Void closure during open die forging of large size martensitic stainless-steel ingots: an experimental-analytical-numerical study

In the present research, void closure during the open die forging process of large size AISI410 martensitic stainless-steel ingots was studied using a combination of analytical modeling, finite element simulations, and experimental validations. The analytical model assumes that the voids during deformation can be represented by initially spherical geometry changing to ellipsoid or cracks before being completely closed. Finite element simulations of the open die forging were conducted using the Forge® NxT 3.1 software to simulate the stresses and strains predicted by the analytical model. Hot forging experiments were conducted on large size cylindrical samples at the center of which spherical voids simulating the presence of porosity, were machined. After hot forging, the closure levels of the voids were compared with those predicted by the model and very good agreement (discrepancy in the range of 7%) was observed. This showed that the model could be confidently used for prediction of the void closure in industrial open die forging processes.