Lavrova O. Development of scientific and technological bases of heat and mass transfer control during electric arc surfacing using a control mechanical action on the electrode

The goal is to establish the influence of the parameters of the mechanical control action on the electrode to increase the efficiency of the electric arc surfacing process, as well as to create technology and equipment for the implementation of developments in production conditions. The object of research is the process of electric arc surfacing with the use of mechanical control action on the electrode. The subject of research is the heat and mass transfer of the electrode metal during electric arc surfacing under the influence of mechanical control actions. Research methods. When solving the tasks set in the work, the following methods and equipment were used for research: microstructural research methods, X-ray spectral microanalysis; microhardness measurements; digital oscillography of the surfacing process; mathematical modeling; computational and experimental studies using data processing software. It was established for the first time that the use of mechanical control actions on the electrode makes it possible to stabilize the droplet transfer of the electrode metal both through the arc and outside it, to reduce the droplet mass, to provide fine droplet transfer without short circuits of the arc gap, while the shape and size of the electrode determine the optimal range of control action parameters. On the basis of the developed mathematical model of the heat and mass transfer of the electrode metal when using a mechanical control action on the electrode, the size and mass of the electrode metal droplets were determined for the first time. A mathematical model of conductive heating of the base metal has been developed, which takes into account the mechanical effect on the electrode for the case of a semi-infinite body and a flat layer. The use of simulation results in the development of an optimized surfacing technology makes it possible to increase the efficiency of melting of the electrode metal with a decrease in heat input into the base metal, thereby reducing the area of melting isotherms at the level of the base metal surface to 12% with a constant value of productivity. Increasing the efficiency of melting the electrode metal due to the use of mechanical action makes it possible to reduce the heat input into the weld pool and the base metal, and this dependence has an extreme character, which reduces the coefficient of variation of the penetration depth by an average of 10%, improves the structure of the near-weld zone and increases the efficiency of the deposited layer. An increase in the melting coefficient of the electrode metal by 15–25% with the use of a mechanical control action was experimentally established and confirmed by calculation. When using a mechanical control action, the components of the "electrode-arc-weld pool" system are in synergetic interaction, determining the optimal values of the control parameters for each considered option of using mechanical control actions on the electrode. The theoretical and technological foundations of heat and mass transfer during electric arc surfacing were further developed by establishing the laws governing the melting of the electrode and base metal when using mechanical control actions on the electrode(s). The influence of control parameters on the formation of the penetration zone, deposited bead and the properties of the near-weld zone for various types of electrodes is generalized, which makes it possible to introduce energy-saving technologies for the restoration of metallurgical and rolling equipment