The relationship of average and partial coefficients of element transition in manual arc welding

In this work the procedure of the estimation of average and partial factors of the conversion of elements in manual arc welding is described. In welding by coated electrodes the composition of deposited metal and its technological welding properties depend on conditions of rod melting and coating and the interaction of the formed phases with each other and with the gas. The composition of the deposited metal can be determined, if general, average conversion factors of elements are known. The latter are found most frequently experimentally for specific conditions of welding which does not make it possible to ensure the forecast correctness in changed conditions. In this connection, the task was set to develop the procedure of the determination of partial conversion factors of elements, i.e., conversion factors at each stage of heating and melting, and their dependence on the parameters of welding conditions. During electrode melting the following processes in the arc gap proceed, such as: - melting of the electrode rod and the formation of metal drops; - melting of the metallic part of the electrode coating (ferroalloys) and the formation of metal drops; - melting of the nonmetallic part of the electrode coating (oxides, organic compounds) and the formation of slag drops; - removal of gaseous components from the welding zone; - restoration of metallic components from slag oxides. The common conversion factor of the element shows what element share is lost in the process of welding. The analysis of the processes, which take place during heating and melting of the electrode, enabled to find the interrelation between general (average) conversion factor and partial coefficients which is expressed quantitatively. Equations are found which allowed on the basis of experimental and reference data to find partial conversion factors of elements. The experiment made it possible to find the values of welding and slag baths masses with the assigned regime parameters, and also to establish dependence between welding and slag baths masses and the arc power. Partial and average conversion factors of carbon and manganese into the weld metal in manual arc welding by electrodes UONI 13/55 with a diameter of 4 mm. were calculated. As a result of data processing regression equations are obtained for the calculation of partial conversion factors depending on the regime parameters, which can be used for predicting the composition of the deposited metal.