Structure and properties of low-carbon steel after twist extrusion

Abstract

The new developing technologies of metal formation, based on simple shear, are known as severe plastic deformation (SPD) technologies. They are actively used for improving the mechanical properties of metals. Even complex systems such as steels have not been adequately investigated for SPD process. However, studies are in progress as is reflected from the publications in the literature. Due to insufficient knowledge of the structural changes, occurring in low-carbon steels during SPD, there is a need for a more detailed consideration by modern methods. This paper discusses the characteristics of the formation of structure and texture of low-carbon steels subjected to warm twist extrusion (TE). A relatively new method, which makes possible a detailed study of the structure of metals, is electron backscattered diffraction (EBSD). EBSD has shown that warm TE increases the structure isotropy, thus leading to significant fragmentation and activation of the mechanisms of dynamic polygonization, recrystallization and grain-boundary sliding. These structural features lead to hardening of the material by 1·5 times, while maintaining a high level of plasticity.