Flux-cored Wire Research Articles

ИМПОРТОЗАМЕЩЕНИЕ РАБОЧИХ ОРГАНОВ ДЛЯ МУЛЬЧЕРОВ

In the current conditions, there is a multifaceted urgent problem of meeting the growing demand of agriculture for modern and high-quality equipment. Mulchers for tractors, excavators and skid steer loaders are becoming more and more popular as a type of attachment. Carbide cutting elements for the mulcher have a high resource, do not require sharpening, and are not afraid of small stones in the soil. An urgent task in terms of import substitution is the organization of their production at domestic engineering enterprises, which requires information on the materials used for manufacturing. The purpose of the study is to study the details of working bodies for foreign-made mulchers and to identify domestic analogues for the organization of industrial production in the Russian Federation. Hardness of foreign-made mulcher base is 431…710 HRC; cleaner - 221; carbide plate - 1068 ... 1073; carbide crown - 1062 ... 1076, tool holder - 51 HRC. For the production of working bodies of mulchers, Russian analogues of structural materials can be used. The tool holder and base can be made of steel for castings of ordinary grades 40KhL or 35GL GOST 977-88. For the manufacture of a scraper, chromium steel grade 40X or manganese steel grade 35GL is suitable. Parts should be subjected to a heat treatment consisting of quenching and low stress relief tempering. For the manufacture of hard-alloy elements of cutters, it is advisable to use tungsten sintered alloys of grades VK8 or VK10. Hard alloy elements should be soldered with solder grades LNMts 49-9-0.2, MNMts 55-6-4 or MNMts 9-23.5, which provide high strength of steel-hard alloy joints of 350 ... 450 MPa. It is advisable to weld the scraper to the base as follows. First, the root welds are welded with Sv-08G2S solid section welding wire by semi-automatic gas welding. Then the welded joint is surface hardened with Kiswel K-700HT or WELTEK-H565 flux-cored wire by semi-automatic gas welding. This technology provides a weld with a hardness of 54…60 HRC.

Prediction of Fill Factor and Charge Density of Self-Shielding Flux-Cored Wire with Variable Composition

Prediction of Fill Factor and Charge Density of Self-Shielding Flux-Cored Wire with Variable Composition

Effect of Nano-Y2O3 on the Microstructure and Properties of Fe-Cr-C-N-Al Surfacing Alloy

In this paper, Fe-Cr-C-N-Al-Y wear-resistant surfacing alloy was prepared by open-arc surfacing with self-shielded flux-cored wire. The wear properties of the surfacing alloy were analyzed using an MLS-23 rubber wheel wet sand wear tester. The phase composition and microstructure of the surfacing alloy were analyzed using X-ray diffraction, scanning electron microscope, electron backscatter diffraction and transmission electron microscope; the strengthening mechanism and wear mechanism of the alloy were discussed. The results show that the microstructure of Fe-Cr-C-N-Al-Y surfacing alloy is composed of M + γ-Fe + M7C3 + AlN. When the content of nano-Y2O3 is 0.456 wt.%, the formability of the surfacing alloy is the best, and the wetting angle is the smallest, which is 50.8°; AlN and M7C3 precipitate the most, and the microstructure grain is the smallest. At this time, the hardness value of the surfacing alloy is up to 62.3 HRC, which is 11.8% higher than that of the unmodified surfacing alloy. The minimum wear weight loss is 0.125 g, and the wear resistance is increased by 41.86%. The wear mechanism of the surfacing alloy is mainly a plastic deformation mechanism, and the material removal processes are microcutting and furrow wear. This study provides theoretical guidance for refining primary carbides and improving the wear resistance of high chromium cast iron.

Study of the properties of the metal deposited with flux-cored wire of the Fe‒C‒Si‒Мn‒Сr‒W‒V system.

Alloys of the Fe‒C‒Si‒Мn‒Сr‒W‒V system widely used for hot-rolling roll repairs provide high resistance of the deposited layer against abrasion, but its thermal endurance is relatively low. It is shown that in order to ensure the quality of roll repair, it is necessary to improve the composition of the flux-cored wire charge and the technology of their use. It is proposed to reduce the structural heterogeneity of the deposited metal the use of flux-cored wire of the type PP-Np-35V9X3SF. The influence of the introduction of carbon-fluorinated elements and titanium on hydrogen concentration, microstructure, level of pollution by non-metallic inclusions, grain size, hardness and rate of wear of the deposited metal layer was evaluated. The data on the chemical composition of the deposited layer, the content of non-metallic inclusions in it, the microstructure of the deposited metal, depending on the content of titanium in the flux-cored wire, are presented. It was found that an increase the concentration of titanium increases the hardness of the deposited layer and reduces the rate of wear (abrasion) of samples. The effect on the level of contamination of the studied fused layers with oxide inclusions was not revealed. Increasing the hydrogen content in the deposited layer re-duces its hardness and increases the rate of wear of the deposited layer. Increasing the content of titanium in the depos-ited layer helps to reduce the size of the martensite needles, as well as the size of the former austenite grain. The de-pendencies of HRC hardness and wear resistance on the content of titanium and hydrogen in the deposited layer were established

Pulsed TIG Cladding of a Highly Carbon-, Chromium-, Molybdenum-, Niobium-, Tungsten- and Vanadium-Alloyed Flux-Cored Wire Electrode on Duplex Stainless Steel X2CrNiMoN 22-5-3

The hardfacing process aims to increase the life span of structural components in the petrochemical, mining, nuclear and automotive industries. During operation, these components are subject to demands of abrasion wear, cavitation erosion and corrosion. Duplex stainless steels are characterized by high mechanical characteristics and corrosion resistance, but poor behavior to abrasive wear and cavitation erosion. The improvement in wear resistance is possible by selecting and depositing a special alloy on the surface using a joining technique that ensures a metallurgical bonding between the layer and the substrate. The experimental investigations carried out in this work demonstrate the ability of the TIG pulsed welding process to produce layers with good functional properties for engineering surfaces. The “Corodur 65” alloy was deposited on a duplex-stainless-steel substrate, X2CrNiMoN22-5-3, using a series of process parameters that allowed for the control of the cooling rate and heat input. The properties of the deposited layers are influenced not only by the chemical composition, but also by the dilution degree value. Since the deposition of layers through the welding operation can be considered as a process with several inputs and outputs, the control of the input parameters in the process aims at finishing the granulation and the structure in the fusion zone as well as limiting the segregation phenomena. The aim of this work is to investigate the microstructural characteristics of the iron-based alloy layer, Corodur 65, deposited via pulsed current TIG welding on duplex X2CrNiMoN22-5-3 stainless-steel substrates.

Grain refinement of Fe3Al-based iron aluminide fabricated using wire-arc additive manufacturing

The preparation of Fe3Al-based iron aluminide compounds through WAAM presents significant potential for various applications. However, iron aluminide wire is difficult to prepare due to its inherent brittleness, twin (Fe + Al) wires forming is commonly used at present, this method tends to produce large columnar grain sizes owing to excessive heat input, which also constrains the performance of material. To address these challenges, this study proposed a method based on a single Fe3Al flux-cored wire and weaving arc deposition technique to refine the grain size and improve the mechanical properties through the addition of TiC particles. The mechanical properties and microstructure of as-prepared Fe3Al were also investigated to reveal the strengthening mechanism. In short, this research provided new insight for preparing iron-aluminum compounds through WAAM.

Storage of High-Strength Steel Flux-Cored Welding Wires in Urbanized Areas

The condition of the consumables is a key factor determining the waste reduction in the welding processes and the quality of the welded joint. The paper presents the results of tests of four types of flux-cored wires dedicated for welding high-strength steels, stored for 1 month and 6 months in Poland in two urbanized areas: in a large seaside city (Gdańsk) and in Warsaw, located in the center of the country. The wires were subjected to macroscopic and microscopic (stereoscopic, SEM) observations, EDS analysis, technological tests assessing elastic properties and targetability. The degree of degradation of the wires was also tested using resistance measurements. In order to assess the effect of storing wires on the weldability of steel, the diffusible hydrogen content in deposited metal was determined by high-temperature extraction. It was found that the storage caused changes in the surface condition of the wires, affected their elasticity and electrical properties, which affects the behavior of the wires during welding. A significant influence of storage conditions on the hydrogenation of deposited metal was found: in the case of three types of wires, the level of low hydrogen processes was exceeded and the maximum result was 15.18 ml/100 g of deposited metal. It was also found that copper-plated wire showed a significantly increased resistance to storage conditions compared to non-copper-plated wires.

SELECTION OF A WELDING ELECTRODE TO PREVENT CONTACT CORROSION OF A STEEL 1.0402 WELD JOINT

Welded structures operate, as a rule, under conditions of simultaneous exposure to aggressive media and workloads. Thus, when protecting the metal of welded joints from corrosion fatigue, a number of specific problems arise due to the heterogeneity of their structure, the presence of multilayer welds, physical and geometric stress concentrators, and the staged nature of the change in the fine structure of the metal during fatigue loading. The result is an accelerated destruction of the metal in the junction zones of various structural forms, which are unequally adapted to the action of fatigue stresses. This fully applies to such critical structures of the oil and gas industry as pipelines, tanks, gas holders, etc. The purpose of the research was to establish the features of corrosion of welded joints made by various brands of electrodes by analyzing the change in the value of the electrode potential of the metal, which reflects the level of free energy of the surface layers in dynamics. Laboratory samples of carbon steel 1.0402 were subjected to manual arc welding (OZL-6, LB-52, MP-3 electrodes) and semi-automatic welding (EMK 6D polished wire and E71T1 rutile flux-cored welding wire with rapidly crystallizing slag). Further, their microstructural analysis was carried out and the hardness of various sections of welded joints was determined. It has been established that samples welded by semi-automatic welding are less susceptible to corrosion damage, since the distribution of electrode potentials in the zones of the welded joint indicates their lower structural inhomogeneity. In this case, general uniform corrosion takes place. In addition, the use of EMK 6D and E71T1 welding wires ensures better mechanical properties of welded joints.

Influence of Silicon Carbide Introduced into a Flux-Cored Wire Charge on Deposited Metal Structure

Influence of Silicon Carbide Introduced into a Flux-Cored Wire Charge on Deposited Metal Structure

The Efficiency of Thermite-Assisted Underwater Wet Flux-Cored Arc Welding Process: Electrical Dependence, Microstructural Changes, and Mechanical Properties

Alumino-thermic additions to the flux-cored wire can be utilized to enhance welding heat input, improve welding productivity, and minimize the dependency on power sources in the air environment. In this article, the influence of Al/Fe2O3 thermite on electrical dependency, microstructural characteristics, and mechanical performance during the underwater wet welding of Q235 steel was investigated. The results revealed that adding exothermic flux enhanced the underwater wet welding appearance. The basicity of the slag steadily decreased from 1.77 to 0.73 because of the formation of Al2O3. Thermite increased the quantity and diameter of inclusions in the underwater wet weld metal. The excessive addition of Al/Fe2O3 thermite resulted in agglomerated inclusions in the weld metal. Significant microstructural changes from grain boundary ferrite to acicular ferrite were mainly caused by the de-oxidation products of the thermite process. When thermite was added to the flux-cored wire, the ultimate tensile strength first increased and then decreased, while the microhardness of the underwater wet welds showed an obviously increasing trend. The addition of exothermic flux additions to the flux-cored wire can help generate chemical heat and increase the energy required to melt the wire. This study established a link between thermite addition and joint performance, paving the way for the development and application of thermite-assisted self-shielded flux-cored wire.

Effect of Heat Input on Microstructure and Mechanical Properties of Deposited Metal of E120C-K4 High Strength Steel Flux-Cored Wire.

The effect of different heat inputs of 1.45 kJ/mm, 1.78 kJ/mm and 2.31 kJ/mm on the microstructure and mechanical properties of deposited metals of the self-developed AWS A5.28 E120C-K4 high strength steel flux-cored wire was studied by optical microscope, scanning electron microscope and mechanical property test. With the increase in heat input, the results showed that the microstructure of deposited metals became coarse. Acicular ferrite increased at first and then decreased, granular bainite increased and degenerated upper bainite and martensite decreased slightly. Under the low heat input of 1.45 kJ/mm, the cooling rate was fast and the element diffusion was uneven, which caused composition segregation and easy to form large size inclusions SiO2-TiC-CeAlO3 with weak binding to the matrix. Under the middle heat input of 1.78 kJ/mm, the composite rare earth inclusions in dimples were mainly TiC-CeAlO3. The dimples were small and uniformly distributed, and the dimple fracture mainly depended on the wall-breaking connection between medium-sized dimples rather than an intermediate media. Under the high heat input of 2.31 kJ/mm, SiO2 was easy to adhere to high melting point Al2O3 oxides to form irregular composite inclusions. Such irregular inclusions do not need to absorb too much energy to form necking. Finally, the integrated effects of microstructure and inclusions resulted in the optimum mechanical properties of deposited metals with a heat input of 1.78 kJ/mm, which was a tensile strength of 793 MPa and an average impact toughness at -40 °C of 56 J.

Structure of Modified Wear-Resistant Coatings and Technological Characteristics of Flux-Cored Wires

Structure of Modified Wear-Resistant Coatings and Technological Characteristics of Flux-Cored Wires

Laser-Assisted Flux-Cored Arc Welding Underwater

The underwater welding process using flux-cored electrodes presents a significant challenge in terms of reliable arc ignition and stability. Therefore, the aim of this study is to investigate an underwater welding process that combines laser radiation with an arc to improve seam quality by introducing additional energy into the process zone. To examine the arcs safe ignition and stability during welding, various process parameters are evaluated by analyzing the resulting arc current and voltage characteristics, as well as the spectral process emissions. S235JR (1.0038) steel samples with a thickness of 10 mm are welded in a bead-on-plate configuration using flux-cored wire. The laser radiation with a wavelength of 1030 nm and a power of up to 2000 W has a supporting effect, influences the arc positively in that it fluctuates less and ensures a more uniform weld. The laser-assisted flux-cored welding process resulted in an improved seam quality with reduced surface pores and increased weld penetration depth and width. The requiered laser power for arc stabilization was about 20-30 % of the total energy balance. The arc current and voltage characteristcs also showed a reduction of up to 70 % in fluctuation. Overall, this study demonstrates that the laser-assisted flux-cored welding process presents a promising approach to overcome the challenges of underwater welding.

Effect of Heat Input on the Microstructure and Mechanical Properties of Local Dry Underwater Welded Duplex Stainless Steel

Duplex stainless steel welded metals were underwater local dry prepared on S32101 lean duplex stainless steel trapezoidal groove plates with a self-made drain cover employing Supercore 2205P flux-cored filler wire. Different heat inputs were employed to investigate the effects on mechanical characteristics and the microstructure of welded metals. The results demonstrated that as the heat was applied, austenite concentrations in the weld metals increased. It was found that the austenite concentration and the fraction of Σ3-austenite twin-grain boundaries followed the same trends. With increasing heat input, the recrystallized ferrite and austenite grains initially decreased and subsequently increased, whereas the fraction of interphase boundaries between special ferrite and austenite exhibited the reverse trend. With a heat input of 1.4 kJ/mm, the toughness and plasticity of the weld metals were enhanced by an increase in austenite content, Σ3 recrystallized grains, and austenite twin-grain boundaries. The plasticity and tensile strength values of the welded metal changed more when the heat input was raised from 1.0 to 1.2 kJ/mm than when it was raised from 1.2 to 1.4 kJ/mm. Considering energy conservation, it is recommended to adopt 1.2 kJ/mm for welding heat input.

Research on the Microstructure and Properties of a Flux-Cored Wire Gas-Shielded Welded Joint of A710 Low-Alloy High-Strength Steel

In this study, a 16 mm thick A710 low-alloy high-strength steel was welded by using flux-cored wire gas-shielded welding with an E81T1-Ni1M flux-cored wire. The microstructure characteristics and mechanical properties of the joints were systematically studied. The results showed that the joint was well formed without obvious welding defects. The center of the weld was mainly needle-like ferrite, the coarse grain area was mainly slat-like and granular bainite, and the fine grain area was mainly ferrite and pearlite. The lowest hardness in the weld area was the weakest area of the joint. The average tensile strength of the joint was 650 MPa, reaching 95% of the base metal; the samples were all fractured in the weld area, and the fracture morphology showed typical plastic fracture characteristics. The low-temperature (−40 °C) impact energy of the joint weld area and the heat-affected zone were 71 J and 253 J; the fracture morphology was characterized by a ductile–brittle mixed fracture, and the ductile area of the specimen fracture in the heat-affected zone was larger. The bending performance was good. Under the specified life of 2 × 106 cycles; the median fatigue limit and the safety fatigue limit were 520 MPa and 492 MPa, and the fatigue cracks germinated on the surface of the priming weld.

Comparative studies of the three-body abrasion wear resistance of hardfacing Fe-Cr-C-B-Ti alloy

In this research, the mechanical and tribological properties of two deposited metal of Fe-C-Cr-B-Ti alloying systems. In this study, comparative tests of the deposited metal hardfacing by two self-shielded flux-cored wires electrode were carried out: with an exothermic additive (110Cr4Cu5Ti1MnVB) and without an exothermic additive (140Cr15TiSi1MnVB). Abrasive wear resistance was evaluated using a slightly modified procedure on a standardized tribological machine for abrasive wear, according to the limits established by the ASTM G65. The results of studies of the efficiency of introduction of an exothermic addition CuO-Al system into the core filler of a flux-cored wire electrode were presented.

Effect of the technological parameters of plasma-arc spraying of flux-cored wire on the structure and properties of intermetallide coatings based on Fe3Al

Existing techniques for applying intermetallide layers are characterized by low productivity, difficulties associated with the maintenance and operation of technological equipment, as well as significant costs for the purchase of materials for spraying. Therefore, modern science shows considerable interest in the development of new, highly effective technologies to form intermetallide coatings on the surface of articles. Such promising techniques include the technology of plasma-arc spraying (PAS) of flux-cored wires. This technique has a number of significant advantages, namely high performance, relative simplicity, as well as the affordability of equipment and materials for coating. This paper reports a study into the structure and properties of coatings obtained by flux-cored wire PAS, in which the steel sheath and aluminum powder filler interact when heated with the exothermic effect of Fe3Al synthesis. The influence of technological parameters of PAS process on the structure and properties of Fe-Al coatings was investigated by means of mathematical planning of the experiment. It was found that in all samples the main phase is an intermetallide of the Fe3Al type. Tests for gas-abrasive wear resistance at room temperature showed that the wear resistance of coatings exceeds the stability of steel S235 by an average of 2 times. As a result of studying the electrochemical properties in a 3-% aqueous solution of NaCl and in a 0.5-% solution of H2SO4, the score of corrosion resistance for these media was determined, which was, respectively, 4 and 5 (coatings belong to the group of "resistant"). In this regard, the practical use of coatings based on the Fe3Al intermetallide is recommended for protection against oxidation, corrosion, and gas-abrasive wear of components and assemblies in the heat power industry (heat exchanger pipes, catalytic converters, steam turbine blades, shut-off valves, etc.)

Study of the Microstructure and Properties of the Butt Joint of Laser-Welded Titanium Alloy with Flux-Cored Wire

A self-developed Ti-Al-V-Mo system titanium alloy flux-cored wire was used to join the Ti64 titanium alloy plate via laser welding with filler wire. The microstructure and properties of the obtained welded joint were investigated. The results showed the WM (welded metal) of the welded joint consisted mainly of acicular α’ martensite, and the HAZ (heat affected zone) was comprised of a primary αp phase, Widmanstatten, and a few α’ martensite and a residual β phase. The strength and elongation of the welded joint after breaking are equivalent to that of the BM (base metal). The tensile fracture, presenting as a microvoid coalescence ductile fracture, was encompassed by massive shear lips with deep and uniform dimples. The overall microhardness of the welded joint was sequenced as WM > HAZ > BM. In the WM, large-angle grain boundaries with intragranular misorientation greater than 15° accounted for about 84%. By XRD, it was discovered the welded joint was mainly composed of the α’ martensite, with a modest amount of extremely weak multi-angle α phase diffraction peak. The test results showed the designed welding method of titanium flux-cored wire and laser wire filling is suitable for high-quality welding of titanium alloy plate.

Comparative Study on Laser Welding Thick-Walled TC4 Titanium Alloy with Flux-Cored Wire and Cable Wire

In the welding process of thick-walled titanium alloys, the selection of the wire type is one of the critical factors affecting the welding quality. In this paper, flux-cored and cable wires were used as filler materials in the welding of thick-walled titanium alloys. The macrostructure, microstructure, texture, and grain size of both welded joints were compared by employing an optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM), and the tensile and impact properties were also evaluated. The comparison result showed that the fusion zone microstructure of both welded joints was dominated by a basketweave structure composed of interwoven acicular α' martensite, whereas the microstructure of flux-cored wire welded joints was finer, and the degree of anisotropy was low. The strength of both welded joints was higher than that of the base metal, ensuring that fracture occurred in the base metal area during tension. The Charpy impact energy of the flux-cored wire welded joint was 16.7% higher than that of the cable wire welded joint, indicating that the welded joint obtained with the flux-cored wire performed better in the welding process of thick-walled titanium alloys.

Effects of flux-cored arc welding technology on microstructure and wear resistance of Fe-Cr-C hardfacing alloy

This research presented the effects of flux-cored arc welding (FCAW) with and without preheating, gas-shielding and buffering conditions on the microstructure and wear resistance of Fe-Cr-C hardfacing alloy. The flux-cored wires based on austenitic nickel and Fe-Cr-C alloyed steel were used as buffer and hardfacing layers. The welding quality was inspected by visual test (VT) and penetrant test (PT). The structural characteristics were analyzed by optical microscope (OM), X-ray diffractometer (XRD), and scanning electron microscope with energy dispersive X-ray spectrometer (SEM-EDS). The results exhibited that the preheating, gas-shielding and buffering could improve the quality, dilution and weldability of the hardfacing weld. The structural phase of the hardfacing weld was found in the form of (Fe,Cr)7C3 mixed with martensite-austenite matrix (MA matrix). The buffering could combine the interphase of hardfacing to structural steel base resulting in the reduction of crack and carbide precipitation (Fe3C) at the fusion line from the effect of elemental dilution. The combination of buffer and hardfacing layers affected to crystallite size and fraction ratio of (Fe,Cr)7C3 to MA matrix increasing the elemental diffusions. According to the wear testing results (hardness, impact and abrasion), it was found that the preheating, gas-shielding and buffering FCAW provided an excellent wear resistance of Fe-Cr-C hardfacing alloy due to the present of (Fe,Cr)7C3 eutectic carbide in a high fraction of MA matrix resulting in good toughness-hardness balance properties. In addition, the suitable FCAW condition from the study could be applied for hardfacing of the tooth plate of crushing roller that was used in the biomass energy industry with better service life than traditional FCAW.