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Refractory lining is an integral part of metallurgical facilities and requires constant perfection. Examples of successful interaction of specialists-steelmakers, companies-manufacturers of refractories and engineering companies on increasing efficiency of refractories application in steel industry presented. The wide application of drying and heating stations of steel ladles, EAFs, BOFs was noted because of using refractory gunned castable at their current repairs. The growth of unmolded refractory share in the BF production was shown. At the stoves repair technology of guniting and shotcreting is widely used. Transfer to application of modern concrete at lining of shoots, ramming mixtures and repairs with application of liquid concrete addition resulted in a decrease of labor­ intensiveness of repair work, accelerated the process of repair and considerably decreased specific consumption of refractory materi­als. Nevertheless, within a predictable period, despite of increase of unmolded refractories application, it is expected that the molded refractories would take the main share of the refractory market in the steelmaking. Creation of partial load conditions in a metallurgical facility is an important factor for increasing lining resistivity. Slag foaming in EAF screens radiation from electrodes in the process of the furnace running. Blowing of the final slag (preliminary enriched by magnesium oxide in case of necessity) forms a scull on the working surface of the BOF lining, thus preventing intensive contact of the refractory lining with steel melt and slag. Modem technologies of instrumental control the lining state of metallurgical facility within the period of its running considered, which allowto accomplish operation of hot repair at particular arears of the lining, avoiding overconsumption of the repair material. It was noted that apart from the task of decreasing specific expenses for refractory materials, the customers most often estimate the indirect costs, cover of loss and obtaining additional profit due to increase of metal production because of increase of overhaul period and decrease of time of lining repair. This is the purpose of cooperation of specialists of refractories manufacturers and metallurgical plants.

The article presents the results of a comprehensive study of the modes of laser processing during the formation of a coating on nickel-aluminum bronze using nickel powders. The coating was obtained in two stages. At the first stage, a precursor coating of the powder material was applied by cold spraying, at the second stage, its surface treatment with a laser was performed. The change in the composition and properties of the coating is shown depending on the processing modes and the thickness of the precursor coating, as well as the modes of laser processing.

In the automotive industry there is an increasing demand for the wider application of high strength steels due to their favourable mechanical properties. The steel producers continuously developing new generations of high strength steels to insure higher strength and toughness properties. Since in most cases these steels are joined in welded structures, great attention must be taken to their weldability. The weldability of high strength steels has still challenges which are as follows: cold cracking sensitivity; reduction of strength and toughness of heat affected zone (HAZ); filler metal selection. Because the mechanical properties of ultrahigh strength steels are provided by using various alloying elements, micro alloys, and by different metallurgical methods, the steels may lose their outstanding properties during welding. In real welded joints the critical parts of the HAZ have small extent so their properties can be limitedly analysed by conventional material testing methods. With the help of physical simulators, the different parts of the heat affected zone can be produced in an adequate size for subsequent tests. In our research work the weldability, especially the HAZ properties of an ultrahigh strength structural steel (Rp0.2 = 1300 MPa) were investigated on thermal simulated samples with the help of Gleeble 3500 physical simulator. Three relevant technological variants for gas metal arc welding (GMAW), t8/5 = 5 s, 15 s and 30 s were applied during the HAZ simulations in the selected coarse-grained (CGHAZ), intercritical (ICHAZ) and intercritically reheated coarse-grained (ICCGHAZ) zones. Both the microstructure was studied by optical microscope and the mechanical properties were analysed by Vickers hardness tests and Charpy V-notch impact tests at -40 °C. According to the results the investigated ultrahigh strength steel was softened on account of the welding heat cycles, besides that the strength of the investigated ultrahigh strength steel can be better with the application of shorter t8/5 cooling time.

Mechanical characteristics of an alloy, used for manufacturing parts of heavy-duty machines, operating under conditions of dynamic and cyclic loads, should meet increased requirements. According to the concept of lean alloying, quality of an alloy and highest possible properties of a chemical composition are determined by the modes of heat treatment. Results of a study of quenching temperature effect on microstructure and properties of a new lean alloyed steel MAGSTRONG 450L having the following chemical composition, %, mass: 0.21 С; 0.23 Si; 0.96 Mn; 0.03 Cr; 0.41 Ni; 0.023 Ti; 0.0021 B presented. Smelting of ingots of a given chemical composition was carried out in a vacuum induction furnace ZG-0.06L. Reduction of ingots was carried out on a hydraulic press П6334 and on a single-stand reversing hot rolling mill 500 duo. The samples were heated in a ПКМ 3.6.2/12,5 chamber furnace. Best mode of the hardening heat treatment of sheet rolled product of steel MAGSTRONG H450L was established, ensuring forming of a mixed structure, comprising 80% of lath martensite and about 20% of high temperature lamellar martensite. Such a structure ensures maximum values of impact toughness KCV–40 = 38 J/сm2 at high strength parameters (tensile strength σв = 1514 МPa, offset yield strength σ0,2 = 1243 МPа, hardness 460 HBW) and satisfactory indices of plasticity (percent elongation δ50 = 16 %) which correspondents to requirements ТС 14-101-1034–2015. Based on results obtained, recommendations were elaborated for heat treatment of the sheet steel MAGSTRONG H450L, thickness 8–20 mm as per OJSC “BELAZ” order. Application of the obtained results of the study will enable to create and perfect the technological modes of heat treatment of alloys with similar composition.

Significant cost and time savings may be realised if multiple weld repairs are undertaken at the same location during the long-term maintenance of naval vessels. Consequently, this investigation simulates full-thickness hull welds, which are required to facilitate the removal and subsequent replacement of hull sections, by assessing the effects of 4 reoccurring weld repairs on a propriety quenched and tempered steel used for naval applications. Optical metallography, electron backscattering diffraction (EBSD), hardness maps, Charpy impact, and dynamic tear tests were conducted. A combination of real weld repairs and Gleeble heat-affected zone (HAZ) simulations were undertaken to characterise the effects of repeated thermal cycles on the microstructure and toughness of different sub-HAZ regions. When the intercritical reheat temperature was just above the AC1 lower critical transformation temperature, the impact toughness was substantially reduced. This includes the fine-grained HAZ where high toughness is typically expected. The low toughness was attributed to the promotion of fracture initiation via debonding between the matrix and second phase which formed at prior austenite grain boundaries. Compared to the original toughness, the application of multiple repeat welds or multiple simulations of the same sub-HAZ thermal cycle did not deteriorate toughness nor noticeably alter the final microstructure.

This study aims to evaluate the weldability of dissimilar welds with the Inconel 625 and the Hastelloy C-276 nickel-based alloys deposited on ASTM A36 and AISI 1045 carbon steel plates. The welds were carried out by the GMAW process and evaluated by the Trans-Varestraint test. The test results were statistically evaluated, and Fusion Zone solidification processes were simulated in JMatPro software using several dilution levels. The analysis of variance (ANOVA) test results showed that the two different base metals did not affect the weldability of Inconel 625. However, the Hastelloy C-276 alloy showed a significant drop in weldability with the AISI 1045 steel compared to the ASTM A36. The results of the Hastelloy C-276 as the filler metal and the AISI 1045 steel as the base metal showed greater susceptibility to solidification cracking than all the other pairs tested, according to the Trans-Varestraint test. Moreover, the ANOVA test results indicated that the different heat input levels did not influence the sets’ weldability; this was probably because there was only a tiny variation in the dilution levels. The solidification process simulation indicates that higher dilution levels promote the precipitation of a larger secondary phase fraction.

A novel magnesium (Mg) production process utilizing an electrolytic method was investigated for the direct reduction of magnesium oxide (MgO). Electrolysis of MgO was carried out with an applied voltage of 3.0 V using a copper (Cu), silver (Ag), or tin (Sn) cathode and carbon (C) or platinum (Pt) anode in magnesium fluoride (MgF2)−calcium fluoride (CaF2)−sodium fluoride (NaF) at 1273 K or MgF2− lithium fluoride (LiF) at 1083−1093 K. After the electrolysis of MgO in MgF2−CaF2−NaF molten salt, Mg alloys such as Mg2Cu, Cu2Mg, or Mg2Sn phases were produced with current efficiencies of 75.8−85.6% when the concentration of Mg in Mg alloys was 9.1−14.6 mass%. In addition, when the electrolysis of MgO was conducted in MgF2–LiF molten salt, Mg alloys such as Mg2Cu or AgMg phase were produced with current efficiencies of 76.2−81.7% when the concentration of Mg in the Mg alloys was 12.5−13.2 mass%. In addition, to produce high-purity Mg metal from Mg alloys, vacuum distillation was conducted. When vacuum distillation was conducted at 1100−1400 K for a duration of 5 h, the concentration of Mg in the Mg alloys feed decreased from 30.2−34.1 mass% to 0.64−1.75 mass%, and Mg metal with a purity of 99.998−99.999% was obtained under certain conditions. Therefore, the molten salt electrolysis using liquid metal cathode (MSE-LMC) process developed here is feasible for the direct reduction of MgO using an effective and environmentally sound method.

The process of enrichment of potash ore using industrial oils as a hydrophobizing agent in the collective mixture of potassium chloride, which is a composition of salts of higher aliphatic amines, pine oil and polyethylene glycol PEG- 400, has been investigated. A comparative analysis of the influence of industrial oils I-8A, I-12A, I-30A and liquid paraffins on the technological parameters of potash ore flotation has been carried out. The influence of hydrophobizing additives on the adsorption of amine on potassium chloride crystals was investigated by infrared spectroscopy. It has been established that the introduction of industrial oils into the flotation system ensures the recovery of potassium chloride at the same level as when using a collective mixture with liquid paraffins. The best flotation performance when using industrial oils is possible by increasing the consumption of the apolar reagent.

Purposeful control of structural state of steel at every stage of technological chain of steel goods production is necessary for elaboration of effective metallurgical technologies. The purpose of the complex of research and theoretical studies was development of ideas on peculiarities of structure formation of various steel grades. Current conceptions about phase and structural transformations in steels with different contents of carbon and alloying elements considered. For carbon and alloyed steels, the results of the study of the structure of perlite formed at different temperatures summarized; morphology, crystallography and defects of crystalline structure of cementite, processes of its fragmentation, coagulation and spheroidization; crystallography of austenite degradation products; evolution of the structure during cold and hot plastic deformation; carbon redistribution processes prior to and during diffusion-controlled austenite decay presented. For low-carbon low-and sparingly alloyed cold-resistant weldable steels generalized results of investigation of structure-formation processes, alloying relationships, temperature-deformation rolling conditions, parameters of quenching and high-temperature tempering with structure, mechanical properties and performance characteristics of steel plates presented. The elaborated complex of scientific and technical solutions based on the studies enabled to master and digitize production technologies at PJSC “Magnitogorsk steel-works” of new generation steel rolled products intended for ship-building, oil and gas industries, automobile, hardware and construction industries. The new systems of alloying steels of various application, methods of the new generation steels production and automated control of technological processes protected by 27 patents of RF, are widely used in the production activity of PJSC “Magnitogorsk steel-works”.

The present study was carried out to investigate the effects of Ni and Zr additions, individually or in combination, on the room-temperature tensile properties of 354 casting alloy (Al–9wt%Si–1.8wt%Cu–0.5wt%Mg) which was isothermally treated at temperatures in the range of 155–350 °C and aging times up to 1000 h. Tensile tests were carried out in the as-cast, solution heat-treated, and aged conditions using different aging times up to 1000 h. Quality charts were used as an evaluation tool for selecting the optimum conditions to achieve superior tensile properties and optimum quality in 354-type alloys. Zirconium reacts only with Ti, Si, and Al to form (Al,Si)2(Zr,Ti), (Al,Si)3(Zr,Ti), and Al3Zr phases. The beneficial effects of Zr and Ti additions appear in the refining of the α-Al grain size which reduces the size of the Al2Cu and α-Fe particles. Tensile test results at ambient temperature show a slight increase in alloys with Zr and Zr/Ni additions, particularly at aging temperatures above 240 oC. It is suggested that the maximum obtainable quality index values by means of heat treatment are the difference between the quality index values for the as-cast and solution heat treatment conditions.

This research studied the electrochemical corrosion behavior in 1 M hydrochloric acid of a Fe-Cr-Mo-B-C alloy fabricated using spark plasma sintering of an amorphous alloy starting powder. The corrosion performance was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization tests and was benchmarked with conventional materials: 316L stainless steel and 1080 carbon steel. The corrosion reaction products on the surface were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy and energy-dispersive spectroscopy. The specimen sintered at 800 °C had approximately 94% densification, whereas the specimen sintered at 900 °C exhibited greater densification of approximately 98%. The sintered specimens consisted of nanocrystalline (Fe,Cr)23C6 and (Cr,Fe)2B particles embedded in a body-centered-cubic Fe-based matrix. These sintered specimens exhibited better corrosion resistance than conventional alloys. When the density of the sintered alloy decreased from 98 to 94%, resistance to chloride attack was increased because of the formation of a thicker and more uniform surface product as well as a chromium-containing oxide layer.

Cu–6.5% Al alloys and Cu–6.5% Al alloys containing small amounts of silicon (Si) and manganese (Mn) were deposited using wire arc additive manufacturing (WAAM) by feeding two different components of wires simultaneously into the molten pool. The deposited alloys were homogenized by heat treatments at 800 °C (2 h). The effect of addition of Si and Mn on the microstructure and mechanical properties of Cu–6.5% Al alloys were investigated. Microstructural and formation of intermetallic compounds were studied. Results revealed that upon heat treatment, Si and Mn were able to restrain the dislocation movement due to the formation of second-phase particles. When compared to Cu–Al alloys, mechanical testing of the Cu–6.5% Al alloys having Si and Mn showed that hardness had increased by120 Hv, ultimate tensile strength (UTS) had increased by 284 MPa and yield strength (YS) had increased by 365 MPa, whereas its elongation (EL) had decreased by 22%.

The aim was to investigate the chemical composition of refinery slag obtained during silicon production in order to identify approaches to its further recycling. Research samples were collected from the slag remained after oxidation refining at the JSC Silicon (AO Kremny), RUSAL (Shelekhov, Irkutsk Oblast). The methods of X-ray phase, X-ray fluorescence, metallographic and scanning electron microscopy were employed to investigate the chemical composition of the samples. It was found that the refinery slag under study includes such basic components as elemental silicon, its carbide and oxide, as well as elemental carbon. It was shown that silicon carbide is the product of incomplete reduction, resulting from melting silica-containing ores in a smelting furnace. According to the conducted X-ray fluorescent analysis, the samples also contain (wt %): Ca - 7.40; Al - 3.80; Fe - 0.30; Ba - 0.19; K - 0.14; Na - 0.09; Sr - 0.09; Mg - 0.08; Ti - 0.05; S - 0.02. Calcium and aluminium are present in the slag mostly in the form of oxides. Complex oxides of an anor-thite type were also found: CaO Al2O3 2SiO2. The refinery slag under study also features insignificant amounts of other metal oxides, which are released from the furnace slag forming during the smelting process. The slag produced by oxidation refining during crystalline silicon production is a technogenic raw material containing valuable components. Due to the significant content of silicon in the refinery slag (from 42% to 65%), the existing methods applied to recycle such an industrial material were analysed in terms of additional silicon extraction or production of commercial silicon-containing products, which are in demand in various industries.

The possibility of raising the impact toughness of medium-manganese TRIP-steel Fe – 0.2% C – 6% Mn – 3% Al by application of a novel heat treatment involving quenching from the intercritical temperature range and subsequent tempering is investigated. Electron microscope and x-ray diffraction studies are performed after the heat treatment. The quenching mode providing the highest impact toughness is determined.

The influence of the initial structure on formation of austenite, evolution of structure, and elevation of operating characteristics of steel SA508 Gr.3 (0.24% C, 1.40% Mn, 0.88% Ni, 0.54% Mo) after an intercritical heat treatment (IHT) is studied. After the IHT, the grain size of the hypoeutectoid ferrite in the steel with an initially ferritic-bainitic structure is much larger than in the initially bainitic or martensitic structures. The density of the low-angle and high-angle boundaries is much higher in the steel with initial bainitic or martensitic microstructure. The initial microstructure affects substantially the strength and the impact toughness of the steel subjected to IHT. The mechanical properties are increased as a result of refinement of the microstructure and growth of the density of grain boundaries.

This paper deals with three types of triplex steel, where containing 25 to 28 wt.% manganese, 0.8 to 0.89 wt.% Carbon, 9.9 to 11.11 wt.% Aluminum, and with different Nickel content. Two types contain Ni in range of 0.9 to 2 wt.% and third type doesn’t contain Ni. The precipitation of Nano-size kappa carbides is the most proper technique used for this objective. It is expected that inter-metallic strengthening mechanism should act more effective in promoting the strength of Triplex steel with ductility. From this point of view, this research was designed to study the effect of inter-metallic inductive alloying element as Nickel on promoting of the strength and ductility of the high aluminum containing high manganese steel. Optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to detect of inter-metallic precipitates through steel investigated ranged in Nickel from 0 to 2 wt.%. Mechanical and strain hardening properties were determined in the steel investigated after different regimes of heat treatment. It was found that Ni3Al inter-metallic compound provides the austenite matrix with good strength and ductility, depending on the ageing time. Further deterioration was obviously observed in the steel investigated as increasing the ageing time, attributing to coarse structure occurrence.

The results of investigations of the features of the behavior of the components of mixtures of refractory carbide powders with metals during explosive pressing are presented. It is shown that the main factor determining the compaction of mixtures is the dynamic flow of one of the phase components of the mixture into the initial pores of the powder. As the phase component of the mixture, the movement of which limits the degree of compaction and leads to the formation of a continuous matrix in the structure of the material pressed by the explosion, both the metal binder and the carbide component of the material can act.

The results of a study of the wear resistance of coatings based on cuprides of titaniumin the temperature range of 20-600 С are presented. It is shown that the wear resistance of nickel-doped coatings exceeds the wear resistance of binary coatings. With an increase in the Ni content of more than 10 %, their resistance to wear increases slightly.

Carbon steels can be sensitive to solidification cracking. Predicting their susceptibility to solidification cracking can save cost and time compared to testing, and it can be very useful for designing new steels or welds. Crack susceptibility predictions were made for carbon steels using the recently proposed simple susceptibility index for cracking during solidification, maximum │dT/d(fS)1/2│ near the end of solidification (T temperature and fs fraction solid). T vs. (fS)1/2 curves of the carbon steels were calculated by three different solidification models: equilibrium, Scheil, and Scheil with back diffusion of the available commercial thermodynamic software. The crack susceptibility predictions based on these solidification models were compared to various crack susceptibility test results of carbon steels, and the predictions based on Scheil with back diffusion were found consistent with the most of the crack susceptibility test results. Solidification temperature ranges of the carbon steels, determined based on the solidification models of equilibrium, Scheil, and Scheil with back diffusion, were used to explain the crack susceptibility predictions. The role of the alloying elements of the carbon steels in solidification cracking susceptibility was discussed.

MARBN alloys, which are anticipated an estimated 25 °C increase in advanced ultra-super critical (A-USC) power plant operating temperature, are expected to be commercially available soon and will partially displace some older materials and lead the market. Two examples are the Japanese alloy, 9Cr-3W-3Co-Nd-B material, which is considered a strong contender in wrought pipework, and the UK’s IBN-1 alloy which currently leads the development in cast steels. Through the courses of two consecutive UK collaborative projects IMPEL and IMPULSE, a matching composition filler metal for welding MARBN alloys in the form of shielded metal arc SMAW electrode has been developed. The design of this filler metal was aimed to optimize the deposit chemical composition hence to provide creep resistance properties matching the base alloys. The weld metal was specifically intended for high integrity structural service at expected temperatures. Accordingly, the minor alloy additions responsible for its creep properties were kept at the middle of the base alloys or at least above the minimum considered necessary to ensure a satisfactory performance. This paper introduces the design, investigation and test results of the matching filler metal. Findings relevant to the microstructure, mechanical properties at ambient and elevated temperatures, including creep properties of the all-weld metal and weld joint made with IBN-1 base alloy, are presented.

Hot tearing is a common solidification defect in both continuous cast steels and foundry shaped castings, which has a significant impact on the quality of the final products. It is a complex phenomenon that involves both the thermal and mechanical conditions and chemical element segregation that evolves during casting process. Over several decades, much effort has been invested into improving our understanding of the conditions required for the occurrence of hot tearing and to relate these conditions with casting parameters, like casting speed in continuous cast process, alloy composition, cooling conditions, etc. This review summarizes the results from previous investigations that have focused on the hot tearing phenomenon of steels, including criteria for hot tearing, experimental methods, and several validated models for different testing methods. The factors that influence hot tearing sensitivity are also reviewed and discussed in the present work.

On the basis of studying the effect of rare earth elements on hot tearing susceptibility (HTS) of Mg–Zn alloys, further exploring effective ways to reduce HTS of Mg–Zn–Y alloys are very important for the development and application of magnesium alloys. In this paper, the effects of 2 at% Y on HTS of MgZn1 alloy and several grain refiners on HTS of MgZn1Y2 alloy were studied. The modified Clyne–Davies model is used to predict the HTS of the investigated alloys, which are found in the descending order: MgZn1 > MgZn1Y2 > MgZn1Y2–0.5 wt% Na2CO3 > MgZn1Y2–0.5 wt% Ti > MgZn1Y2–0.5 wt% Zr. By means of XRD, SEM, TEM and EBSD, the evolution of the microstructure during solidification is revealed. The results show that the addition of 2 at% Y can not refine α-Mg grains, but it can change the precipitation type of the second phase. When the precipitation type of the second phase changes from Mg7Zn3 to Mg12ZnY (LPSO phase) and Mg3Zn3Y2 (W-phase), the solidification end temperature of the alloy increases by more than 100 °C, and the coherent lattice of LPSO and α-Mg has a better bridging effect on the grain boundary, which reduces the HTS by 28.4%. Moreover, the addition of 0.5 wt% Na2CO3, 0.5 wt% Ti or 0.5 wt% Zr is an effective method for α-Mg grain refinement, equiaxation and dendrite coherent delay of MgZn1Y2 alloy. In particular, the addition of 0.5 wt% Zr can reduce the α-Mg grain size of MgZn1Y2 alloy by 89.1% and increase the solid fraction by 45% when dendrites are coherent, which results in a 77.1% reduction in HTS.

The article presents the study of the nature of dust and smoke generation during gas-oxygen blasting of a converter bath. The main reasons causing metal waste have been determined. Influence of the process main parameters on metal loss has been studied during dust removal and evaporation of iron in the reaction zone. The authors have estimated the process of metal pulverization due to CO bubbles floating, determined by the rate of their rise to the bath surface. Specifics of temperature regime of the reaction zone and heat balance have been determined when adding fuel to the oxygen flow. Adding fuel to oxygen makes it possible to increase heat input into the bath, while reducing the rate of decarburization. This enables reduction of dust discharge during rupture and crush of metal films by gas bubbles. The effect of combustion products oxygen use on metal impurities oxidation is considered. By the example of blasting carbon and alloyed steel for mill rolls, it has been shown that the degrees of CO2 and H2O decomposition in the bath are the main qualities of gas-oxygen blasting. These indicators determine the oxidizing and heating properties of the blast. Assessment of change in total, consumed heat and its losses with exhaust gases, depending on degree of the oxygen flow dilution with natural gas (methane), has been carried out. Under these conditions, use of submersible combustion torches with change in their oxidizing ability makes it possible to solve various technological tasks, including provision of an effective way to reduce dust emission in converter process.

The empirical equation to predict the heat-affected zone (HAZ) hardness of B-added steels has been proposed. For this purpose, weld thermal cycle simulation tests of both B-free and B-added steels in combination with hardness measurements were conducted. Firstly the previous HAZ hardness prediction equation was modified using the experimental results of B-free steels. Next, by introducing the B effect on hardenability to the modified equation, a new empirical equation to predict HAZ hardness of B-added steels was developed. The present equation takes into account the effects of peak temperature and Mo composition on B hardenability. The comparison of the predictions with the experiments of the weld thermal cycle simulation tests showed that the present equation can predict the HAZ hardness fairly well. The adjustable parameters of the B effect on hardenability introduced to the equation agree with the conventional results in the literature. To confirm that the present equation can be used to predict HAZ hardness of actual welded joints, hardness profile of welded joints was measured. The predicted HAZ hardness profile has shown to be in good accordance with the measured hardness profile.

The article examines a number of regularities in the production of primary cast ingots of AlSi7Mg, AlSi7MgSr, AlSi11Mg, and AlSi11MgSr. Peculiarities of melting and cast of these alloys, as well as the effect silicon and strontium have on the formation of the shrinkage cavities, have been explored. It has been demonstrated that strontium, when used as a modifier, changes not only the morphology of silicon, but also the nature of solidification and shrinkage of the alloy. Defects formed in the ingots manufactured from near – eutectic AlSi11MgSr alloy have been studied in greater detail.

This work presents studies on the material composition and physico-mechanical characteristics of an alumina-containing estimate formed during the production of aluminum on electrolyzers with self-baking anodes during technological operations. The material is a mixture of fine powder 2.5 mm in size (62.78% on average mass) with the presence of pieces of material ranging in size from 0.5 to 6 cm (average 20.26% by weight). The samples contain pieces of hardened aluminum with sizes from 5 to 20 mm (16.96%). The largest content in the sample has the fineness classes-0.315 + 0.16 mm in the volume of 29.85% and the largest class +2.5 mm-37.22%. B It was established that aluminum is concentrated in the fractions-0.315 + 0.16 mm (45.7%) and 0.16 + 0 mm (48.8%), silicon in the fraction-0.63 + 0.315 mm (1.91%), iron at-1.25 + 0.63 mm (0.601%) and-0.63 + 0.315 mm (0.62%). The material consists of cryolite (Na3AlF6), chiolite (Al3F14Na5), quartz, feldspar, carbonaceous matter and the technogenic phase of the composition (NaF) 1.5CaF2 AlF3. The material is characterized as non-abrasive (working index Ai - 0.0184) and very soft in relation to impact crushing (working index CWi - 3.64), the working index of ball grinding Bond (BWi - 6.47) characterizes a very low resistance to ball grinding. The implementation of the crushing operation of an alumina-containing estimate will allow the use of dry cascade-gravity and centrifugal classification to separate impurities in the form of SiO2, and Fe2O3 for the use of alumina-containing material in primary aluminum technology. On the basis of laboratory tests, it is established that alumina-containing raw materials can be separated and photometric and gravitational separation methods can be used. A mathematical model of the motion of particles of primary and prepared alumina-containing raw materials in a cascade-gravity classifier was developed. The criteria and factors characterizing the alumina-containing material, as well as influencing and determining the maximum material enrichment, are established.

The article is devoted to the study of destructibility of the annealed anode paste of different composition in the CO2 current. It is shown that the destructibility of CO2 current of petroleum coke is much less than that of pitch coke. The comparison of the qualitative characteristics of the anode paste on the basis of pitch coke and petroleum coke revealed the advantage of petroleum coke, due to its low sodium content. The average destructibility of the anode paste on the basis of different grades of cokes in the CO2 current is determined. The conducted semi-industrial tests were in good agreement with the laboratory studies.

During this research work, the impact toughness and tensile strength of the electron beam-welded AISI409 plates were evaluated as a function of varied heat input (low 0.96 kJ/mm and high 1.10 kJ/mm) and after imparting post-weld heat treatment. Ferritic stainless steels are prone to enlargement in grain structure and degradation of mechanical properties on exposure to heating and cooling cycles during welding which results in deterioration in their performance. Results revealed that the base metal possessed coarse ferrite grains which got transferred into columnar and axial grains due to faster cooling rate of electron beam welding. The impact toughness of the specimens extracted from the top region of weld zone, when welded using high heat input, reduced by 46% as compared to the base metal. However, the specimens extracted from the bottom section possessed 83% higher impact toughness as compared to the top section. Further, the post-weld heat treatment resulted in refined microstructure, which increased the impact toughness by 35% and 24% for high heat input and low heat input welded joints, respectively. However, the tensile strength of the specimens extracted from the bottom section improved by 26% as compared to the base metal.

The effect of single pass and multipass (double and triple pass) gas metal arc welding (GMAW) on the microstructure and stress corrosion cracking susceptibility of Al5083-H321 alloy was studied. For this purpose, ER5183 filler metal was used. The results indicated that the weld metal exhibited a dendritic structure which was refined with the increase in the number of passes. Also, it was found that the weld fabricated by two passes exhibited the best stress corrosion cracking (SCC) resistance. The results of the SCC tests also revealed that although the double pass sample had the higher ultimate tensile stress value of about 310.8 MPa among weldments, it was still lower than that of the base metal (BM), which had the ultimate tensile stress of about 366.5 MPa.

Aluminum is widely used in various industries in the form of alloys due to its unique properties - lightness, high electrical conductivity, and corrosion resistance. However, when casting alloys, various defects arise, the main of which are nonconformities of the ingot chemical composition, mechanical properties, and internal structure. The RUSAL Bratsk PJSC (, Irkutsk Region) aluminum alloy samples have been examined for pores, cracks, and oxide films. The causes of their occurrence have been analyzed and ways to eliminate these defects proposed. It has been found that, with increasing hydrogen content in the melt, micro-porosity leads to friability and macro-porosity of the alloy structure. According to the study results, the likelihood of cracks in the ingots could be reduced by evenly decreased metal temperature and casting velocity. The oxide film defects have been eliminated by feeding metal into the mold in a steady turbulence-free manner, increasing the metal settling time in a mixer, and reducing the alloy preparation time in a furnace.

The article is devoted to the study of technological modes of hot rolling of tube steel on a thick-sheet mill and mechanical properties of the finished products. Five slabs were rolled under the experimental regime in accordance with the study plan. The temperature conditions of rolling at the final stage of deformation and the modes of accelerated cooling of rolled products were changed. Dependencies between technological parameters and mechanical properties allowed developing recommendations on improvement of technology of rolling and of the subsequent accelerated cooling of metal.

The article presents the test results of complex microcrystalline modifiers containing calcium, barium, strontium, rare earth metals. Complex modifiers were used in the processing of steel for 17G1S-U pipes in order to reduce its contamination with non-metallic inclusions, including corrosive ones. The use of modifiers allowed to reduce metal contamination by non-metallic inclusions of all kinds. The most experimental non-metallic inclusions were obtained during metal processing with INSTEEL®5.1 and INSTEEL®9.4 modifiers. In addition, the use of experienced modifiers ensured the production of complex oxysulfides of calcium, cerium and lanthanum with low oxygen content and thermal expansion coefficients, which increases the corrosion resistance of steel.

The microstructure of the advanced low carbon steel with a superior hardenability was studied. The steel contained the following main alloying elements, wt. %: C – 0.20; Cr – 2.0; Mn – 2.0; Si – 1.04 Ni – 1.0; Mo – 0.3. The dilatometer investigation of the steel under consideration revealed the only phase transformation occurring during continuous cooling (0.1...30 °C/s), which started at the martensite start temperature Ms. It was shown that the isothermal treatment of the studied steel led to the bainite formation above and below Ms. The temperature of the bainite morphology shift was determined.

In automotive industries, employing advanced high-strength steels such as dual-phase steels by taking advantage of high dynamic force absorption during car accidents and lightweight is one of the major challenges. In this regard, the effect of resistance spot welding parameters on the above great properties of advanced high-strength DP590 steel has been studied. In this study, the effect of optimized welding (spot resistance welding) on the weld microstructure was evaluated using optical microscopy as well as scanning electron microscope equipped with electron backscatter diffraction analysis (EBSD). Also, hardness profile along with the welding section was determined as mechanical property. The results showed that the welding practice has a significant influenced on the microstructure and microhardness of welded samples. The final microstructure of the nugget consisted of lath martensite, whereas in the HAZ, the microstructure was found to be mixture of coarse and fine martensite. The hardness profile was relevant to the above phase configuration. The phase variations along with different weld region were extensively characterized and discussed using EBSD technique.

The joining of plastics is required because component geometries are severely restricted in conventional manufacturing processes such as injection molding or extrusion. In addition to established processes such as hot plate welding, infrared welding, or vibration welding, hot gas butt welding is becoming more and more important industrially due to its advantages. The main benefits are the contactless heating process, the suitability for glass fiber reinforced, and high-temperature plastics as well as complex component geometries. However, various degradation phenomena can occur during the heating process used for economic reasons, due to the presence of oxygen in the air and to the high gas temperatures. In addition, the current patent situation suggests that welding with an oxidizing gas is not permissible depending on the material. On the other hand, however, there is experience from extrusion welding, with which long-term resistant weld seams can be produced using air. Investigations have shown that the same weld seam properties can be achieved with polypropylene using either air or nitrogen as the process gas. Experimental investigations have now been carried out on the suitability of different gases with regard to the weld seam quality when welding polyamides, which are generally regarded as more prone to oxidation. The results show that weld strengths are higher when nitrogen is used as process gas. However, equal weld strengths can be achieved with air and nitrogen when the material contains heat stabilizers.

This study aimed to investigate the heat-affected zone (HAZ) behavior in an API 5L X70 steel welded by the gas metal arc welding process (GMAW). In the steel welding processes, this region is very critical due to microstructural and allotropic transformations that affect the mechanical properties. Three samples were welded using a robotic arm with different welding speeds, thus obtaining three different heat inputs, which were 2.0 kJ/mm, 2.5 kJ/mm, and 3.0 kJ/mm. For all heat inputs, the microstructures of the HAZ showed the Widmanstatten ferrite, Acicular ferrite, bainite, and martensite and retained austenite, which influenced the mechanical properties of this region. The electron backscattering diffraction analysis showed that the presence of low-angle grain boundaries (2–15°) increases the fracture toughness. The kernel average misorientation map and the results of the Charpy impact test showed that the heat input of 3.0 kJ/mm lead to characteristics of the HAZ that are remarkably similar to the base metal (BM).

This paper documents a series of experimental 4130 heats that had additions of rare earth master alloys with different rare earth oxide inclusions. Once melted, the heats were poured into keel block castings for mechanical testing and metallographic examination. Additionally, a single-thermocouple thermal analysis system was employed to examine the solidification reactions of each heat. Several interesting observations were made. First, the mechanical properties and solidification structure of the heats were similar, contrary to earlier work in 4130. Thermal analysis noted that the liquidus and peritectic did not shift with the master alloy additions. Inclusion characterization found that the inclusions in the final castings were significantly different from the ones in the master alloys. These inclusions contained low or no sulfur in them. Based on this, the author concludes that sulfur-containing rare earth inclusions are the likely nuclei in steels. This work identifies several important factors in the grain refinement of 4130. Not all rare earth inclusions cause refinement, supporting the conclusion by many that specific rare earth inclusions refine a steel’s structure by acting as heterogeneous nuclei. Sulfur-containing inclusions may be the compounds that are acting in this role. Additionally, shifts in the peritectic temperature appear related to the occurrence of refinement. No refinement in this work occurred, and no peritectic shift happened either. Other work in the literature observed an increase in the peritectic temperature and the onset of refinement. The peritectic reaction appears to play a role in steel solidification refinement.

This research investigates the nickel content added by 1.1wt%, 2.2wt%, 3.7wt% and 4.5wt% on the microstructure and mechanical properties in the nodular cast iron. The results demonstrate that the microstructure of nickel addition consists of nodule graphite, ferrite and pearlite phase while nickel was added to 4.5 wt% the microstructure becomes ferrite transform to fully pearlite phase. In addition the ductile iron has the highest nodularity (0.79%), followed by 1.1%Ni (0.75%), 2.2%Ni (0.71%), 3.7%Ni (0.69%) and 4.5%Ni (0.58%). The hardness and tensile strength increase when increasing the nickel content. Elongation is enhanced with nickel increasing and reaches a maximum of 12% at 1.1 wt% Ni, then decreases with the further increase of nickel.

The main mechanisms of structure formation in zones of welded joints of unlike metals (steel – aluminum) obtained by friction stir welding in the mode of structural superplasticity are considered. Sheet billets of different steels (St3ps, 12Kh18N10T) and deformable aluminum alloys (AD1, AMg6) with a thickness of 3 mm are butt- and lap-welded by the friction stir technique. The microstructures, the phase components and the mechanical properties of the welded joints are determined.

The parameters of the process of production of flawless bimetallic billets from powder steel R6M5 (the external layer) and 5KhNM (the core) are assessed by mathematical simulation. The bimetal has mechanical properties comparable to those of cast and deformed high-speed steel, a more homogeneous structure, and a much lower cost.

The methods of transmission and scanning electron microscopy are used to study the evolution of the structure of a welded joint of steels 32G2 and 40KhN in the thermomechanically affected zone (TAZ) under rotary friction welding (RFW). EBSD analysis is used to certify the microstructure in different parts of the TAZ and to calculate the densities of the low- and high-angle boundaries. It is shown that complex processes of dynamic recrystallization combining several mechanisms develop in all these regions of the TAZ. Typical differences in the structures of the mobile (steel 40KhN) and immobile (steel 32G2) parts of the billets are described.

At the Navoi Mining and Metallurgical Combine, which uses a large number of machine parts for mining operations, the issue of optimizing the compositions of wear-resistant chromium cast irons while maintaining their operational characteristics has arisen. The paper presents the results of studying the phase composition of the cast alloy, as well as the effect of heat treatment of cast iron with a high chromium content on its structure and properties. As heat treatment operations, quenching in various modes and low tempering were used. The study made it possible to systematize the known literature data on the heat treatment parameters of a group of wear-resistant chromium cast irons, as well as to optimize their heat treatment modes for parts operating in mining and processing industry.

The present work was undertaken with the aim of studying the microstructural changes and intermetallic phases in Al-Si base 413.0 alloys as well as variations in tensile properties, including ultimate stress, yield strength and elongation at rupture, resulting from the addition of alloyed elements: strontium (Sr), magnesium (Mg), copper (Cu), silver (Ag), zinc (Zn) and nickel (Ni), to the base alloy 413.0, under different conditions of heat treatments, i.e., solutionizing and artificial aging (in the temperature range of 155 °C–240 °C). The results obtained in relation to microstructural observations and tensile tests reveal that the addition of alloying elements, in particular Mg, Cu, Ag, Ni, Zn and Sr, leads to an increase in the ultimate stress and yield strength values with a decrease in the strain levels of the base alloy 413.0, following hardening during artificial aging. Both Ag and Zn do not form specific phases during solidification at a slow rate of ~ 0.8 °C/s but only segregate to the α-aluminum cell boundaries. Addition of 0.73% Ag improves the values of yield strength at all aging temperatures. Also, it enhances the alloy resistance to softening during aging in the temperature range 200–240 °C. Similar behavior was exhibited by the addition of 2.5% Zn.

The microstructure, the phase composition, the microhardness and the wear resistance of hypoeutectic white cast irons with different contents of chromium are studied. It is shown that the wear resistance of the iron depends substantially on the type of the carbide phase and on the morphology of the ledeburitic eutectic, which is determined in its turn by the content of chromium.

The phase transformation behavior of lead and zinc in the high-lead slag reduction process was reported in this article. First, the occurrence state of lead and zinc in the slag and the phase transformation behavior of lead and zinc during reduction were investigated. Following, the thermodynamic modeling calculation for the reduction process was constructed and discussed. The results indicated that the zinc in the high-lead slag mainly existed in the form of zinc ferrite and silicate while the lead mainly existed in a silicate form. The XRD patterns of the reduced slag at different coal ratios demonstrated that the lead existing in the high-lead slag in a silicate form could be reduced into the metal phase while the zinc existing in the high-lead slag in the form of zinc ferrite (ZnFe2O4) could be converted into zinc silicate (Zn2SiO4), as the coal ratio increased. The thermodynamic modeling calculation results showed an agreement with the experiment analysis.

This paper discusses the effect of different combinations of preheating and post-heating on the corrosion and hydrogen embrittlement of Grade-91 steel weld joint in the as-welded condition. Though these welds are subjected to post-weld heat treatment (PWHT), there could be long delay in executing this, especially in the case of fabrication of large components, and during this delay, the welds in as-welded conditions are prone to environmental degradations like hydrogen embrittlement and different forms of corrosion. Though recommended minimum preheating and post-heating conditions are already known for welding of this class of steels, marginally increasing the temperature of preheating and post-heating or increasing the duration of post-heating can permit longer delay in the post-weld heat treatment (PWHT), without increasing the risk of environmental degradation. With this objective, a set of thirteen single-V multi-pass gas tungsten arc weld joints of Grade-91 steel fabricated with different preheating and post-heating combinations. Results indicated a significant reduction in residual tensile stresses in the weld metal and reversing into compressive stresses upon preheating and post-heating at 300 °C. Moreover, diffusible hydrogen content and corrosion rate decreased significantly with the preheating and post-heating. However, there are no significant variations in the microstructure, mechanical properties, and hydrogen embrittlement with preheating and post-heating. This study proved that the risk of embrittlement in Grade-91 steel welds due to an indefinite delay in PWHT could be minimized by combined preheating and post-heating.

The lightweight construction of steel structures is often limited by the mechanical properties of the weld metal. The strength values of modern base materials are not achieved in the weld metal. There is a considerable need to develop welding consumables that allow the processing of modern fine-grained structural steels without limiting their potential. The Physical Vapor Deposition (PVD) coating of welding wire electrodes can increase the strength of the weld metal of a Mn4Ni2CrMo welding wire electrode by up to 30%. By using different coating elements, the Hall–Petch relationship can be exploited and such an increase in strength can be achieved. Especially by applying titanium, vanadium, and yttrium coatings, the strength of the weld metal can be increased. Due to a multilayer structure of the coating, the weld metal and the process can be influenced independently of each other. The effects of mono-element coatings and multi-component coatings on the weld metal and the process are discussed. PVD coatings allow welding wire electrodes to be individually adapted to the requirements.

This article makes an attempt to investigate the outcome of activated flux and filler wire in addition to A-TIG welding and TIG welding of Inconel 625 respectively. Ni-Cr-Mo enriched filler namely ERNiCrMo-3 was used to join 6.5-mm-thick plates. Microstructure characterization, mechanical properties evaluation and secondary dendritic arm spacing measurements were carried out to find the cause of the perceived differences. Tensile test failures were observed at the weld zone in both welding processes. Charpy impact studies showed that weldment using A-TIG revealed a low toughness value compared to the TIG weldment. Root bend test showed no discontinuity in both fusion zones and hence, the weldment was produced without defect. The deleterious laves phase was reduced when activated flux and fillers were used. Corrosion performance was undertaken in a 3.5 wt% NaCl solution, to illustrate the outstanding corrosion resistance in Inconel 625’s fusion zone using A-TIG and TIG welding processes.