetic marks were predicted. This paper provided the technical support to optimize forging process and die structure, to reduce forging defects and to eliminate the magnetic marks.