The influence of pulsed electric current modes on the structure and properties of the composite system W-steel Kh18N10T

Abstract

The work investigates the influence of technological parameters of roller contact welding on the formation of a metal matrix composite material reinforced with tungsten fibers. To assess the quality of consolidation of the composite structure, it is proposed to use the electrical conductivity measured by the eddy current method as an indirect indicator of the integrity of the melted zone and the volume fraction of internal defects. It is established that an increase in electrical conductivity corresponds to a decrease in the number of non-melts and the formation of a continuous conductive path in the fusion zone. To optimize the process of manufacturing the composite material, a fractional factorial experiment of the type 2⁵⁻² was implemented with variations in the duration of the welding current pulse, the duration of the pause, the force of electrode compression, the speed of formation and shear of welds. Based on the results of statistical processing of experimental data, an adequate regression model was obtained that describes the dependence of electrical conductivity on the technological parameters of the process. The area of optimal composite formation modes was determined by the steep ascent method. Metallographic studies have shown that the optimized parameters ensure the formation of a continuous molten zone around the reinforcing fibers while preserving the original microstructure of the surface layers of the matrix. It was established that the high-temperature short-term strength of the obtained composite materials at 1200 °C corresponds to the values calculated by the rule of mixture. Based on a comprehensive analysis of the microstructure and technological characteristics, a rational mode of forming a metal matrix composite material was substantiated. Keywords: metal matrix composite material, tungsten fiber, contact roller welding, electrical conductivity.