Prediction of void growth in drawing and extrusion of voided metals

In this work the growth of micro voids during drawing and extrusion processes through conical and wedge-shaped dies is predicted. The solution uses a modified Shield's analysis for the stress distribution within the die zone together with Gurson-Tvergaard's yield function and its associated flow rule for voided solids. The effects of the process parameters e.g. area reduction, semi-die angle and friction conditions on void growth are investigated. Moreover the influences of the initial void volume fraction, void shape and strain-hardening on void growth are considered. The analysis is used to estimate the density change in multi-pass drawing process. The predicted density change is compared with available experimental data for axisymmetric and plane-strain processes. The predictions which are in good agreement with the experiments may be of value in investigating the occurrence of central bursting in such processes.