Study of the hardfacing process using self-shielding flux-cored wire with an exothermic addition with a combined oxidizer of the Al-(CuO/Fe₂O₃) system

Analysis of publications has shown that the use of the exothermic addition with a combined oxidizer (xCuO + (x-1)Fe₂O₃-Al) as components of filler materials will reduce energy consumption and increase the efficiency of the welding/hardfacing process. However, in the literature, there are no studies of exothermic addition with combined oxidizers, which allow to vary the chemical composition of the deposited metal within a wide range. In this paper, the use of exothermic addition with combined oxidizer (xCuO + (x-1)Fe₂O₃-Al) was considered. To study the characteristics, standard methods were used to determine the arc stability, melting characteristics, weld bead morphology, melting-energy characteristics, and efficiency parameters, and mechanical properties were made. The structural characteristics were analyzed by optical microscope (OM), X-ray diffractometer (XRD). Microhardness values of the hardfaced samples were obtained using a Vickers hardness tester. The greater stability of arc voltage was shown by the processes performed with flux-cored wires in which oxidizing agents of exothermic addition Al-CuO-Fe₂O₃ in the core filler were taken with an equal content of oxidizing agents or with a slight excess of oxidizing agent CuO/(CuO + Fe₂O₃) = 0.5–0.6, whereas the greater stability of the welding current was shown by the processes carried out with the use of flux-cored wire with the exothermic addition with an equal or greater proportion of Fe₂O₃ oxidizer in the combined oxidizer CuO/(CuO + Fe₂O₃) ≤ 0.5. Further studies of melting characteristics (deposition rate, spattering factor, etc.), melting-energy characteristics (melt-off coefficient C_M and deposition rate coefficient C_d), and efficiency showed the efficiency of using exothermic addition with combined oxidizer of Al-CuO-Fe₂O₃ system. The study showed high arc stability of the hardfacing process, an increase in deposition efficiency (De), and a decrease in spattering loss, which increased deposition rate from 4.73 kg·h⁻¹ to 6.42 kg·h⁻¹ compared to exothermic addition with simple Al-Fe₂O₃ system. Analysis of weld bead morphology showed improvement in weld bead parameters. The results showed high energy efficiency and productivity of the welding/hardfacing process with the introduction of exothermic addition with combined oxidizer of CuO-Fe₂O₃-Al system at the following share of copper oxide in combined oxidizer CuO/(CuO + Fe₂O₃) = 0.5–0.6.