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The research presented in this paper concerns the influence of the rate of plastic deformation generated directly in the processes of severe plastic deformations on the microstructure and properties of three metals: copper, iron and zinc. The equal channel angular pressing (ECAP) method was used, and it was performed at a low plastic deformation rate of ∼ 0.04 s−1 . The high plastic strain rate was obtained using the hydrostatic extrusion (HE) method with the deformation rate at the level of ∼ 170 s−1 . For all three tested materials different characteristic effects were demonstrated at the applied deformation rates. The smallest differences in the mechanical properties were observed in copper, despite the dynamic recrystallization processes that occurred in the HE process. In Armco iron samples, dynamic recovery processes in the range of high plastic deformation rates resulted in lower mechanical properties. The most significant effects were obtained for pure zinc, where, regardless of the method used, the microstructure was clearly transformed into bimodal after the ECAP process, and homogenized and refined after the HE process. After the HE process, the material was transformed from a brittle state to a plastic state and the highest mechanical properties were obtained. [ABSTRACT FROM AUTHOR]

This paper presents the effect of severe plastic deformation obtained using the cold hydrostatic extrusion (HE) method on the mechanical and structural properties of polyamide 6 (PA6). As a result of the plastic strain, a significant increase in ultimate tensile strength and tensile modulus were observed. Tensile strength rose by almost 500%, up to the level of 508 MPa, whereas the tensile modulus rose by about 65%. Flexural modulus increase was also observed to 3230 MPa, i.e., by approx. 160%. As a result of high plastic deformation, the structure of the polyamide 6 changed significantly, as evidenced by its fibrous nature as presented in the results of the scanning electron microscopy inspection (SEM). The surface quality of products investigated was tested using profilometry. [ABSTRACT FROM AUTHOR]

The study was concerned with improving the thermo-plastic treatment of the CuCrZr alloy so as to achieve a better compromise between its electrical conductivity and hardness. The experiments included severe plastic deformation (SPD), such as hydrostatic extrusion (HE), equal channel angular pressing (ECAP), and a combination of these processes, all followed by a precipitation hardening stage (solution treatment before the deformation and post-deformation ageing). The aim was to produce a material with a strongly refined microstructure (which is a factor promoting high hardness and high mechanical strength of the material) with the preservation of its high electrical conductivity. The material obtained had an ultrafinegrained structure ( d 2 = 200 nm) and a high ultimate tensile strength UTS = 630 MPa, values which are much higher than those of the reference commercial material used for the fabrication of the spot-welding electrodes. The optimization of the process parameters also permitted achieving a high electrical conductivity of 78% IACS. The CuCrZr alloy is commonly used as the material for the tips of the spot-welding electrodes, especially in the transportation industry. Therefore, the properties of the material obtained in the present study were verified from the applicative point of view i.e. some standardized spot-welding electrodes were fabricated of it and subjected to lifetime tests. The lifetime of the electrodes made of the material subjected to HE + post-deformation ageing appeared to be more than 6 times as long as that of the reference commercial electrodes. In the material treated by ECAP + HE, the result was much less advantageous which was because of the weaker morphological texture compared to that formed characteristically in the materials treated by HE alone. [ABSTRACT FROM AUTHOR]