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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 article presents an analysis of the metallurgical techniques that provide high quality electrodes for manual arc welding of low-carbon low-alloyed cold-resistant steels. It is shown that it is possible to improve technological and operational properties of welded joints at very low climatic temperatures up to –70°C implementing micro-alloying of the weld metal with nitrogen, titanium, cerium oxide and diamond nanopowder produced by detonation synthesis. The composition introduced into the electrode coating modifier mixture is identified. The cumulative effect of its components on the weld impact strength under temperature testing within the range from –20 up to –70°C was established. The matrix of the weld metal is composed mainly of disperse acicular ferrite, hardened by nanoparticles allegedly nitrides and carbonitrides of titanium and aluminum. It is shown that the centers for the crystallization of acicular ferrite are micro-sized non-metallic inclusions formed on ultrafine titanium nitrides. It was revealed that the toughness of the weld metal at low climatic temperatures is higher than toughness of joints welded by massively imported Japanese KOBELCO electrodes LB-52U. The results of the study make it possible to increase the cold resistance of welded structures for petrochemical plants and other facilities located in the Extreme North of the Russian Federation.Part 2 of the article will be devoted to the study of the welding and technological properties of coated electrodes.

The article deals with organizational and economic problems of land management and land use in modern economic conditions. Qualitative and quantitative changes in the land Fund under the conditions of formation of a multi-layered economy are studied on the example of the Tver region. The most significant problems of land management at the state and regional level in the context of sustainable land use development are identified and specified, and directions for their solution are proposed.