Finite-element modeling of multi-pass forging of nickel-base alloys using a multi-mesh method

Nickel-base alloys are mostly used for high-temperature applications, many of which are heavily loaded safety components. The material properties highly depend on the microstructure, which, in turn, depends on the metal forming process and the heat treatment. FEM integrated microstructure models can satisfactorily describe the grain size development due to dynamic and static recrystallisation during a metal forming processes and the heat treatment. The simulation results obtained from modeled compression experiments are very promising so that consequently, simulations of more sophisticated processes, like multi-pass open die forging or radial forging, is the next reasonable goal. However, the computation times for the simulation of these processes are still unsatisfactorily Iona and thus, their application is deterred. To accelerate the simulations, a multi-mesh algorithm was implemented to the Finite-Element simulation package PEP & LARSTRAN/SHAPE. This method uses a Finite-Element mesh that is fine in the deformation zone and coarse in the remaining areas of the workpiece. Due to the movement of the tools during the simulation, the deformation zone moves across the workpiece and thus, necessitates a remeshing with a transition of the finely meshed area. A second mesh, which is fine over the entire volume of the workpiece, is used to store the nodal data and simulation results, which get transferred to the simulation mesh every time a remeshing operation becomes necessary. In combination with an adopted data transfer algorithm, this second mesh is used to minimize the loss of accuracy, if a previously finely meshed area becomes a coarsely meshed area. This simulation model can be used to optimize forging process chains with respect to grain size distribution as well as cost effectiveness and energy consumption.