Design of a novel experimental profile for the development of a numerical model for extrusion processing of a magnesium alloy

Magnesium alloys are an important structural material to many global industries. Their high specific physical properties are useful in the design of lightweight engineering systems. In this study, the development of a numerical model for the prediction of high-temperature extrusion of an Mg-Zn-Ce alloy (ZE20) is presented. A novel design of an I-shaped profile for extrusion processing was created as part of this effort. This design was used to produce extrudates with large strain gradients across a single profile. In parallel, new numerical tools were developed to predict the extrusion behaviour of the ZE20 alloy. Finite element simulation of the indirect extrusion laboratory trials was used to calibrate the numerical model. Microstructural measurements of experimental samples through EBSD analysis were compared with simulation calculations, and insights into the relationship between extrusion temperature, strain, and resulting microstructure were gained. A fully recrystallised, bimodally distributed grain microstructure was observed throughout the samples. Proportions of grain refinement within the bimodal distribution were shown to correspond with localised strain gradients for a profile with nearly uniform temperature. Ultimately, extrusion press load calculations using the numerical model were shown to be within 5% of experimental trial values.