This article discusses the results of investigating the structure of chromium–nickel metal obtained through electric arc surfacing with single and double electrodes in a protective gas. It provides recommendations for forming a defect-free cladding layer by welding with double electrodes. The results show that double electrodes can achieve comparable resistance to intergranular corrosion while reducing electrode metal consumption by approximately 30–35%. Additionally, this method results in a more technologically advanced form of deposited beads.

A method and a device for testing materials for resistance to gas-abrasive wear at normal temperatures and temperatures elevated to 1000°C is developed. The test results provide a substantiated choice of surfacing materials for restoring working surfaces of parts of exhaust fans, industrial fans, top-charging gear, gas turbine units, and other equipment. The dependences of the wear of some surfacing alloys on the test temperature, gas-abrasive flow velocity, and the angle of its attack on the sample surface is determined. It is shown that under conditions of high-temperature gas-abrasive wear at small attack angles and increased speed of abrasive particles, it is advisable to use eutectic alloys with a reduced content of expensive carbide-forming elements and carbon, and at high attack angles and low-speed abrasive, heat-resistant and refractory austenitic steels. It is found that the foreign deposited C6.0Cr23Nb7Mo7W2Si2VT alloy, characterized by the highest alloying level and volume fraction of strengthening phases, has the highest resistance to gas-abrasive wear at normal temperatures among those tested. When the test temperature increases to 600°C, its wear resistance decreases by 2.5 times, yielding to the indicator of the experimental C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy. The processes of destruction of thin surface layers of alloys are studied using the electron-ion microscopy method, which makes it possible to evaluate the influence of their structural and phase composition on the high-temperature wear mechanism. The study of the wear pattern of the C2.8Cr14Ni6Mn6Mo3Ti2Nb2 alloy showed that under the impact action of the abrasive, cracks are formed in lamellar carbides Me3C2 and Me7C3, but the high plasticity of nickel-alloyed austenite reduces the likelihood of breakdown of the resulting fragments. At the same time, small carbides (Ti,Nb,Mo)xCy and Mo2C of a compact form restrain the plastic deformation of the austenite-carbide eutectic without destruction.

During the study, based on the experimental data obtained, the influence of the parameters of modulated alternating current during automatic two-electrode submerged arc surfacing on the geometric parameters of the weld bead was revealed. It has been shown that the proportion of base metal can be reduced by reducing the balance between current phases to 25% and setting the current amplitude offset to -10 V. The results obtained can be used for the operation of cladding internal surfaces of petrochemical production equipment with corrosion-resistant alloys.

This study considers the formation of an alloyed nickel aluminide structure through automatic electric arc surfacing employing an oscillating electrode composed of composite wire. The arc transversely traverses the weld pool surface at a frequency denoted as f. In comparison to conventional surfacing techniques, this process either displaces the crystallization front alongside the weld pool (at f = 1.3 Hz) or stabilizes it (at f ≥ 2 Hz) throughout the cross-sectional area of the coating layer. We have conducted an investigation into the evolution of alloy structures resulting from surfacing. Notably, we have observed that the regions with concentrations of eutectic nickel-aluminum are particularly susceptible to structural alterations. The formation of particle clusters, which is contingent upon heat dissipation conditions near the crystallization front, leads to the development of layered texture regions. Our findings reveal that following 50 thermal cycles (heating to 1100 °C, cooling to 25 °C), the alloy's hardness becomes independent of subsequent thermal cycles, consistently maintaining a level 34–35 HRC. The highest resistance of the surfaced metal to thermal fatigue cracks is achieved when its structure exhibits an optimal γ-solid solution (relatively ductile) to nickel-aluminum cooling martensite ratio, corresponding to the Ni2Al phase. The thermal conditions necessary for producing such a structure are elucidated by the gradual cooling of the crystallized metal from elevated temperatures when f ≥ 2.8 Hz. An analysis of changes in oxidative wear, estimated by mass loss, during thermal fatigue tests conducted at a metal heating temperature of 1100 °C revealed the superiority of the studied alloy over industrial alloys based on nickel and cobalt.

The work considered the influence of the main parameters of the arc surfacing in protective gases with electrode transverse oscillations on the formation of low-carbon low-alloy deposited metal. It has been defined that the range of deposited beads defect-free formation modes is quite narrow and exists in the region of high values of welding current, low values of welding rate and electrode oscillation frequency. It is shown that the heat input increase of surfacing with the constant amplitude and frequency of oscillations allows not only to improve the formation of the weld bead, but also to obtain the smoother gradient of changes properties along the height of the multilayer deposited metal and at the heat-affected zone of the base metal.

Arc travel across the surface of a weld pool melt enables a wide range of thermal impacts on the solidifying metal during the formation of a thermal and wear-resistant nickel aluminide-based alloy. The formation of a homogeneous thermal field in the weld pool at an arc oscillation frequency of 3 Hz decreases the solidification rate. Under these conditions, the structure ratio of the relatively viscous & gamma;-solid solution (Hv of 4700-4900 MPa) is highly alloyed (up to 14 wt%) with iron and other elements to nickel-aluminium martensite, and the composition of the Ni2Al-phase (Hv of 4400-4700 MPa) is close to optimal (approximately 50/50). The metal deposited in this structure indicates higher thermal resistance during temperature cycling within a temperature range from 20 degrees C to 1150 degrees C compared to that of the & gamma; + & gamma;'(Ni3Al) alloy structures formed at low arc oscillation frequencies. When the two composite wires are separated by a distance of 12 mm, the thermal impact of the arc on the weld pool melt becomes an impulse with an arc transition frequency of 11-13 Hz between the electrodes. The thermal cycle formed under these conditions provides the highest cooling rates of the melt near the solidification front, which reduces the size of the structural components and allows for the microalloying of the deposited metal with titanium diboride. The TiB2 particles in the structure enable the formation of strengthening phases, such as borides, with a high content of refractory elements (Cr, W, Mo, Ta). This increases the resistance of the deposited metal to gas abrasive wear at temperatures up to 1000 degrees C.

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.

The results of the experimental studies hardfacing of the 55NiCrMoV5 die steel of the three types of wear and heat-resistant alloys with preheating are presented. The effect of the preheating on the structure hardfaced alloys as well as on the heat affected zone formation of the base metal is estimated. It is revealed that the use of preheating under the considered conditions of surfacing causes the formation of a structural heterogeneity of the heat-affected zone of the base metal, which manifests itself as a variable distribution of chromium and molybdenum.

An analysis of the influence of the ratio of alloying elements in the Ni–Al–Cr–W–Mo–Ta system on the resistance of the deposited metal to thermal fatigue is presented. The cumulative effect of alloying elements on the resistance of the deposited metal to the appearance of cracks in conditions of cyclic temperature changes in the range of 20–1150°C has been established. It is shown that, in the alloying system under consideration, the sensitivity of the metal to the formation of thermal fatigue cracks mainly depends on the amount of refractory elements that cause the formation of topologically close-packed (TCP) phases. The content in the deposited metal of 3.5 wt % tungsten, 3.0 wt % molybdenum, and 2.5 wt % tantalum does not cause fatigue cracks. The developed type of deposited metal provides a high level of thermal and oxidative wear resistance as compared to high-alloyed industrial nickel and cobalt alloys.

The analysis of metallurgical methods that improve the quality of electrodes for manual arc welding of low-carbon and low-alloy cold-resistant steels is presented. It is shown that it is possible to increase the technological and operational properties of welded joints at ultralow climatic temperatures down to –70°C to the level of world analogs by microalloying the weld metal with nitrogen, titanium, cerium oxide, and diamond nanoparticles of detonation origin. The composition of the modifying mixture introduced into the electrode coating is revealed. The cumulative effect of its constituent components on the impact toughness of the weld metal on 10KhSND steel was established during tests in the temperature range from –20 to –70°C. The weld metal structure consists mainly of dispersed acicular ferrite, reinforced with nanoparticles, presumably nitrides and carbonitrides of titanium and aluminum. It is shown that the centers of crystallization for acicular ferrite are microsized nonmetallic inclusions formed on superdispersed titanium nitrides. It was revealed that the impact toughness of the weld metal at below-zero climatic temperatures exceeds its values for seams welded using the massively imported LB-52U electrodes of the Japanese company KOBELCO. The results of the performed research make it possible to increase the cold resistance of welded structures for petrochemical and special purposes, based in the regions of the Far North of the Russian Federation.

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.

Abstract—The wear resistance of Ti–Fe laminar intermetallic composites is compared with that of U9A and CrMoVSi1-1-1-1 tool steels. In the range 20–600°C, the wear resistance of the Ti–Fe composites is practically unchanged. Accordingly, it is below that of the tool steels at normal temperature, matches that of the steels at 500°C, and exceeds that of the U9A and CrMoVSi1-1-1-1 steels at 600°C (by factors of 2 and 1.6, respectively).

The behavior of the structure of abrasion-resistant alloys of the Fe – Cr – C – Mo – Ni – Ti – B system during electric arc cladding with introduction of ultrafine particles of titanium nitride into the welding pool in the composition of both the electrode and the filling powder wires is considered. The effect of titanium nitride on the hardness and wear resistance of the experimental clad alloys at normal and elevated temperatures is studied, and the values of the operating properties of the alloys are compared to the respective properties of the commercial counterparts.

It is shown that the introduction of micro-sized particles of refractory compounds TiB, ZrB, CeO in the composition of the filler of the composite wire (CW) contributes to an increase in the quality of mass transfer of metal in the welding arc. It was found that under the influence of particles of the considered components, melting components of the CW filler, heterogeneous in terms of thermophysical properties, are more actively formed into a metal drop, and its overheating decreases. This helps to improve the quality of transfer of the electrode metal in the welding arc and to increase the conversion factors of alloying elements into the weld metal.

The studied GMAW processes - splitting the electrode into two wires, oscillation of the electrode, and cooling the weld pool metal with filler wire - reduce the arc thermal impact on the nanoparticles and improve their mass transfer into the solidifying metal. The nanoparticles in the wire fillers are recommended to be within 0.3-0.6 wt.%. Surfacing with two composite wires containing WC nanoparticles improves the properties of metal with a Ni-3 Al -based matrix at temperatures within 1000-1200 degrees C. WC particles influence the composite metal formation, initiating precipitation from the gamma + gamma' solid solutions of strengthening phases in the form of inter-metallides of (Zr,Ta,W)C type and ZrC carbides. The surfacing process with oscillation of the electrode flux-cored wire with TiCN particles improves the thermal and plastic resistance of the metal, with a matrix of the C-Fe-Cr-Ni-Mo-Ti-N system at temperatures within 750-950 C. The composite metal with fine grains is formed under the influence of nucleation centres, in the form of TiCN nanoparticle clusters. The filler flux-cored wire with ultra-disperse TiN particles introduced in the weld pool, improves the resistance of deposited metal of the Fe-C-Cr-Mo-Ni-B system to abrasive wear at 500 C. TiN particles initiate precipitation from the deposited metal matrix of strengthening phases in the form of (Ti, Mo)C1-x carbides that are 1 similar to 4 mu m in size. In conjunction with additional cooling of the melt near the solidification front, this helps to form the MMC structure in the melt.