Search

An innovative electroslag remelting furnace with a water-cooled electrode was introduced to recycle the rejected electrolytic manganese metal (EMM) scrap. To clarify the desulfurization process in the rejected EMM scrap, a transient three-dimensional comprehensive numerical model was elaborated. Using the magnetic potential vector approach, the respective electromagnetic fields were calculated via the Maxwell equations. The Lorentz force and the Joule heating fields were derived as phase distribution functions and interrelated via the momentum and energy conservation equations as source terms, respectively. The molten manganese metal droplet motion, as well as the fluctuation of the slag–metal interface, was described by the volume-of-fluid (VOF) approach. Besides, the solidification was modeled via the enthalpy-based technique. A thermodynamic module was established to estimate the sulfur mass transfer rate between the molten manganese metal and the molten slag. Furthermore, a factor related to the magnitude and frequency of the alternating current and the physical properties of the melt was introduced to include the electro-emulsification phenomenon. An experiment has been carried out with a commercial-scale ESR device. The predicted values of the slag temperature and sulfur content in the final manganese ingot were found to agree reasonably with the corresponding measured data. Under continuous melting of the rejected EMM scrap, molten manganese metal droplets are formed at the domain inlet, grow, and fall down. Highly conductive molten manganese metal droplets significantly change distributions of the current streamline, the Joule heating, and the Lorentz force around and within it. Moreover, droplets are inclined to rotate and move inside the mold. With the renewal of the slag–manganese interface, sulfur in the molten manganese metal is constantly transferred to the molten slag. With the applied current ranging from 3000 to 4000 A, the average sulfur content of the manganese ingot dropped from 0.0447 to 0.0291 pct, and thus, the desulfurization rate rose from 55.3 to 70.9 pct. [ABSTRACT FROM AUTHOR]

In this paper, an intelligent data-driven optimization scheme is proposed for finding the proper burden surface distribution, which exerts large influences on keeping blast furnace running smoothly in an energy-efficient state. In the proposed scheme, production indicators prediction models are first developed using a kernel extreme learning machine algorithm. To heel, burden surface decision is presented as a multiobjective optimization problem for the first time and solved by a modified two-stage intelligent optimization strategy to generate the initial setting values of burden surface. Furthermore, considering the existence of the approximation error of the created prediction models, feedback compensation is implemented to enhance the reliability of the results, in which an improved association rule mining method is developed to find the corrected values to compensate the initial setting values. Finally, we apply the proposed optimization scheme to determine the setting values of burden surface using actual data, and experimental results illustrate its effectiveness and feasibility. [ABSTRACT FROM AUTHOR]

The influence of temperature on the microstructure and physical properties of corundum refractory for blast furnace are investigated by a high-temperature test. The results show mullite and glass phases are generated by the in situ reaction in the matrix of corundum brick under high temperature. With the increase in temperature, the net structure is gradually formed in the matrix, and the multi-porous entirety is finally formed in the matrix at 1500°C. The cold compressive strength of corundum sample increases first and then decreases with the increase in temperature. The flexural strength of corundum sample is the highest at 1150°C, while with further increasing of temperature, the flexural strength of corundum sample decreases. The apparent porosity of corundum sample is the lowest at room temperature, but the apparent porosity of corundum sample fluctuates within the same level after the temperature exceeded 1150°C. [ABSTRACT FROM AUTHOR]

Review of some PWI works on creation of advanced technologies of welding the equipment for enterprises of power engineering sector of Ukraine is presented. approaches to producing welded rotor structures, and combined joints of high-temperature components of equipment of thermal power plants are described. information on improvement of the technology of welding thick-walled pipe elements from 10GN2MFA steel for NPPs is generalized. The gained experience forms the basis for solving new problems in the power engineering sector of the country. [ABSTRACT FROM AUTHOR]

The cleanliness level in the slabs of micro-alloy structure steel produced in the BOF–CAS–CC process was studied by optimizing the compositions of molten steel and refining slag in trial heats. When the slag composition was controlled in the range of CaO = 45–53 wt%, Al2O3 = 28–32 wt%, SiO2 = 6–11 wt% and MgO = 5–10 wt% in CAS, the steel composition should be in the range of [Als] = 0.025–0.035 wt% and a[O] = 0.8–1.5 ppm. After CAS treatment without feeding calcium, the results showed that the removal ratio of total oxygen content increased to 61% and the nitrogen content decreased from 34 to 13 ppm in the improved process. The residual micro-inclusions in slabs mainly consisted of SiO2–Al2O3–TiO2 and sulfides, and the particle size was predominately below 5 μm. [ABSTRACT FROM AUTHOR]

Vanadium mining and smelting activities were increasing extensively and causing serious vanadium pollution in soil around the mining area. Different existing forms of vanadium had different biological effects and the exchangeable state had been recognized as a severe threat to biodiversity and ecosystem functioning. At present, the research on vanadium morphology had not received much attention. In this study, the area that we researched had been severely polluted with vanadium due to mining and smelting activities. The changes in the morphology of vanadium in soil were studied by adjusting the organic matter content, clay mineral content, pH value, and Eh value. The results showed that at pH 8 and for 1% of humic acid added, the exchangeable fraction of vanadium in the slag was 10% and 9%, respectively, which was 5% and 6% lower than the control group. The addition of kaolin and the redox change had little effect on the exchangeable fraction of vanadium, with a change of only about 2%. To control the soil pollution caused by slag and to repair its ecological characteristics, kaolin and humic acid were used for the repair test. The results showed that after 1% humic acid mixed with 8% kaolin was added in soil, the germination rate of ryegrass reached 95% and grew flourishingly which is significantly better than other treatment groups. Our research can provide a reference for future vanadium pollution control, especially in the morphology of vanadium research. [ABSTRACT FROM AUTHOR]

The ironmaking industry in China is developing rapidly. This paper discusses the status, technological progress, issues, and possible development directions of ironmaking in China. Because the standards for waste discharge and energy consumption have become more redundant, the steel production capacity has decreased by ∼145 million tons from 2016 to 2018. New sintering and coking technologies, such as water vapour spray sintering, high-temperature exhaust gas sintering, and semi-coke utilization, have led to distinct energy and efficiency improvements. Moreover, blast furnaces (BFs) are becoming larger and more intensive, due to which labour productivity has increased noticeably. However, some issues still remain, such as high fuel ratios, hot blast temperatures, and BF longevity. Nevertheless, eco-friendly and intelligent ironmaking is gaining importance and could be the development directions of the future. [ABSTRACT FROM AUTHOR]

Kinetic modeling of ladle refining can be used by steel plants to improve steelmaking and to produce cleaner steels. It can also help researchers to understand the process better. There have been several recent attempts to develop a kinetic model that can predict changes in steel, slag, and inclusion compositions with time. Often the models require parameters that can be difficult to measure under plant conditions, and model limitations have not been discussed in detail. In this study, a two-parameter kinetic model has been developed to predict changes in steel, slag, and inclusion compositions during ladle refining; the two parameters are the mass-transfer coefficient in steel and the inclusion flotation rate constant. The model was based on FactSage macro-processing. Examples of results show that the model can be used to diagnose effects of steel and slag sampling practices and to estimate alloy dissolution time. The model results demonstrate that the presence of solids in slag can significantly reduce the rate of steel–slag reaction while maintaining a high inclusion flotation rate. Some limitations of the model are discussed: the overprediction of calcium transfer to alumina inclusions and the absence of information on inclusions originating from entrained slag. [ABSTRACT FROM AUTHOR]

The formation analysis of the weld metal chemical composition during welding of bridge structures made of 10ХСND steel under the flux over a layer of granular modifying additive is given. It is shown that the chemical composition of the weld metal is determined not only by the composition of the materials involved in the welding process, but also by the trajectory of their delivery to the weld pool. The greatest effect of grinding grain in the weld metal takes place when the modifier enters the bath, bypassing the arc column. On the grounds of thermodynamic analysis it is shown that at welding over a layer of granulated additive, titanium dioxide modifying particles are captured by liquid metal flows, bypassing the process of dissociation. At the same time the refractory particles of the intermetallide compound TiAl2O5, which are the nuclei of the solid phase in the crystallization zone of the weld pool, are formed as a result of interaction with aluminium oxide coming from the flux. The relationship between the particle size of TiO2 in the composition of the granular additive and the size of non-metallic inclusions in the seam is established. [ABSTRACT FROM AUTHOR]

The influence of kind and type of electrode wire, characteristics of its melting, as well as composition of shielding gas, on welding-technological properties and technological quality of welds in joints of low-alloyed steels of increased and high strength is considered. The ways and means of achieving a consistently high technological quality of welds, increasing the efficiency of the process and reducing the level of gross evolutions of welding fumes are noted. 14 Ref., 4 Figures. [ABSTRACT FROM AUTHOR]

Existing methods of determining the onset of slag flow in the discharge of liquid steel from the casting ladle to the tundish are analyzed. Two aspects are considered: (1) selection of the best method of generating a diagnostic signal in terms of cost and quality; (2) development of a method of signal processing so as to derive useful information. The proposed method is to obtain a vibrational-acceleration signal from a sensor on the protective-tube manipulator in the casting ladle. A prototype is developed for installing the sensor on the manipulator. This prototype protects the sensor from industrial disturbances. In signal analysis, the onset of slag flow is determined by calculating the entropy energy. The corresponding system is tested in an industrial casting system. To ensure effectiveness of the approach, a manual subsystem maintaining the steel level in the tundish in the last stage of casting must be introduced, so as to rule out perturbations associated with motion of the gate valve controlling the flow of steel melt. Industrial experiments indicate that the automatic system must be switched off when the ladle contains only around 18–19 t of steel. In tests, the operator has always been able to select the casting rate such that the steel level in the tundish is consistent with the regulations. As a result, the algorithm triggers slag segregation for each casting run before the operator does so. When using this method, the steel residue with the slag in the casting ladle differs by no more than 3.8 t from the value for slag segregation by the operator. [ABSTRACT FROM AUTHOR]

A comparative analysis of the welding-technological properties, chemical composition and mechanical properties of the weld metal of chromium-molybdenum-vanadium heat-resistant steel, performed by submerged arc welding, has been carried out. A significant increase in the productivity of welding on alternating current without deterioration of any indicators of the mechanical properties of the weld metal has been established. The prospects of using sources of welding arc of alternating current at the manufacture of equipment for nuclear reactors in the case of using agglomerated welding flux from the point of view of improving welding performance and resistance characteristics to brittle fracture of the weld metal are shown. [ABSTRACT FROM AUTHOR]

When steel smelted in a basic oxygen converter at an increased specific hot iron consumption rate of 950 kg/t and over, the slag formation process proceeds with deviations from the specified oxygen-lancing conditions under viscous slag formation during the converter turndown. Solutions are proposed to normalize the slag formation including dissolution of lime. This allows stabilizing of the slagging and lancing conditions, as well as preventing long downtimes of the equipment. [ABSTRACT FROM AUTHOR]

Leaching of 137Cs and 239+240Pu radionuclides with distilled and seawater from samples of radioactive slag from a ground-surface nuclear explosion on the coast of the Chernaya Bay of the Yuzhnyi Island of the Novaya Zemlya Archipelago, the Central Test Site of the Russian Federation, was studied in a laboratory. The 137Cs and 239+240Pu leach rate is ≤(2.7–3.5) × 10−6 and (4.8 ± 0.3) × 10−9 g cm−2 day−1 in contact with distilled water and (0.74–5.0) × 10−6 and (1.0 ± 0.14) × 10−8 g cm−2 day−1 in contact with seawater, respectively. [ABSTRACT FROM AUTHOR]

The microstructure of self-fluxing Ni – Cr – Si – B coatings formed on steel plates with the use of non-vacuum electron-beam cladding is studied. The effect of the structure and phase composition of the coatings on the level of their hardness is determined. [ABSTRACT FROM AUTHOR]

It is shown that the barium–strontium carbonatite can be used as a refining and gas-shielding addition for welding fluxes.Welding with the barium–strontium carbonatite reduces the degree of contamination of the welded joint with non-metallic inclusions: non-deformed silicates, spot oxides in brittle silicates, and also increases the desulfurization capacity of the welding fluxes. The addition of the barium–strontium carbonatite to the flux based on the slag of silicomanganese in the amount of up to 5% results in the formation of a ferritic–pearlitic structure of the metal of the welded joint with the Widmanstätten direction, with a small decrease of the grain size. The impact toughness and yield strength of the specimens increase as a result of adding the barium–strontium carbonatite to the flux, and the ductility properties and ultimate tensile strength of the samples decrease. [ABSTRACT FROM AUTHOR]

The protective properties of a newly developed phosphoric acidbased rust converter are investigated for reinforcement corrosion under chloride-contaminated concrete environment. The electrochemical evaluation of specimens after 6 years (2 years of wet-dry exposure in 3.5% sodium chloride solution and 4 years in dry laboratory environment) demonstrated that treating the reinforcing bar with the newly developed product significantly reduced the corrosion rate compared to the control reinforcing bar. Based on the results of Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy, a new mechanism is described for the transformation of unstable rust phases into stable phases. It is observed that iron phosphate remains entrapped with corrosion products formed on the surface of the treated steel reinforcing bar, even after 6 years of exposure. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental studies on how electrolysis borating and the steel grade of hardenable parts affects the boron and carbon distribution in the bulk of the diffusion layer. The structure, phase composition, boron and carbon concentration over the thickness of the hardened layer, and boride coating properties are examined. The optimal values of the initial carbon concentration are obtained. The optimal technological modes of the hardening process are determined, which makes it possible to develop a surface with minimum wear rate in abrasive environments. [ABSTRACT FROM AUTHOR]

Application of the most promising surfacing material — discrete filler — makes a significant difference in the processes of surfacing with current-supplying mould. Influence of electric parameters of surfacing on angular speed of slag pool rotation at application of three commercial flux grades was studied. It is found that ANF-29 flux allows producing a sufficiently large rotational effect both during the period of slag pool formation, and during surfacing. ANF-32 flux is less effective during the period of slag pool formation. AN-26 flux provides active rotation of the slag pool during surfacing, but this requires applying higher electric power to the pool. Angular speed of slag pool rotation is affected both by electric power applied to the slag pool, and surfacing current, but the latter has a determinant influence. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigations of the influence of rare-earth metal fluorides on structural changes in weld metal of titanium alloy VT22 for the purpose of using them in the flux filler of experimental flux-cored wire for welding this alloy. It was shown that refinement of b-grains is observed in welds made by argon-arc welding of VT22 alloy over a layer of flux, consisting of rare-earth metal fluorides. Addition of LaF3 to the core of experimental fluxcored titanium wire PPT-22 in combination with heat treatment allowed increasing the impact toughness of welds in argon-arc welding of VT22 alloy 2 times up to 30.6 J/cm2. [ABSTRACT FROM AUTHOR]

The lining of oxygen converters is a structural component, which requires permanent attention and significant investments in all metallurgical plants. These investments are connected with the necessity of application of high-cost refractory materials and with the expenses spent for the repairs of lining and relining, which strongly affects the cost of melting of steel. In this connection, in recent years, the metallurgical works all over the world try to find new efficient constructive solutions and improve the already existing technologies. One of these solutions is called the residual slag splashing technology. [ABSTRACT FROM AUTHOR]

Applicability of fluxes of different grades at electroslag surfacing of end faces by discrete filler material in a current- supplying mould was studied. It is found that selection of fluxes proceeding just from their physical properties (viscosity and electrical conductivity) does not guarantee the conditions required for conducting the electroslag process. Optimum position of the billet end face to be surfaced in the mould working cavity is very important for normal operation of the mould and performance of sound surfacing with good formation of the deposited metal. In view of the above-said, ANF-29, ANF-32, ANF-26 fluxes can be used for electroslag surfacing with discrete material. [ABSTRACT FROM AUTHOR]

For welding of dissimilar joints, the high-alloy welding materials are widely used. It is shown that the use of shielded arc mechanized welding method of dissimilar austenitic and pearlitic steels is limited due to formation of defects in the austenitic multilayer weld, such as lacks of fusion and lacks of penetration caused by appearance of a refractory oxide crust on the deposited metal surface. It is possible to increase the weld quality by providing its self-separation from the metal surface in the process of cooling. This is achieved by presence of a high content of such elements as silicon, titanium, zirconium, etc. in the welding wire, which reduce the amount of spinels based on chromium, nickel, molybdenum and others in the composition of oxide crust and increase the amount of brittle glassy phase. 15 Ref., 3 Tables, 1 Figure. [ABSTRACT FROM AUTHOR]

This paper considers the application of the method o f acoustic emission (AE) for the control of welding quality in process o f its manufacturing. Features AE method to detect in real time defects of weld joint during manual submerged arc welding and in cooling were studied. Set of informative AE parameters after the analysis of AE-monitoring and data o f arbitration methods of nondestructive testing was offered, which form a space of criteria for separating the signals from defects and interference that accompany the welding process. Determination o f the coordinates o f defects with high precision makes it possible to correct them in the operative welding process with a minimum of metal excision; reduces the volume of application of traditional testing methods. [ABSTRACT FROM AUTHOR]

The E.O. Paton Electric Welding Institute together with the E.O. Paton Chinese-Ukrainian Institute of Welding and the SPC «PLAZER» developed the equipment and technology for anticorrosion electroslag surfacing applying strips. The effect of current, voltage and surfacing speed as well as the gap between the strips on the stability of electroslag process, geometric dimensions of deposited beads and volume of base metal in the deposited one were investigated. In the experiments the stainless strips ESAB 309LNb ESW with the cross-section of 0.5×60 mm and the flux ESAB OK 10.10 were used. The range of surfacing modes applying two strips was determined, providing a high efficiency and a stable electroslag process with a good formation of deposited metal and a minimal penetration of the base one in the ranges of 7-9 %: Is = 1400-1500 A; Us = 32-33 V; vs = 14-17 m/h; the gap between the strips is 16 mm. The mechanical properties of the metal deposited at these modes applying the strips ESAB 309LNb ESW under the flux ESAB OK 10.10 are at the level of mechanical properties of steel 309LNb. The obtained results can be used in selection or development of materials and technologies for anticorrosion surfacing of parts of power and chemical equipment. 7 Ref., 1 Table, 6 Figures. [ABSTRACT FROM AUTHOR]

This article discusses the possibility of introducing nanosized particles into a molten pool using a flux-cored wire. A flux-cored wire has been proposed with added composite granules obtained upon the combined treatment of nickel powder and nanosized particles. In order to avoid the overheating of particles, it has been proposed to add a flux-cored wire to a molten-pool tail using preheating. The following hard- melting particles have been tested: tungsten carbide (WC), titanium nitride (TiN), and aluminum oxide (Al2O3). It has been demonstrated that the addition of tungsten carbide to a molten pool improves the stability of weld-metal (WM) impact toughness while retaining its average value and the addition of aluminum oxide to a molten pool leads to increased average values of WM impact toughness while retaining its stability. Meanwhile, nanosized particles of titanium nitride in a molten pool are prone to dissociation, which leads to the formation of porosity, thus limiting the field of application of this modifier. [ABSTRACT FROM AUTHOR]

The circulation and accumulation of harmful elements in blast furnace were investigated. The results show that the maximum concentration of K and Na in the belly is about 50 times of that in the charge. The zinc increased by 80 times and the Pb is insignificant. The impact of the circulation and accumulation of K, Na, Pb and Zn on the fuel consumption was quantitatively analyzed using Rist diagram. The results show that the gas utilization decreased and the coke rate increased linearly with the increase of load and accumulation times of each harmful element. Given the accumulation times of each element, the loading of Na, K, Zn and Pb into BF leads to the increase of coke rate by 13.99 kg/tHM, 6.25 kg/tHM, 3.63 kg/tHM and 0.02 kg/tHM, respectively. The increased coke rate and the decreased gas utilization under various loads and accumulation times of each element was estimated. [ABSTRACT FROM AUTHOR]

In 1950–1980 PWI laid the scientific foundations of development of fluxes for welding and melting titanium and its alloys. Technology of automatic consumable electrode welding of titanium with application of oxygen-free fluxes was developed. Processes of tungsten electrode argon-arc welding over a layer of flux (TIG-F) and tungsten electrode welding with application of titanium flux-cored wire (TIG-FW) were developed. These methods expand the technological capabilities of tungsten electrode arc welding, provide high quality of titanium welded joints and guarantee absence of pores in welds. [ABSTRACT FROM AUTHOR]

The article offers information on the Ukrainian company TM Veltek Ltd. and its manufacture of flux-cored wires. It mentions the firm's implementation of engineering measures toward the repair and advancement of its equipment especially for production lines and technological optimization of making the wires. It also notes its development of surfacing and welding flux-cored wires in various sizes as well as financial support to medicine and sports.