LAUSR

ABSTRACT The performance of permanent-welded joints of copper alloys, as well as copper, differ significantly from steel welding due to the difference in the thermophysical properties of these metals. It should be borne in mind that copper has a thermal conductivity of 6 times higher than that of iron and a linear expansion coefficient of copper is 1.5 times greater than that of steel. In this article, the authors propose a solution to one of the problems, i.e. optimisation of the thermal state of the parts to be welded. Solving this problem, a theoretical calculation of thermal conductivity in dimensionless units was performed, which indicates a significant difference in the thermal conductivity of copper and steel. To optimise the thermal state, a method was chosen to equalise the difference in physical properties by preheating the formed part by heating using a pulsed current. An analysis of the solution of this problem was carried out using the study of mechanical properties and the study of microstructure. The results showed the feasibility of using preheating to improve the quality of the weld and, as a result, increase in the durability of the welded joints with copper and steel.