Prediction of void growth in drawing and extrusion of voided metals

Abstract

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.