Abstract
An existing flow stress model proposed by Barnett was examined with as-cast homogenized AZ31 compression test data for a range of temperatures (250-450oC) and strain rates (0.001-20s-1) from literature to verify the applicability of the model to direct extrusion of AZ31. The model was successful in predicting the hardening region of the flow curve but was unable to simulate the sizable softening component of the flow curve that as-cast homogenized magnesium alloys tend to have before failure. In order to correct this shortcoming, an empirical softening expression was developed with the same range of temperatures and strain rates. This modified flow stress model was then implemented into the finite element software package DEFORMTM 3-D to examine the hot-direct extrusion of hollow AZ31 automobile structural components fabricated using a port-hole die.