Study of self-shielded flux-cored wire with exothermic additions CuO-Al on weld bead morphology, microstructure, and mechanical properties

Abstract

The weld bead morphology has a great impact on the hardfacing processes, as it determines the quality of the deposited metal and the ease of slag removal, as well as the chemical composition of the deposited metal and its cooling conditions, which ultimately determines the microstructure and phase composition, mechanical properties, and performance characteristics (such as corrosion resistance, wear resistance, etc.). In this article, the effect of exothermic addition of CuOAl system and the influence of graphiteon weld bead morphology, thermal cycle parameters, and mechanical properties were investigated using the mixture design (MD). The structural characteristics were analysed by optical microscope (OM) and X-ray diffractometer (XRD). Microhardness values of the hardfaced samples were obtained using a Vickers hardness tester. It was determined that the most weld bead parameters were observed for the flux-cored wire electrode with an average exothermic addition content at the level of EA = 26.5–28.58 wt.% and a high carbon content (low values of CuO/C = 3.75). The highest mechanical properties (high hardness) were observed for single-pass weld beads with a high content of exothermic addition (EA ≥ 33 wt.%) and a high value of CuO/Al ≤ 4.5, which provided a high content of copper in the deposited metal.