Considering the solidification structure of var ingots in the numerical simulation of the cogging process

The main objective of Vacuum Arc Remelting is to control solidification conditions in order to obtain a columnar dendritic structure throughout the whole ingot. The change in primary dendrites’ growth direction, determined by the pool shape, leads to non-isotropic material properties in terms of plastic flow. As the correct prediction of flow behavior is crucial for the further analysis of forming processes (as for example in the application of damage criteria), this specific feature of remelted material has to be accounted for in the modeling of ingot breakdown. Using Barlat’s formulation for the plastic flow, the structural constitution of alloy 718 VAR ingots could be linked to the alloy’s plastic flow behavior by modeling the inhomogeneity of properties determined by remelting experiments and simulations. Hence, the influence of different remelting process conditions on hot workability could be examined. Compared to the commonly used von Mises approach some differences could be revealed. (AU) © 2010 by The Materials, Metals, & Materials Society. All rights reserved.