Modeling of a combined process for the production of contact wires for high-speed railways

Abstract

The development of high-speed railways (HSR) is an important task aimed at improving the transport system of today’s global community. The most heavily-loaded element of HSR, governing their reliability and lifetime, is a contact wire. In this connection, the present study was focused on designing a new set of physico-mechanical properties of a wire made from the heat-treatable Cu-0.65Cr alloy with the use of a new procedure of continuous plastic processing, based on the principles of severe plastic deformation. Thus, an important difference from the common technical solutions used in the production of wires was the use of a combination of SPD processes – radial forging and ECAP-Conform, joined with the shape-forming of shaped sections of wire. In our study, we performed finite-element computer and physical modeling of the processes of plastic and heat treatment. Using computer modeling, we demonstrated that as a result of the implementation of the new procedure of continuous processing, a rather homogeneous strained state is formed in the workpiece, and the accumulated strain is in a range of e = 6-7. At all stages of plastic processing, compressive stresses prevail in the deformation site. As a result of physical modeling, we produced laboratory samples of contact wire from the heat-treatable Cu-0.65Cr alloy with a cross-section area of 150 mm2. Metallographic studies reveal that a banded structure of a grain-subgrain type with a fragment size below 1 micron is formed in the laboratory samples of contact wire. The ultimate tensile strength of these samples after heat treatment is 550-560 MPa, the electrical conductility is 72-75% IACS, the ductility is 16-20%.