Increasing applicability of ultrafine-grained (UFG) materials processed by Severe Plastic Deformation (SPD) methods can be achieved by producing material in a form that can be easily subjected to further processing by, e.g, metal working. A suitable shape of material for such processes is a sheet or plate, therefore SPD methods with such billet geometry are developed. Another issue is that metal working of UFG materials can be challenging as SPD processed materials are known to have very limited ductility [1]. This research addresses those two issues, i.e. SPD method and limited ductility, as is focused on a method designed for producing UFG sheets, which offers a simple way to acquire sheets that are characterized by high formability at elevated temperatures.

The proposed SPD method is hybrid process combining multi-turn Equal Channel Angular Pressing and upset forging. In this research, the formability and ductility, under various strain rates and temperatures, of ultrafine grained plates of commercial 5754 aluminium alloy are discussed. The plates mechanical properties at elevated temperature and selected strain rates are analyzed and it is indicated that by proper selection of deformation parameters it is possible to achieve elongations exceeding 80% without substantial grain growth. Additionally, formability of plates is tested using cupping test and a two-fold increase is observed, expressed as an increase in the cup height value in a cupping test of a UFG sheet compared with room temperature. This formability enhancement is compared to coarse grained 5754 sheets deformed at room and elevated temperature, as shown in Fig. 1, which shows that greater enhancement of formability is achieved for UFG plate.

Substantial increase of formability and ductility of UFG alloy is attributed to enhanced strain rate sensitivity indicating a change in the deformation mechanisms at work, i.e. the nucleation and propagation of dislocations through grain and diffusion processes.