Metallographic studies of the microstructure of the experimental type of the deposited alloy of the Fe - C - Cr - Ni - Mn - Mo - Ti - Nb alloying system were performed. The chemical and granulometric composition of the metal-strengthening phases has been determined. The weld metal was tested for resistance to gas-abrasive wear at elevated temperatures. The wear resistance of the deposited metal was diagnosed by sclerometry with obtaining images of tracks from the indenter using atomic force microscopy. The character of microplastic deformation of worn surface layers of the alloy is investigated. The influence of the structural phase composition and hardening phases in the deposited metal on its wear resistance is discussed. Promising ways to further increase the resistance of the experimental alloy to gas-abrasive wear are determined.

Compositions of flux-cored wires for electric arc surfacing of alloys of the Fe-Cr-Ni-Mn-Mo-Ti-Nb-C alloy system, resistant to high-temperature gas-abrasive wear, were developed. The deposited alloys were studied by optical and electron microscopy, X-ray mi-crospectral and X-ray diffraction analysis. The influence of the carbon content in the alloy on its structural-phase composition, hardness, and wear resistance at normal and elevated temperatures up to 600°C was revealed. It was established that increasing the carbon content in the alloy from 1.2 to 2.8 wt. % leads to increasing the volume fraction of (Cr, Fe)xCy carbides involved in the formation of the eutectic austenite-carbide matrix of the alloy at 6 times. Their morphology also changes from (Fe, Cr)23C6 to (Fe, Cr)7C3. In this case, the content of (Ti, Nb, Mo)xCy and MoxC carbides in the alloy changes insignificantly, and their average size increases by 10%. It has been established that the formation of a composite structure in the alloy contributes to its high resistance to gas-abrasive wear at a temperature of 600°C. The wear resistance of the developed alloy is comparable to a foreign industrial analogue at a much lower cost.

The analysis of the main industrial and experimental types of wear-resistant surfacing alloys is carried out. The influence of the structural-phase composition and hardening phases in the deposited metal on its wear resistance is discussed. It is shown that the optimal ratio of the volume fractions of the plastic matrix and hard phases in the structure of the deposited alloys, which provides high resistance to gas-abrasive wear, largely depends on the angles of attack. The formation of hardening phases in the form of large inclusions of chromium carbides, as well as small high-hardness carbides of niobium, molybdenum and vanadium contributes to an increase in the wear resistance of alloys in a wide range of angles of attack. High ductility and resistance to oxidation of the matrix metal is provided when it is formed on the basis of γ-Fe due to alloying of the alloy with nickel. Alloying the weld metal with large amounts of carbon and boron is not desirable, since it greatly increases the brittleness of the metal, deteriorating its technological properties.

Experiments proved that the arc voltage influences its spatial form and electrode metal transfer behavior characteristics during twin electrode GMAW with a single power source. Two specific arc forms were revealed for two corresponding types of metal transfer. The V-shaped arc exists on the melt drop common to the two consumable wires at voltage rate 24-27 V. The columnar shaped arc is formed due to voltage increase up to 34-36 V, which results in increased mobility of the cathode spot in the weld pool surface. As a result, the arc travels between the ends of two electrode wires, and the metal is transferred in drops of small size. It was demonstrated that for the common drop formation the gas mixture of 82% Ar+18% CO2 is preferable to pure argon. It decreases the surface tension on the boundary between the melted electrode metal and the vapor-gas mixture, resulting in the increased volume of the common drop. It was found that a consistent common arc from two electrode wires decreases dilution is made up 43%, which is 1,65 times more and improves the deposited metal formation quality.