The purpose of the study was to establish the regularities of formation of the structure, phase composition and properties of electric arc coatings of powder wires based on high-alloy (manganese) steel with niobioum carbide additions using CALPHAD method together with expiremental investigation of structure and properties and obtainig the hardfacing material with high impact arbasive wear resistance for earth moving machines equipment. Using the free energy calculations of a multicomponent system by the Calpad method, a pseudobinary phase diagram of a highmanganese steel - niobium carbide system was constructed. The use of the diagram made it possible to predict the phase and elemental composition of electric arc coatings made of powder electrode materials. The proposed alloying system allows to obtain a surface layer consisting of two phases: manganese austenite and niobium carbide in the form of dispersed inclusions. The results of measuring the hardness of the arc coatings of the proposed doping system show that increasing the content of niobium carbide in high manganese hardfacing alloy from 0 to 10 vol. % leads to an increase in the hardness of the surface layer from 20 to 35 HRC in the undeformed state and from 46 to 54 in the deformed state. The results show that the presence of disperse NbC inclusions in the amount of more than 6 % by volume increases the intensity of hardening of the surface layer during deformation due to the formation of microregions with high level of internal stresses. According to the results of theoretical and experimental researches, a system of doping of powder electrode materials was developed to strengthen the working bodies of earthmoving equipment, which operates under conditions of considerable dynamic loads in abrasive media. It is established that when alloying electrode materials based on manganese steels close in composition to 110G13L steel, niobium carbide significantly increases both the initial hardness (before deformation) and the hardness after deformation. The obtained value of the hardness of the deformed layer - 54 HRC significantly exceeds the hardness of the serial high-manganese alloys (46 HRC) hardfacings.

electric surfacing, powder wires, high manganese steel, niobium carbide, hardening

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