New wire drawing technology by using the effects of changed strain path (Angular Accumulative Drawin

For many years, in most metal forming applications inhomogeneity of deformation has not been desired as it leads to non-homogeneous microstructure evolution. Since it is also difficult to control, non-uniform property distributions appear in the final product. Recently, however, with the growing interest of Ultrafine-Grained (UFG) and Nanostructured (NC) materials, introduction of deformation inhomogeneity is becoming an important way to help improve weak ductility of UFG structures [1]. Although the potential of this approach has already been recognised, proper control of the properties of final products through controlled deformation inhomogeneity still remains extremely difficult [2,3]. Computer simulation, which can be very effective and significantly minimise the cost of expensive industrial or laboratory trials, is becoming a very helpful tool in this research.

In the present work, the recently developed Accumulative Angular Drawing process (AAD) is presented and discussed with respect to its potential to produce wires with enhanced properties thanks to controlled strain accumulation that leads to local high grain refinement. In this process, a complex strain path is applied and, similarly to the Severe Plastic Deformation processes, large strain accumulation is introduced to refine the microstructure of a drawn wire. The applicability of strain path change in the AAD process allows for the preferred distribution of effective strain in the entire cross-section of the drawn product, which, in turn, introduces microstructure inhomogeneity at the cross-section of the wire. These effects – if properly controlled – enable the achievement of a desirable combination of mechanical properties in the final product. In the present study, analysis of microstructure development and their inhomogeneity was carried out in order to understand the deformation mechanisms and to establish the correlation between deformation, microstructure and mechanical properties observed in various metals and alloys. It was proved that by proper control of the process parameters that it is possible to introduce controlled inhomogeneneity of strain and, by accumulation of deformation energy, to induce grain refinement across the cross-section of the wire. As a result enhanced properties compared to conventional wire drawing processes were obtained.