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The paper proposes a method for preparing composite powders of the Ti/TiB2 system, studies the properties of the obtained composite powders, and also shows a series of experiments on its microplasma spraying. The properties of the sprayed coatings were investigated. On its basis the optimal ratio of the matrix and reinforcing components was established in order to increase significantly the hardness of the sprayed coatings.

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.

A system was designed to detect possible violations of the operating rules of the enterprise without changing the behavior of the entire system as a whole, as well as to automatically start the assembly of the simulated behavior of a real application using unit and functional testing technologies. In the work, an analysis was made of the subject area of the work process of drivers, managers and operators. It was found that the time to find possible violations exceeds the permissible value. The audit department engaged in verification had problems with the quick unloading of potential violators. The department made unloading and manual search, which led to a longer identification of violations both from the side of drivers and managers. It is possible to solve this problem and increase the efficiency of the process by developing an automatic analysis system. An analysis of the management process was carried out. Based on the analysis, a model of system use cases was developed, from which user and functional requirements were defined and formed. A functional model of the system was introduced. The basic algorithms are described. Connections between system entities were revealed, analysis classes and detailed UML diagrams were compiled. Thus, when performing the work, all the features and nuances of the design of information systems were taken into account, then according to the presented models, you can develop an information system and implement it in various organizational structures.

The goal of the study is to consider the effect of explosion welding, heat treatment and cold straightening (gagging) in production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer on the evolution of residual internal stresses. The impact of technological operations on the change in the level of residual stresses in a bimetallic material with a welded butt joint in the cladding layer was carried out using a non-destructive method of the magnetic memory of metals (MMM). This method is based on the use of the intrinsic stray magnetic field formed in the zones of increased dislocation density. The results revealed the special features of the location of zones with maximum values of the stress field gradient (dH/dx) and their evolution upon production of 09G2S + 08Kh13 bimetal with a butt welded joint in the cladding layer. An increase in the level of residual stresses in the cladding layer occurs after manual electric arc welding of 2 parts of the cladding layer made of 08Kh13 steel. It is shown that after explosion welding the level of residual stresses change. The stress relaxation occurs in the zone of weld in the cladding layer. At the same time, an increase in the level of residual stresses is observed in the main and cladding layer of the bimetal. To reduce the high level of residual stresses, we used the subsequent heat treatment of the obtained bimetallic samples in two different modes. The optimal heat treatment mode (heating to 720 ± 20°C, holding for 2 h, cooling with a furnace) which excluded the crack formation in the cladding layer upon mechanical straightening of bimetal was specified for 09G2S + 08Kh13 bimetal sample with a butt welded joint in the cladding layer.

During contact flash welding of rails, the metal is heated and continuously cooled in the zone of thermal influence. Accelerated heating and subsequent intensive cooling, implemented by the pulsed flashing-off method, lead to the formation of quenching structures. Subsequently, during the operation of the rails welded joint, this leads to the formation of cracks and to brittle destruction. We have investigated the possibilities of using contact heating after welding to avoid the formation of quenching structures in the metal of the welded joint made of R350LHT rail steel. The thermal cycles during welding and subsequent contact heating were recorded. The regularity of formation of the weld metal structure was established including the zone of thermal influence during pulsed contact heating for R350LHT rail steel. It is shown that contact pulse heating slows down the welded joint cooling and prevents the formation of quenching structures. However, contact pulse heating when using suboptimal modes can also lead to the opposite effect. It is determined that with a significant investment of heat by contact heating, cooling rate of the metal exceeds the critical one, transformation process passes through a diffusion-free mechanism with the formation of martensite coarse-grained structure. The use of thermokinetic and isothermal diagrams of austenite decomposition at known thermal welding cycles allows us to significantly narrow the search limits for optimal modes of contact butt welding of railway rails and subsequent contact heating. The use of optimal contact heating modes makes it possible to obtain a minimum length of heat-affected zones with reduced hardness without the formation of quenching structures in the welded joint of railway rails.

A two-level control system for the temperature mode of smelting, out-of-furnace processing and preparation for casting of low-carbon steel G/ET is proposed in the conditions of BOF shop-2 of JSC “United West Siberian Metallurgical Combine”. Depending on the technological scheme, it is possible to design various control systems for the steelmaking complex with sequential, parallel and combined inclusion of individual operations and processes. The control system of a sequential group of objects is considered on the example of steel G/ET. The control system includes an external control loop that allows coordinated control of the shop departments by optimizing the mode of technological process conducting at the facility, taking into account the actual operation performed at the previous facility. The implemented nonparametric algorithm of dual control allows the decision-maker to perform joint operational adjustment of control actions for local control loops. The temperature mode of the melts of low-carbon steel G/ET is analyzed and it is revealed that the processing time of the steel ladle at each stage of the BOF – CCM technological route has a significant impact on the steel temperature mode. In accordance with this, the criteria for temperature control quality are formed. The results of computational experiment showed that the introduction of a control unit with a decision-maker contributes to the rational control of metal temperature mode in the BOF – CCM site, and as a result, obtaining a given chemical composition and temperature of steel within narrower limits. It allows one to eliminate deviations from the contact schedule of the main units, and to increase the number of melts in the series and the rate of continuous casting.

Tribotechnical tests and microstructural studies were carried out. Wear mechanism of nanostructured metalpolymer self-lubricating composite materials has been established. This mechanism involves in the formation of separating polymer layers on the friction surface, which reduces the coefficient of friction and running-in period of parts of friction units. Carbon nanoparticles move along the friction surface, hinder the development of seizure processes during the interaction of microroughnesses of the contacting surfaces of the material and the counterbody during the destruction of the separating polymer layers. It was found that the polymer filler is displaced from the friction zone, carbon nanoparticles are pressed into the open areas of the surface of the copper matrix of the composite when the pressure in the tribocontact is higher than 1.5 MPa. The temperature in the tribocontact increases, the polymer filler degrades, the carbon nanoparticles are removed from the friction zone, the strength properties of the composite decrease, the friction coefficient and the wear rate increase at a sliding speed above 1.5 m/s. The obtained research results can be used in mechanical engineering, transportation industry and power engineering.

Due to the complex composition and high proportion of alloys in traditional ultrahigh strength steel, the dilemma caused by ultrahigh strength and low toughness in casting and forging processes requiring subsequent heat treatment can be mitigated with an efficient and economical rolling process. In this work, the effect of deformation parameters on dynamic recrystallization (DRX) and dynamic recovery (DRV) is discussed through stress-strain analysis, the DRV mathematical model is obtained, and then the dynamic recrystallization activation energy, Zener–Hollomon equation, and hot working equation are obtained. The critical strain of DRX detected by the P-J method is ε c / ε p = 0.631 , which indicates that dynamic recrystallization of this novel steel is relatively easy to achieve by the rolling process. These models and conclusions have potential to be generalized for the formulation of process specification and process configuration without requiring extensive material testing.

Spent electroplating solutions contain small amounts of Pd(II). Cementation of Pd(II) with zinc metal powder is practiced to concentrate the Pd. Dissolution of the cemented Pd metal is necessary to recover pure Pd metal or compounds. In this work, the leaching behavior of Pd metal in inorganic acid solutions (hydrochloric and sulfuric acid) in the presence of an oxidizing agent such as H2O2, NaClO3, or NaClO was investigated. To determine the optimum conditions for Pd leaching, experiments were conducted by adjusting the concentration of the acids and oxidizing agents, reaction temperature and time, and pulp density. Complete leaching of Pd was possible using a hydrochloric acid solution with 3 kinds of oxidizing agents, whereas only NaClO was effective in the leaching with sulfuric acid solution. The chloride ions of HCl and NaClO3/NaClO play an important role in enhancing the leaching of Pd, due to the formation of Pd chlorocomplexes and by decreasing the reduction potential of Pd(II). Compared to H2O2, NaClO3 and NaClO showed some merits as oxidizing agents in terms of reaction time, temperature and low acid concentration. Based on the optimum leaching conditions of single Pd metal, the conditions for the complete leaching of Pd and Zn from the metallic mixtures were obtained.

Separation of ultrafine hematite from quartz and kaolinite gangue minerals using selective flocculation technique is markedly affected by the state of inter mineral interaction which is governed by type and content of polyvalent metal ions. Because of the presence of polyvalent metal ions hetracoagulation of gangue minerals is widely acknowledged, thus selective flocculation of ultrafine hematite from associated gangue minerals is challenging task when their concentration is above 10 ppm. This study has shown that state of strong interaction of gangue minerals with hematite due to presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions can be weakened by addition of optimal dose of Sodium Hexametaphosphate (SHMP) ligand. The optimization of ligand dose is achieved through analysis of Zeta Potential (ZP) as a function of slurry pH. It is noted that 50 ppm of SHMP is sufficient to restore the ZP of hematite, where selective dispersion of the slurry constituents are possible. Our results further showed that conventional strategy of obtaining minimum difference of ±30 mV in the ZP of hematite and gangue minerals quartz and kaolinite would not work especially in the presence of 15 ppm Ca2+, 3 ppm Mg2+ and 3 ppm Fe3+ ions. Attempts to achieve the minimum threshold difference in the ZP of the minerals will cause over dispersion.

Compound field–assisted laser cladding is an advanced laser processing technology. In this paper, the influence mechanism of single physical field parameters of electromagnetic-ultrasonic compound field–assisted laser cladding on the cladding layer as well as the parameter optimization of compound field–assisted laser cladding are investigated. The Box-Behnken design response surface methodology method is used for experimental design. Through the response surface modeling analysis, it is found that the ultrasonic power has the greatest influence on the microhardness of the cladding layer. For the wear volume of the cladding layer, as the ultrasonic power increases, the wear volume increases and the wear resistance of the cladding layer decreases. Besides, a smaller ultrasonic power and a larger DC current value can obtain a cladding layer with a smaller wear volume. The optimal combination of physical field parameters was obtained through response surface methodology parameter analysis and experimental verification.

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.

The hot cracking susceptibility in the Trans-Varestraint test was evaluated using the nominal strain calculated using the curvature radius of a bending block and the thickness of a specimen based on the theory of material mechanics. The nominal strain was calculated using the material properties at room temperature. Thus, in the Trans-Varestraint test, the non-uniformity of the strain around the weld part due to the temperature distribution is not considered. Therefore, the strain in the Trans-Varestraint test cannot be evaluated correctly. The aim of this study is to reveal the loaded strain at the weld metal to understand the evaluation of hot cracking susceptibility in the Trans-Varestraint test. The loaded strain around the trailing edge of the weld pool of pure iron was measured in-situ using a high-speed camera and high-resolution optical lens. The results of strains measured using image analysis and the finite-element method at the center of the weld bead were compared. Accordingly, it was clarified that the strain was concentrated on the weld part owing to the bending occurring along the weld line, and the strain exceeding the nominal strain was loaded to the trailing edge of the weld pool.

Alloy 825 is a nickel-based alloy that is commonly used in applications where both high strength and corrosion resistance are required, such as tanks in the chemical, food and petrochemical industries and oil and gas pipelines. Components made from Alloy 825 are often manufactured using hot deformation. However, there is no systematic study to optimise the processing conditions reported in literature. In this study, a processing map for as-cast Alloy 825 is established to maximise the power dissipation efficiency of hot deformation in the temperature range of 950 to 1250 °C at an interval of 50 °C and strain rate range of $$0.01\, {\text{s}}^{ - 1}$$ 0.01 s - 1 to $$10.0\, {\text{s}}^{ - 1}$$ 10.0 s - 1 to a true strain of $$0.7$$ 0.7 using a Gleeble-3500 thermomechanical simulator. The processing conditions are also correlated to the Vickers hardness of the final material, which is also characterised using optical microscopy and scanning electron microscopy, including electron backscattered diffraction. The true stress-true strain curves exhibit peak stresses followed by softening due to occurrence of dynamic recrystallization. The activation energy for plastic flow in the temperature range tested is approximately $$450\,{\text{ kJ mol}}^{ - 1}$$ 450 kJ mol - 1 , and the value of the stress exponent in the (hyperbolic sine-based) constitutive equation, $$n = 5.0$$ n = 5.0 , suggests that the rate-limiting mechanism of deformation is dislocation climb. Increasing deformation temperature led to a lower Vickers hardness in the deformed material, due to increased dynamic recrystallization. Raising the strain rate led to an increase in Vickers hardness in the deformed material due to increased work hardening. The maximum power dissipation efficiency is over $$35\%$$ 35 % , obtained for deformation in the temperature range 1100-1250 °C and a strain rate of $$0.01\, {\text{s}}^{ - 1}$$ 0.01 s - 1 -$$0.1\, {\text{s}}^{ - 1}$$ 0.1 s - 1 . These are the optimum conditions for hot working.

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.

The laser-MAG hybrid welding in horizontal-vertical (PC) position was used to study the effect of different groove types on the quality of a root weld. Six combinations of bevel angles (50° + 0° (represents the groove angle of upper plate and lower plate respectively), 45° + 5°, 40° + 10°, 35° + 15°, 30° + 20°, and 25° + 25°) and root face sizes of 2 to 4 mm were designed. Hannover analyzer was used to collect electrical signals to analyze the stability of the horizontal-vertical position welding process. The results show that different combinations of groove angle have achieved one-sided welding with root formation. The groove angle has an obvious effect on the weld inclination and molten weld metal flowing down. The combination of bevel angles in which that of the lower plate is smaller than that of the upper plate was more conducive to avoid welding defects such as weld inclination and molten weld metal flowing down. The best groove angle combination was 30° + 20°, which allowed one-sided welding with root formation using a 4-mm root face.

In this paper, dissimilar joining of NbSS/Nb5Si3 composites to GH5188 Co-based superalloy was performed by using two commercial Ni-based brazing filler alloys, BNi-2 and BNi-5 fillers. The interfacial microstructures of the brazed joints were investigated by scanning electron microscope equipped with an X-ray energy dispersive spectrometer. Three-point bending test was also conducted. When brazed with BNi-2 filler alloy at 1020°C for 15 min, typical reaction products across the brazing seam could be identified as NiSS, borides, Ni3Si+Nb3Si, and (Nb,Ti)2Ni phase. Due to the physical and chemical mismatch between the dissimilar base materials, some cracks were observable at the NbSS/Nb5Si3 composites side. The joint strength was only 60 MPa. While brazed with BNi-5 filler alloy at 1160°C for 15 min, the interfacial reaction became more sufficient, and the joints exhibited an average bending strength of 272 MPa.

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 present study is aimed to investigate the effects of zinc electroplated coating and hot dipping at 480 °C on the microstructure and mechanical properties of pure aluminum/40NiCrMo2-2 steel bimetal interface produced by compound casting at 780 °C. Accordingly, microstructural studies and interface shear strength were determined using optical microscope, scanning electron microscope, and push-out test. Results showed that the interface layer in all the samples, independent from the coating type, is composed of two sub-layers of Fe2Al5 and FeAl3. Furthermore, the linear analysis results and elemental distribution map of the interface indicated that no considerable amount of zinc was present in the interface of the samples. Based on the results, the maximum strength was related to the electroplated sample with the value of 45.1 MPa, while the hot-dipped sample had the strength of 37.5 MPa, which was attributed to the formation of interface layer with less defects in the electroplated sample.

An isothermal diagram of decomposition of supercooled austenite of R350LHT steel was constructed based on the results of dilatometric, metallographic and hardness analysis of this decomposition during continuous cooling and under isothermal conditions. When comparing the thermokinetic and isothermal diagrams, it was found that the thermokinetic diagram plotted during continuous cooling shifts downward and to the right in comparison with the isothermal diagram. This result is fully consistent with the known regularities. During the research, the critical points of R350LHT steel were determined: Ас1 = 711 °С; Мn = 196 °С. This isothermal diagram was used to determine the temperature of the minimum stability of overcooled austenite, which was 500 °C. Under isothermal conditions, pearlite-type structures appear in the temperature range from 700 to 600 °C. At 550 °C, a mixture of pearlitic and bainitic structures is formed. In the temperature range from 500 to 250 °C, bainitic structures are formed: at 500 – 400 °C – upper bainite; at 350 ° C – a mixture of upper and lower bainite; at 300 – 250 °С – lower bainite. Almost in the entire studied temperature range of overcooled austenite isothermal decomposition, an increase in the hardness of the transformation products is observed with a decrease in the holding temperature from 246 HV (at 700 °C) to 689 HV (at 250 °C). However, at a temperature of 500 °C, a slight drop in hardness occurs, which is apparently caused by the appearance of retained austenite during the development of bainitic transformation.

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.

Semisolid 357 Al alloy slurry was prepared in the presence and absence of electromagnetic stirring (EMS) and rheo-diecast with various injection velocities, the microstructure, porosity and mechanical properties of the 357 rheo-diecast (RDC) samples were quantitatively analysed as well as their relationships were explored. The results show that injection velocity had greater influence than EMS on the rheo-diecasting process. Injection velocity and EMS had minor influences on the secondary particles but marked influences on the primary particles. For primary particles, increasing injection velocity led to a decrease in particle diameter and an increase in shape factor. EMS can reduce the size and improve the shape factor of primary particles and large pores. The injection velocity was 0.53 m·s−1 at which the optimal values of the porosity and the shape-diameter ratio of the maximum pore for 357 RDC samples, i.e. 0.37% and 1.43 μm−1, can be obtained in the presence of EMS, corresponding to the highest tensile strength and elongation of 274 MPa and 4.85%. The tensile properties were correlated linearly with shape-diameter ratio. It was also suggested that the mechanical properties were enhanced by EMS on account of the reduction of porosity and increase in shape-diameter ratio.

In the present work, the microstructure and mechanical properties of microwave welded Al6061-6%Graphite-SiC hybrid metal matrix composites (MMC) were investigated. The microwave welding was carried out using the principle of microwave hybrid heating and Al6061 powder as an interfacial material. The domestic microwave oven having the frequency of 2.45 GHz and 900 W power was used for the experiments. The charcoal powder as a susceptor was used during the welding process. The hybrid MMCs Al6061-6%Gr-SiC were developed through stir casting process with different weight percentage of SiC keeping graphite constant. The joints were characterized using x-ray diffraction, scanning electron microscope (SEM) equipped with energy-dispersive spectrum (EDS), Rockwell hardness tester and universal testing machine. The x-ray diffraction analysis showed the presence of harder aluminum carbide and aluminum oxide phases. The microstructural study revealed the good metallurgical bonding between the interfacial composites with absence of cracks. The elemental analysis of joint revealed the presence of aluminum, carbon and oxygen with other elements. The average ultimate tensile strength of the microwave joints was recorded as 135 MPa with 4.3% elongation. The average Rockwell hardness at the weld joint observed was 61.5 ± 5 HRB. The evaluation of mechanical properties of microwave welded composites indicated the increase in the tensile strength and hardness as the content of SiC reinforcement increased. The joint strength found to be 65.15% of parent composite, which is similar to the joint strength of welded aluminum-based composites by various techniques such as friction stir welding, laser beam welding, electron beam welding, etc. The present investigation has showed that the microwave energy can be used successfully, as an alternative method to weld the composites.

In this research, the effect of annealing heat treatment on microstructure, mechanical properties and wear behavior of an Al–Zn–Mg/3 wt.% Al2O3 composite that was previously thermomechanically processed (TMPed) in its semisolid temperature range was investigated. The annealing treatment was conducted at 400 ˚C for 15, 30, 45 and 60 min, respectively. The results revealed that this treatment led to the better distribution of alumina reinforcement particles. Also, it was proved that no substantial grain growth occurred which shows the grain size stability of the TMPed composite. In addition, owing to the better distribution of reinforcements, the microhardness values of the composites improved while the compressive strength did not increase noticeably. The wear test results revealed that the wear mode in the non-annealed sample was adhesive whereas in the annealed sample, the abrasive wear was dominant.

In this paper, the lamellar orientation control and mechanical properties of directionally solidified (DS) Ti-49Al (at%) alloy in oxide ceramic crucible were investigated. Based on the nucleation undercooling theory, the feasible solidification parameters for the lamellar orientation control of Ti-49Al (at%) alloy by the seeding technology were selected. The optimal solidification parameters were as follows: the growth rate (V) ranged from 10 to 25 μm/s, and temperature gradient (G) ranged from 10 to 20 K/mm. DS Ti-49Al (at%) alloy with paralleled lamellar orientation was successfully prepared according to the predication solidification parameters. The mechanical properties of DS Ti-49Al (at%) varied with the orientation of the lamellar structures. The specimen with paralleled lamellar orientation showed relatively higher tensile strength (450 MPa) and elongation (0.60%). The mechanical properties of specimens with paralleled lamellar orientation were greater than the specimens with equiaxed grain structures even though the specimens contaminated slightly by the interfacial reaction between the TiAl melt and the oxide ceramics crucible. Meanwhile, the fracture modes of DS Ti-49Al (at%) alloy were interlamellar mode, translamellar mode, or combined with the two modes, which also depended on the lamellar orientations.

Change is constant, as nothing stays the same. Consider the words of the Chinese philosopher Lao Tzu, “Life is a series of natural and spontaneous changes. Don't resist them—that only creates sorrow. Let reality be reality. Let things flow naturally forward in whatever way they like.” Some changes are the result of biology and the passage of time, within the natural cycle or order of things. Others are self-generated, under our own control and resulting from willful efforts, or dependent upon encounters with significant others—family, friends, colleagues, and others close to us. Still, other changes occur because of circumstance or fate, a proverbial "date with destiny" and often beyond what we feel is our control. Whether it is our personal life or occupational, like metalcasting, this change can facilitate transition and transformation. I have coined the term metalmorphasis and this lecture as reflection of how to embrace change, recognize the opportunities presented and utilize it as a vehicle for new beginnings. This is not just philosophical but also a look how we as metallurgist and metalcasters apply and control input variables (time, temperature, pressure, chemical reactions, etc.) to transform metals and create metalmorphasis.

The effect of Eu (Europium) element on eutectic Si in Al–7Si alloys was studied by scanning electron microscopy (SEM), thermal analysis, electron backscattering diffraction (EBSD), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to elucidate modification mechanism of Eu on eutectic Si. The results indicate that the addition of Eu changes the morphology of eutectic Si from coarse plate-like to fine fibrous. With the increase in Eu content, the number of eutectic cells gradually decreased and the size of eutectic cells increased. Meanwhile, the eutectic nucleation temperature (TN) and the minimum temperature (TMin) decreased, which is caused by the poisoning of AlP particles by Eu. The segregation of phosphorus was found at the center of coarse Al2Si2Eu particle, and the "phosphorus layer" was found at the boundary between the Al2Si2Eu particle and matrix. The length direction of plate-like eutectic Si was , and its outer surface was {111} plane. Few parallel twins were observed in unmodified plate-like eutectic Si. However, the growth of Eu-modified fibrous eutectic Si was isotropous. Multiply twins were often observed in fibrous eutectic Si after modification. The adsorption of Eu was observed along the Si growth direction of eutectic Si and at the intersection of two {111}Si twins, verifying the existence of the poisoning of the TPRE mechanism and IIT mechanism.

This study experimentally investigates the influence of adding SiC on microstructure and mechanical properties of the aluminium alloys welded joints. The SiC particles have been directly added into a zone of friction stir welding (FSW) to make (AA6061–AA2024) SiC composites material. Results show that the effect of adding SiC particles on microstructure refines the grain size in the stir zone by preventing its growth during FSW process. The adding of SiC particles has a significant effect on the thermomechanical zone resulting from restricting the growth of grains. Results indicated that the microhardness of FSW joints is increased from 44 to 86 HV by adding 9.2% SiC particles as compared to that obtained without including SiC under the same welding conditions. It has been observed that the tensile strength is enhanced when the amount of SiC particles are increased by up to 6.9%.

Decrease of energy intensity of products is an actual task for all the industries, including steel industry. One of the best solutions to increase energy efficiency of heating facilities is application of recuperative and regenerative burners, which ensure high temperature of air heating. Such high temperatures cannot be achieved at application of heating systems based on central recuperator. It was shown that many countries accomplish studies to perfect recuperative burners and simulation of their thermal operation. However at present there are no universally recognized methodologies of calculation and designing of such equipment. Results of studies presented, which were implemented in three methodologies intended for heat calculation and selection of rational parameters of regenerative burners operation. The methodologies enable also to determine a fuel utilization coefficient for a furnace system based on regenerative burners, to estimate competitiveness of solutions at creation new and modernization existing furnaces comparing with utilization of modern central recuperators. Comparative simplicity of the mathematical apparatus used in the methodologies highlighted, as well as correspondence of the used calculated expressions to the physical nature of the processes taking place. Besides, the methodologies enable during calculation to set the values of important characteristics, which can be reached based on determination of values of basic structure parameters of lining. A scheme of joint application of the elaborated methodologies proposed.

A novel alternating-frequency ultrasonic melt treatment (AUMT) technology is used to refine the grain and improve the strength of AS41 magnesium alloy. The AUMT exhibits better grain refinement efficiency than the traditional 20 kHz single-frequency ultrasonic melt treatment method, showing the grain refinement efficiency up to 82.7%. The improvement of cavitation is suspected to be the reason for better grain refinement. The faster alternating time is beneficial to improve grain refinement efficiency. The AUMT also refines the Mg17Al12 and eliminates the agglomeration of Mg2Si. Such microstructure evolution helps improve the tensile strength and elongation of AS41.

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”.

Modern products and structures require efficient material joining processes for their construction, able to combine similar or dissimilar materials, which almost always includes high-performance polymers. To design such joints, it is necessary to first understand the techniques currently used in this technological field and how they can be improved using advanced technological joining processes. In this manuscript, a review of several polymer-joining techniques is made, highlighting the recent technological advances in this field. The search for improved mechanical performance and lower costs has led to the development of new, high-performance engineering polymers, which require highly specific joining processes. These can include adhesive bonding, mechanical joining, welding or a combination of different processes, a technique known as hybrid joining. Several experimental works available in the literature have proven the validity of these techniques, although optimization processes are necessary to attain maximum performance. Additionally, extensive numerical with different methods and models has been carried out to better understand the processes and support parametric analysis. The intent of this work is to review studies on the most important polymer bonding techniques, the numerical models applied to simulate these techniques, the use of hybrid joints and describe promising techniques that are being developed and proposed for future use.

The article deals with the problems arising during the mechanical and thermal treatment of the TMZ-450D diesel engine cylinder, which is the base part of the engines of small-sized generators and compressors, which are widely used for mobile units in the oil and gas and mining industries. It was found that the metal in the casting has a non-uniform structure, the density of which ranges from 6.75 to 7.25 g/cm3. Redistribution of dislocations and residual stresses in the casting leads to significant changes in the size and shape of the main bore. In addition to the successive changes in size specified by the technology due to the removal of the designated allowance, the dimensions and shape change arbitrarily, uncontrollably in the course of the technological process. It is shown that artificial aging by a thermal method does not provide the desired dimensional stability; therefore, it is proposed to supplement it with natural aging after rough boring for six months. It was revealed that the use of morally and physically outdated equipment makes it necessary to increase the number of finishing operations of honing and, accordingly, to increase the labor intensity of cylinder manufacturing. The use of a two-position boring machine is substantiated, on which the transitions of semi-finishing and fine boring are combined. This completely eliminates the copying of errors that arose when changing the base on previous operations. The use of a two-position modular boring machine ARS-4/Ts of increased accuracy and rigidity significantly increases the accuracy of the bore hole, which makes it possible to reduce the number of honing operations. A variant of the technological process of mechanical and heat treatment is proposed, including natural aging, the use of double boring on a modular boring machine, which will reduce the number of honing operations to one, including rough and finish transitions.

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.

Active vision sensing is widely used in intelligent robotic welding for bead detection and tracking. Disturbed by welding noise such as arc light and spatter, it is a hard work to extract the laser stripe and feature values. This paper presents a method for denoising and feature extraction of weld seam profiles with strong welding noise in gas metal arc welding (GMAW) process by using stacked denoising autoencoder (SDAE). This algorithm encodes the images of various butt joints with strong welding noise to several useful intermediate representations, which can be decoded to the image of pure laser stripe in 1-pixel width. The results show little deviations when there are large spatters across the laser stripe. A back propagation neural network (BPNN) is developed to verify the reliability of the intermediate representations gotten from the encoder, in which the intermediate representations are input neurons and the weld seam width is output neuron. The average width error in training dataset and testing dataset is 0.042 mm and 0.061 mm. The results show that this algorithm can extract the weld seam profiles with strong welding noise and extract feature values accurately.

High-energy density beam processes for welding, including laser beam welding and electron beam welding, are essential processes in many industries and provide unique characteristics that are not available with other processes used for welding. More recently, these high-energy density beams have been used to great advantage for additive manufacturing. This review of the literature serves to provide an overview of the evolution of the laser and electron beam processes including the fundamental nature of the beam itself and how such a high-energy density beam has been applied for welding. The unique nature of each process regarding weld bead formation and penetration, and metallurgical considerations are covered in detail. In addition, the evolution of monitoring systems for both characterization and control of these beam processes is reviewed. Over 500 references have been cited in this comprehensive review that will allow the reader to both understand the current state-of-the-art and explore in more detail the fundamental concepts and practical applications of these processes.

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.

The joining of the SiCf/SiBCN composite was difficult due to the undue reactions between the SiCf/SiBCN composite and the common Ni- or Co-based filler alloy. In this paper, a new filler alloy with the nominal composition of Co-20Ni-12Pd-18Nb-15Cr (wt.%) was newly designed to join the SiCf/SiBCN composite. Compared with the BNi-5 filler alloy, the periodic banded structure in the reaction layer was eliminated. During the brazing process, the element Cr played an active role in the interfacial reactions and formed Cr23C6 layer at the surface of the SiCf/SiBCN composite. The interfacial reaction layer could inhabit the diffusion of the elements Co and Ni to the SiCf/SiBCN substrate. And then the interfacial reactions were controlled well. Under the brazing condition of 1200 °C/10 min, the average joint strength was increased from 18.2 to 54.9 MPa.

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 grain growth mode of titanium alloys remains controversial. In this study, ANSYS and cellular automaton-finite difference code μMatIC were coupled to simulate the multi-scale solidification process of commercial purity titanium and two types of titanium alloys with different solute concentrations. Investment casting of Ti–6Al–4V was carried out in counter-gravity casting method in vacuum environment. Results showed that the grain growth mode of titanium alloys depended on the solute compositions. Grain growth mode of titanium alloys transfers from planar to dendritic with the increased solute. The grain growth morphology of Ti–6Al–4V alloy presents cellular dendritic due to slight solute segregation in the solidification. The predicted grain structure was validated by comparison with the microstructural observation results. Both the prediction and experimental results revealed that equiaxed grains were obtained in investment casting of Ti–6Al–4V regardless of the thickness. The grain size increased with the wall thickness of the cast part.

The influence of Si additions (0.1, 0.3, 0.6, 1 wt%) on microstructure, hardness and elevated-temperature sliding wear behavior of AX53 magnesium alloy (Mg—5 wt% Al—3wt% Ca) has been investigated by performing a ball-on-disk high-temperature wear test at different temperatures (RT, 100, 150, 200 °C). The results clearly show that without Si addition, the microstructure of the as-cast AX53 alloy consists of dendritic primary α-Mg phase and lamellar eutectic structure consists of layers of α-Mg and (Mg, Al)2Ca lamellar intermetallic compounds that alternate together. With Si additions, a new intermetallic compound rich in Si can be defined as MgCaSi of a granular, needle and bulky morphologies with different sizes forms within the inter-dendritic regions of α-Mg. Formation of fine granular MgCaSi intermetallic compounds as well-distributed particles is associated with the addition of 0.6 wt% Si. The alloy containing 0.6 wt% Si shows the highest hardness value and the best wear resistance at all temperatures of the wear test. In the Si-containing alloys, weight loss increases with increasing the temperature of wear test compared to the RT wear test regardless of the Si content. However, the Si-containing alloys have lower weight loss than the investigated alloy without Si addition. The wear mechanisms have been also discussed.