Analysis of Copper Welding Parameters during the Manufacture of Tubular Profiles Using Unconventional Extrusion Processes

In recent years, there has been a lack of information in the literature regarding the extrusion and connection of closed profiles from oxygen-free copper in bridge dies. Available studies contain information on the processes of extrusion and connection of profiles from aluminium alloys and various types of steel. However, there is a lack of detailed data on the values of technological parameters for which copper is joined in the extrusion process. Therefore, one of the goals of this work is to fill the gap in the literature regarding the extrusion of oxygen-free copper in bridge dies. In this work, the authors determined the thermo-mechanical conditions at which oxygen-free copper will be joined. This paper describes the effects of charge temperature and hydrostatic pressure in the weld zone of a bridge die on copper bonding in the fabrication of tubular profiles. Physical tests of the welding process under the conditions of upsetting a material consisting of two parts were carried out using the Gleeble 3800 metallurgical process simulator with the PocketJaw module in the standard configuration for SICO (strain-induced crack opening) tests. For the numerical simulations, the commercial computer programme FORGE^®NxT 2.1. using the finite element method (FEM) was used. Based on the analysis of the test results obtained, it was found that complete material bonding during the extrusion process could be achieved for a charge temperature higher than 600 °C and a hydrostatic pressure of 45-65 MPa.