Study of void closure in hot radial forging process using 3D nonlinear finite element analysis

Hot radial forging is used to reduce porosity and increase strength for large-diameter billets. The goal of this research is to study void closure behavior in the hot radial forging process. A nonlinear coupled finite element model is developed to investigate the deformation mechanism of internal void defects during the hot radial forging process. The model is formulated in a three-dimensional frame and a viscoplastic material model has been used to describe the material behavior subjected to large deformation and high temperature. A global–local technique is employed to obtain accurate solutions around the void region. The effects of void location, mandrel, die shape, and the reduction of the tube thickness on the final void reduction are systematically investigated. The predicted reductions for central longitudinal voids in hot upsetting and hot rolling processes are in good agreement with experimental findings. The simulation results provide a valuable procedure for the design of porosity reduction during the hot radial forging process.