The Process of Aluminothermic Surfacing of Rails

The process of aluminothermic surfacing of rails is considered. An important problem is the repair of rail surface defects that have occurred during their operation. Aluminothermic surfacing is a promising repair method. Calculations of temperature conditions in the depositing metal–rail system are performed. Important characteristics are determined for various temperatures of the depositing metal, namely the depth of melting of the rail head surface, the temperature distribution in the metal mass during crystallization, and subsequent cooling of the metal. Metal cooling rates are calculated. It is established that the addition of metal to the thermite mixture significantly affects the temperature and carbon concentration in the depositing metal. It is shown that in the process of surfacing, the zone of thermal influence extends to the entire rail head. From non-isothermal diagrams of steel cooling, it is established that no quenching structures are formed during surfacing, but perlite structures of the metal should be formed. The calculated characteristics of the deposited metal–rail system are compared with the characteristics of metal obtained experimentally during aluminothermic welding of rails. An improved technology of aluminothermic surfacing and rail welding is proposed. According to this technology, surfacing can be performed with a preset metal composition.