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The aim of this work was to enhance the mechanical and tribological properties of an alpha titanium substrate by forming a protective cermet coating on its surface. In this study, protective cermet coatings based on titanium borides were prepared by electric arc surfacing in a protective environment. Two types of protective environment were investigated during the surfacing process: (i) inert (argon) and (ii) reactive (nitrogen). The characteristic zones of the deposited layer were established depending on the environment used, and the coating-substrate transition zone was thoroughly examined. It was demonstrated that the formation of the transition zone results from the mutual diffusion of the molten material of the electrode material and the substrate. For the first time, the formation of TiB 2 -TiN eutectic in the form of whiskers 4–20 μm wide and 100–300 μm long distributed in the matrix of the Ti(B,N) x solid solution was established when forming a protective cermet coating in a nitrogen environment. The presence of this TiB 2 -TiN eutectic led to a significant increase in the hardness of the coating, up to 4.4 times, from 350 to 1530 HV. Tribological tests of surfacing coatings were conducted, and both 2D and 3D profiles of the wear grooves are presented, providing insight into the wear mechanism. It was found that the wear resistance of the cermet coating obtained in a nitrogen environment increased by 5.2 times, while in an argon environment it increased by 3.1 times as compared to the substrate without the protective cermet coating. The results indicate the potential of the developed protective cermet coatings for use in abrasive operating conditions. [ABSTRACT FROM AUTHOR]

Using the methods of advanced material physics, the structural-phase state of a layer of high-entropy high-speed non-equiatomic molybdenum tool steel formed by electric arc surfacing in a nitrogen atmosphere is studied. The thermodynamical and mechanical (elastic moduli) properties of the surfaced layer are examined in a temperature interval of 300–1400°C, and a phase-composition diagram is presented. It is observed that a temperature increase is accompanied by an α→γ polymorphic transformation, followed by a decrease in the content of carbide phases and elastic moduli. [ABSTRACT FROM AUTHOR]

The structural changes in 09G2S steel produced by 3D printing (electric arc surfacing) under fatigue loads are studied over a broad range of temperature and cyclic stress variation. The kinetics of crack nucleation and growth in the steel is investigated. A neural network model is proposed to assess the remaining life, taking account of the microstructural evolution of the 09G2S steel in the tests. [ABSTRACT FROM AUTHOR]

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The cold strength and mechanical properties of AMg5 aluminum alloy produced by additive electric arc surfacing are considered. The mechanical properties of the 3D-printed alloy are worse than those of the rolled alloy. Quantum-mechanical calculations show that alloying with nanoparticles optimally improves the mechanical properties of aluminum alloys. Alloying with zirconium and tantalum or with titanium intermetallides is particularly effective. [ABSTRACT FROM AUTHOR]

The results of studying the formation of welded joint in electric arc surfacing on copper by the wires, providing a deposited metal based on iron and nickel, which according to the authors and publications in the technical literature, have a high resistance to different types of wear at elevated temperatures. The modes were selected and technologies of arc surfacing on a copper base by selected wires were developed, which provide a satisfactory formation of the deposited metal and its fusion with the base metal. According to the results of experiments on electric arc surfacing on copper, as well as the study of macro- and microstructure of deposited specimens, it was shown that the best results in terms of welding and technological properties are provided by the use of the nickel-based wire. The admissibility of individual defects that were found in the deposited metal and on the fusion line of the base and deposited metals during studies will be determined by the operating conditions of specific parts. [ABSTRACT FROM AUTHOR]

The strength and low-temperature stability of 09Mn2Si steel are investigated. The mechanical properties of samples obtained by 3D printing (electric arc surfacing) in CNC machine tools are close to those of samples obtained from rolled sheet. In fact, the strength and yield point after 3D printing are superior. However, the low-temperature stability of 09Mn2Si steel samples obtained by electric arc surfacing is worse than for samples from rolled sheet. The results show that electric arc surfacing is promising for the 3D printing of cold-resistant materials in CNC machine tools. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the influence of the conditions of volume electric arc surfacing on the geometric accuracy of "cube" type objects with dimensions of 20 × 20 × 20 mm made of 09Mn2Si and 06Cr19Ni9Ti steel fillers. It has been found that the actual length and width dimensions of the samples surfaced with 09Mn2Si steel generally are exceeded and the dimensions in height are smaller than the specified dimensions of the model. This may be due to the melt spreading over the substrate during the formation of the first layers. The optimal surfacing conditions for cube type objects made of 09Mn2Si steel have been defined. When surfacing the samples of 06Cr19Ni9Ti steel, spreading does not occur; however, all actual dimensions are smaller than the specified ones. This might be caused by shrinkage processes that proceed in the deposited layers during their solidification. The most optimal mode for samples made of 06Cr19Ni9Ti steel is the mode in which the reduction in length and width was no more than 2.5%, and that in height was 13.5%. Studies on the influence of the welding arc voltage and the grade of the filler material on the width of the deposited track has confirmed the tendency of 09Mn2Si steel to spread over the substrate in the entire voltage range studied (11–19 V). The microstructure of the deposited samples has been investigated. Tensile tests of the deposited samples at room temperature have shown that the samples have a set of acceptable mechanical properties that exceed the reference values. This is a proof that the deposition process occurs at a high level of quality without formation of incomplete fusion and porosity areas. [ABSTRACT FROM AUTHOR]

The structural-phase state and the distribution of microhardness over the cross section of single and double coatings deposited onto martensitic Hardox 450 low-carbon steel by alloyed flux-cored wire, are studied using modern physical materials science. It is demonstrated that the microhardness of a double deposited layer 10 mm in thickness exceeds the microhardness of the base metal by more than three times. It is found that the improved mechanical properties of the deposited layer are due to the formation of a submicro- and nanodisperse martensitic structure containing iron borides forming a plate-type eutectic. Plates of iron boride FeB are formed in the eutectic in a single deposited layer, and in a double-deposited layer, plates of FeB are formed. The existence of bend extinction contours, indicating the formation of internal stress fields at the interface between the phases of iron borides and α-iron borides, is revealed. [ABSTRACT FROM AUTHOR]

The development and application of the technology of reconditioning surfacing of the rollers of the bottom section of bearings with a high degree of wear of the working surface (up to 15 mm) are described. The main task was to ensure the required wear resistance of the deposited metal and HV10 hardness not lower than 500 mm2. This was achieved by the method of electric arc-mechanized surfacing with a consumable electrode wire with a solid cross section and a mixture of fluxes FKN-6 and OK 10.71 resulting in the required degree of alloying of the deposited metal and the required mechanical properties. The proposed technology is used for surfacing an experimental batch of rollers and has been tested in the actual production conditions. [ABSTRACT FROM PUBLISHER]

Structural-phase states and mechanical properties of electric arc surfacing by an EnDOtec DO*33 cored wire on a Hardox 400 steel are investigated. Formation of the multiphase state of the surfacing represented by grains of α-iron and inclusions of carbide phases based on iron, chromium, and niobium is revealed by the methods of electron diffraction microscopy and x-ray phase analysis. The additional treatment of the surfacing by a high-intensity electron beam is performed. Mutual arrangement of the grains of α-iron and particles of carbide phases is investigated. It is found that the surfacing layer is in the elastic-stressed state formed as a result of super-high heating and cooling rates initiated by the pulsed electron beam treatment. It is shown that the microhardness of the surfaced layer remains constant with the depth down to 4 mm and exceeds by a factor of 2.4 the microhardness of the substrate; the wear resistance of the surfacing is 3 times higher than that of the steel, and the friction coefficient of the surfacing is half that of the steel. [ABSTRACT FROM AUTHOR]

The wear resistance and feasibility of applying soil rippers have been studied after surfacing for use in the clayey soil. The study illustrates laboratory and production research of standard and novel (with large grain tungsten carbide) material for manual electric arc surfacing. Hardness and wear resistance in the clayey soil have been determined. Rippers (and the components of soil cultivating machinery yield the least wear by using wear-resistant materials and the comprehensive surfacing of tailing and lateral surfaces. It is shown that hard-alloy tips of rippers are better suited for clayey soil, which is the toughest to cultivate. The best wear resistance in clayey soil is found in hard-alloyed layers of Fe-C-Cr-Si-Mo-Nb-W and Fe-C-Mn-B alloys. The wear rate depends on the depth of cultivation and varies exponentially. [ABSTRACT FROM AUTHOR]

Influence of preheating temperature and heat input during surfacing on change of delayed fracture resistance of HAZ metal on high-strength steel at variation of carbon content in it from 0.55 to 0.75 % was investigated. Effect of carbon content in steel on indices of critical stresses at HAZ metal delayed fracture was evaluated by Implant tests. Influence of a cooling rate on nature of metal fracture and typical rupture zone and parameters of structural constituents were studied and determined using the methods of scanning electron microscopy. It is determined that HAZ metal is predisposed to the delayed fracture in electric arc surfacing due to formation of quenched structures with high dislocation density and internal stresses in area of overheating. Increase of cooling rate and carbon content in steel promotes rise of fracture susceptibility and decrease level of critical stresses to 0.07σ0.2. Formation of more plastic structures at reduction of the cooling rate in 600-500 °C temperature interval promotes increase of the delayed fracture resistance of HAZ metal on high-strength carbon steels to σcr ⩾ 0.45σ0.2 level. A diagram of effect of carbon content in steel on HAZ metal resistance to the delayed fracture was plotted in form of w6/5 = f(C). It is determined that the process of delayed fracture in HAZ metal on steel with carbon content not more than 0.60 % can be prevented at cooling rate w6/5 not more than 16 °C/s, w6/5 ⩽ 8 °C/s with 0.60-0.65 % C and w6/5 ⩽ ⩽ 5 °C/s with 0.65-0.75 % C. Under such conditions, the structures, having sufficiently high capability to microplastic strain without microcrack generation, are formed in the metal of HAZ overheating area. [ABSTRACT FROM AUTHOR]