Structure and properties of the contact wire obtained by ECAP with forming

Abstract

This paper presents the results of the development of a promising method for manufacturing contact wires for high-speed railways. The developed method is based on the principles of severe plastic deformation and the combination of metal-forming processes. The solution obtained is a combination of equal-channel angular pressing with the forming of a shaped contact wire with a cross-sectional area of 120 mm2 in one tooling. A feature of the work is that with the help of a comprehensive study by the methods of finite element computer modeling and a physical experiment, not only the stress-strain state of the deformation zone was investigated but also an analysis was made of the effect of deformation heating, which plays an important role when working with dispersion-hardened alloys, such as Cu-0.65Cr. It was established that the temperature in the equal-channel angular pressing zone reached 490℃ to 505℃, and during shaping, it rose to 510℃ to 530℃. In the course of a physical experiment, a laboratory sample of a contact wire with a tensile strength of 410 ± 8 MPa and an electrical conductivity of 35 ± 2% IACS was obtained. Post-deformation aging led to an increase in tensile strength up to 540 ± 20 MPa and restoration of electrical conductivity up to 76 ± 2% IACS. Due to the formation of a stripe structure of a grain-subgrain type with recrystallized grains along the boundaries, the plasticity of the contact wire sample reached 20%.