Optimization of mold design for aluminothermic welding of railway tracks by software simulation

The aluminothermic welding process of rail welding has been used to join railway rails for more than a century. The benefits of this procedure include its flexibility, compactness of the weld, and ease of execution. It is not necessary to bring in outside energy to complete the process. It is provided by the exothermic effect of the chemical reactions of the aluminothermic mixture's constituents. The design of the mold with the pouring system, which should ensure even pouring of thermal steel, without turbulence, then even heat dissipation or cooling in order to obtain appropriate micro and macro structure of steel, without internal and external defects, is an important element for making a welded joint of the required quality. As a result, the mold's design was constantly evolving, requiring the use of costly experimental methods in industrial settings. Today, software packages are used to simulate traditional casting processes that can be used in the casting of thermite steel during the manufacture of welded railway joints, thereby avoiding costly and time-consuming industrial tests. The simulation of casting thermite steel in the mold cavity, i.e. in the weld joint for the 49E1 rail, using the NovaFlow & Solid CV software package, is presented in this paper. The simulation results were validated by establishing test welded joints in industrial settings and testing their quality in accordance with the EU 13740-1: 2017 standard.