Progress in Materials Science and Engineering

Based on the analysis of the experimental C-shaped TTT diagrams of undercooled austenite, the study proposes a method for calculating the kinetic parameters of the Avrami equation and for determining the activation energy for pearlitic and bainitic transformations. To this effect, upon the TTT curve digitization, the kinetic curves were plotted for the volume fraction of undercooled austenite at different transformation temperatures. Case-specific n and A parameters were calculated for the Avrami equation. Temperature dependence of the A parameter makes it possible to determine the activation energy for pearlitic and bainitic transformations. The temperature dependence of activation energy is shown to be fitted with a hyperbolic curve. An equation is suggested to describe the activation energy as a function of austenite supercooling. The parameters thus obtained make it possible to describe the temperature time kinetics of the pearlitic and bainitic transformations.

The paper is devoted to the structure and behavior of Cu-Ni-Zn system cast bar under the lost-wax method. A method of estimating casting mold fillability has been proposed. The method involves determining perforated plate-filled cell fraction. The effect of casting temperature on casting mold fillability and casting bar structure has been studied. The casting temperature of Cu-15Ni-20Zn alloy is determined as 1190 °C; it ensures the best casting mold fillability. Moreover, the influence of an alloying addition such as Sn and Al on casting mold fillability and the behavior of Cu-Ni-Zn alloy under mechanical testing have been studied. The addition of 4.0 mass % Sn and 0.4 mass % Al enables increasing casting mold fillability by 5% and reducing casting temperature to 1170 °C. It has been established that the alloying addition of elements such as Sn and Al makes a more compact and close-grained microstructure, increases the mechanical properties of Cu-Ni-Zn alloy by 10–12% and improves the cast bar surface considerably. In all cases melting and casting were performed by an INDUTHERM-MUVV700 machine. Casting investment mold annealing was carried out in the same step-by-step conditions. The temperature of all molds before casting was set at 560 °C.

As the title implies, the paper describes structural changes in a new practically carbon-free, aluminium-containing Fe-Cr-Ni-based steel. This steel has been developed for the debugging of industrial austenitic-ferritic steels (σ-phase and 475-temperature brittleness). Abnormally high microhardness of δ-ferrite, approximately equal amounts of austenite and δ-ferrite of the austenite-ferrite structure and the typical needle Widmanstatten structure of reversed austenite have been shown by magnetometric, dilatometric and microstructural studies. Recommendations are given for hot plastic deformation rates of the investigated steel. In conclusion, one can say that the steel 03Kh14N10K5M2Yu2T overcomes the drawbacks inherent to industrial duplex steels and the embrittle σ-phase is not precipitated in the steel structure in the temperature range of 1200–900 °C. The aim of this study is to investigate the solidification of δ-ferrite, an austenite-ferrite structure of the steel in the quenched state from 1000 °C, and the microhardness of δ-ferrite and reversed austenite in the austenitic-ferritic structure.

The correlation of instrumented Charpy data analysis with fracture mechanisms in API 5L grade X80 pipeline steels has been investigated. Optical fracture analysis has shown solely the occurrence of ductile zones on a fracture surface: shear zone L _C, “lamellar” zone L _B with separations, and shear lips λ. New parameters of smoothed instrumented impact load vs. displacement curves are suggested for the characterization of impact properties. Co-analysis of the instrumented impact test curves and fracture surface zones allows evaluating crack resistance in addition to standard required characteristics (Charpy toughness, transition temperature, impact yield strength, etc.).

Damping is an important property of porous materials that defines its application for vibroinsulation. Damping of cast-replicated aluminum alloy AlSi7 (porosity 52–54%) has been investigated. In order to produce the specimen, the technique of vacuum impregnation of a leachable porous loose bed was applied. Damping was measured as the logarithmic decrement of free bending beam vibrations. Damping versus maximum strain amplitude of porous bending beams for various pore sizes has been obtained. As compared to the metal foams of higher porosity (85%), there is no considerable influence of pore size on the damping of replicated aluminum foam of small pore size (<1.6 mm). On the contrary, the damping behavior of replicated aluminum foam with coarse porous structure was like that of a metal foam.

This paper is devoted to the investigation of fine dust hydrometallurgical treatment by a new reagent – oxyethylidenediphosphonic acid, commonly known as OEDP. Dust leaching tests were made following an experimental design plan. Varied experimental parameters included liquid-to-solid ratio (X₁) from 3 to 7 and process temperature (X₂) from 25 °C to 80 °C. Extraction of lead (main component), zinc, copper, and iron has been monitored during the tests. Response surfaces for leaching optimization were designed using STATISTICA 7.0 software. These planes describe temperature and liquid-to-solid ratio dependences of lead, zinc, copper, and iron extraction in media. Optimal parameters were specified for alkaline leaching of lead and zinc from fine dust of copper smelting plants. These parameters are initial concentration of OEDP 1.5 mol/l, pH 11–12, l:s = 5:1, and temperature 30–50 °C. At these conditions, the extraction was Pb 96–98%, Zn 15–20%, Fe 1–3%, and Cu 0.05–0.1%.

Lead, zinc, and arsenic circulate in the intermediate products of metallurgy enterprises because of the bad quality of the concentrates used and the inclusion of secondary raw materials into the process. These intermediate products are mainly represented by dusts. Recycling of these dusts in smelting aggregates leads to the contamination of blister copper with arsenic and lead. This chapter presents some results of oxidizing sulfuric acid pressure leaching and leaching with copper sulfate solution of mattes obtained from the joint reduction smelting of these dusts. The option of cake treatment after pressure leaching with a copper sulfate solution is shown here. The oxidizing sulfuric acid pressure leaching is carried out in the temperature range of 140–180 °С, acidity range of 10–80 g/dm³, and pressure of 0.4 MPa that allow one to extract 94.2% of copper into the solution. Iron, arsenic, and lead remain in the cake after leaching even after the repeated leaching. This fact makes it difficult to process the cake at the lead enterprises by a conventional technology. The pressure leaching with a copper sulfate solution of mattes is proposed as an alternative to the oxidizing sulfuric acid pressure leaching. This leaching allows one to extract up to 93% of arsenic, zinc, and iron into the solution in the temperature range of 140–180 °С. The cake after pressure leaching with copper sulfate solution may be subjected to the oxidizing sulfuric acid pressure leaching to obtain a lead cake which may be used at lead plants. There is a scheme of processing of mattes including the pressure leaching with a copper sulfate solution as one of the basic operations followed by the oxidizing sulfuric acid pressure leaching.

Top submerged lance (TSL) furnaces are still new to Russian metallurgy. The first metallurgical plant to use such furnace was “Karabashmed” at Karabash. It uses a single TSL-type furnace as their main smelting unit since 2007. Two more plants – Mednogorskiy Mednoserniy Combinat (at Mednogorsk) and Svyatogor (at Krasnouralsk) – are planning to switch from reverberatory furnace (Svyatogor) and shaft furnace (Mernogorsk) to TSL furnaces too in the near future.

Due to this trend, understanding of TSL furnace operation is becoming vital for scientific groups working with the mentioned plants, and, therefore, we started our investigation with the properties of this process to find possible fields for improvement and optimization.

A cold model of TSL furnace was built using Plexiglas and plastic tubes in a scale of 1:12 to real furnace. It features several lance options, including single, two-tube, three-tube, and different swirl solutions. Blowing was performed using a 300 l/min compressor; video was captured using two 100 fps cams. The liquids used were water and different oils.

A series of experiments was conducted using this model to obtain data for future CFD modeling of the process. Parameters varied during experiments including lance height, lance size, swirl form, and amount of air blown.

We measured pressure at the lance tip, torch size, calculated Reynolds criteria and torch penetration depth.

Nowadays, great attention is being paid to the recycling of copper-containing materials. Especially for the secondary copper-containing material treatment, rotary bevel drum-type furnaces are used. Such furnaces are mainly represented by the Kaldo furnace and the tilting rotating oxy-fuel (TROF) converter. In Russia, a number of such units are in use. The main advantage of these furnaces is a strap slag processing facility. Such slag is formed because of the high zinc and tin content in the feedstock. The ability of slag mixing allows one to obtain waste slag with a low copper content.

Due to the application of the unsubmerged blowing and a rotating smelting chamber, a material flow trajectory is difficult to be predicted. For a better understanding of the TROF converter operation and for finding possible ways for hydrodynamic improvement, cold simulation has been carried out.

The TROF converter cold model was constructed of plexiglas at a scale of 1:10 to a real furnace and equipped with a steel lance. The model may simulate furnace rotation, and the angles of furnace drum and lance may be set independently. During the experiments, the following parameters were varied: the angle of the model body, lance angle and position, volume of liquid in the model, and airflow rate. For simulation, water and different oils were used; blowing was performed by compressed air. To record the results, two 100 fps cams were used.

The obtained results permitted us to calculate the energy balance. The relationship between an airflow penetration depth and airflow rate was determined. In addition, a number of dead zones were detected in the furnace molten bath. By means of video recording, a torch size and a volume of displaced liquid were determined.

Thermodynamic features studies of the polymetallic sulfide raw material nitric acid leaching were carried out. Elemental and phase composition of the raw material under investigation was studied with X-ray diffraction and electron microscopy methods. Calculations of the Gibbs energy change for the likely reactions of sulfide minerals with nitric acid were performed. The most favorable conditions for the leaching process were identified with a Pourbaix diagram. The results showed that for maximum transfer of the metal sulfides into sulfate form, the necessary initial oxidation potential is E >0.9 V wherein copper and zinc go into solution completely. The interaction of the metal sulfides with nitric acid leads to its degradation and the formation of nitrous gases. The resulting nitrogen oxides are oxidized to higher oxides in the absorption column to form a mixture of nitric and nitrous acids. The resulting mixture was used in the next leaching stages.

Surfactant application in hydrometallurgical technologies intensifies leaching and electrolysis processes. Lignosulfonates proved their effectiveness in oxidative pressure leaching of zinc sulfide concentrates. Lignosulfonates act as dispersing agents, removing impactful molten sulfur layer from the mineral surface during leaching. However, lignosulfonate application has negative influence on further processes of purification from Cl, Fe, Cu, Ni, and Co. This phenomenon might be related to incorrect reagent dosage. In this paper, the adsorption mechanism was investigated by two different lignosulfonates on surfaces of natural sphalerite and zinc concentrate. Characteristics of adsorption change versus sulfuric acid concentration variation and adsorption isotherm were acquired. It is shown that lignosulfonate adsorption depends significantly on lignosulfonate composition, lignosulfonate and sulfuric acid concentration, and adsorbent nature.

The paper presents an analysis of the current state of mineral processing of copper, copper-zinc, zinc-lead and copper-lead-zinc-pyrite ores. The most significant problem for selective flotation is posed by the domination of iron sulphides over non-ferrous metal sulphides in various ores. In many types of ore, pyrite content reaches 90%; in some ores, pyrrhotite content prevails over pyrite by twofold and comprises 50–60%. The content of copper fluctuates over a wide range from 0.7% to 3% with zinc content ranging from 0.7% to 3.5% or more. The bulk of copper in ores is represented by chalcopyrite. In some sulphide ores, the content of secondary copper sulphides is increased by 30%, whereas the content of tennantite and tetrahedrite reaches 25% of the total copper mass. Using the aeration and weak sulphhydryl collectors’ relative of pyrite, pyrrhotite and inactive sphalerite such as the M-TF in combination with butyl xanthate improves the selectivity of flotation. The technology for complex ore processing was developed to produce rich flotation concentrates and poor polymineral products for hydrometallurgy. The correlation between the basic properties of minerals and the technological schemes, regimes and processing indicators of non-ferrous metals has been identified.

The influence of a waterproofing penetrative capillary mixture on the composition and structure of cement stone was considered. It was shown that the change in the cement stone structure under the influence of a waterproofing permeable capillary mixture is accounted for by the interaction in general of the СO₃ ²⁻ and HCO₃ ⁻ and HCOOal by t²⁺ and SO₄ ²⁻ SOtHCOOal for the cement hydration products, that is, hydroaluminate of calcium and portlandite, to form the corresponding AFt and AFm phases as well as calcite. Calcium hydrosilicate needles play the most important role in the formation of the waterproof cement stone structure.

The paper is devoted to the processes of the hardening of composite cements modified with a polymer addition. Fly ash, limestone meal and marble powder have been used as mineral additions to Portland cement to obtain composite cements. Binary systems (“cement-mineral addition”, “cement-organic modifier”) and complex binding systems have been studied. The properties of composite cements have been investigated by means of a triangular surface design. Experimental results on the strength of composite cements are presented.

A new method of producing unburnt ash gravel of high strength has been developed. The gravel consists of fly ash obtained from the heat power industry, Portland cement screening from rock crushing and accelerator of hardening. The method involves proportioning and mixing the components, moistening the mixture, forming the granules of the required coarseness of grading, heating and moistening the grains and fractioning. As far as the strength of the gravel is concerned, it stems from two factors: the acceleration of clinker mineral hydration under the influence of Na₂SO₄ and the packing of the fly ash cement stone structure. As hornblendite is a chemically inert material, it is used as a filler agent. The unburnt ash gravel has the following properties: density 900 kg/m³; compressing strength 7.5 MPa; frost resistance, F50 and water absorption 10%. It is recommended to use the unburnt ash gravel developed as coarse aggregate to lighten the construction concretes. In fact, practical implementation of the method in question enables a 5–10% reduction in construction costs.

The paper is devoted to a complex study of the processes involved in the distribution of glass batch components during their preparation and mixing. The distribution of various particles of a glass batch in one- and two-component systems under periodic physical impact on the storage tanks has been studied using model systems. It has been established that soda particles are concentrated in the upper layers of the batch, while sand particles are accumulated at the bottom. The fixation effects of dolomite particles when moistened with water, soda and potash solutions have been investigated. It has been revealed that, in contrast with the distribution of dry dolomite powder particles of different sizes, segregation reduces due to the capillary and capillary-crystallization interaction of disperse particles as there appear liquid interlayers.

The paper is concerned with the physicochemical processes of ion-electron interactions at the metal-oxide melt boundary during enamel coating formation. During the burning process on some spots on the surface of steel samples coated with enamel melt, there appear areas of intense metal oxidation with pronounced dark coloration in air atmosphere. It has been established that if in that place the melt is enriched with variable valence oxides to the extent that it becomes an electric conductor, the oxidation process is distributed in enamel melt at a constant rate over the entire metal surface. The speed at which the oxidation process spreads is determined by viscosity and composition of the melt. The paper presents the results of a study on the layer of metal-oxide melt adhesion using SEM.

The paper is aimed at determining the processes involved in the formation of an enamel slip structure during the slip drying stage. Using model systems, we have measured the capillary-crystallization forces of solid particles interaction through liquid interlayers of an enamel slip and its filtrates. The transition from frit solid components connected with liquid interlayers to “biscuit” during enamel slip drying has been discussed. When liquid evaporates from water suspension, the slip volume decreases, and isolated capillary bridges appear. Capillary layers cause structure compaction due to the impact on enamel frit particles. The evaporation of liquid results in the formation of crystal aggregates fixing solid particles. The differing behavior of particles is caused by the change in the composition of contact liquid.

High-lime fly ash (HLFA) obtained from the burning of coal at thermal power stations (TPS) consisting of free CaO can be regarded as a specific class of binding materials as they possess hydraulic activity and harden by forming stone of different hardness. This work is devoted to the study of the mechanisms of the chemical and mineralogical composition of high-lime fly ash formation depending on the industrial way of burning Siberian brown coal. Physical properties, chemical and mineralogical composition, and the hydraulic activity of 16 proper samples of HLFA were investigated: six samples of them were obtained at the Siberian TPS when burning brown coals by a flame burner, and four samples were obtained as a result of the experimental burning of brown coals at the commercial pilot plant with a circular fluidized bed. In addition to experimental research methods, the analysis of the CaO-Al₂O₃–SiO₂ state diagram and the calculation of the Gibbs energy for the estimation of the most probable reactions of phase composition of HLFA formation were performed.

It has been determined that free lime present in low temperature fly ashes obtained by burning in the furnaces with a circular fluidized bed is the product of carbonates of various nature decomposition according to its origin and in all other cases – the product of secondary sulfates decomposition.

A new method of hot-rolled pipes rolling on the automatic mill “tandem” is suggested. It consists of two rolling stands. This method allows one to achieve the rough pipe preovalisation before reaching the automatic mill. The rough pipe preovalisation provides even groove filling and the decrease of pipe wall thickness variation. Rough pipe preovalisation will allow us to increase the elongation ratio from 1.5 to 2.0 on the lengthwise rolling stand № 1 and to decrease the elongation ratio on the piercing mill. Therefore the chance of rolling skin formation on the external surface of pipe is decreased. The way to reduce the probability of the formation of a “guide mark” defect due to the kinematic tension during rolling on a stub mandrel with rough tube preovalisation is investigated. The influence of the kinematic tension factor on the pipe forming in the groove taper at a lengthwise rolling with rough tube preovalisation is explored.

The oil industry of Russia currently needs innovative development projects intended for a radical improvement of the performance of material resources and a decrease of their consumption. One of the most promising trends in corrosion protection is the production and use of pipes made of laminated composite materials. There are several principal ways of producing them by metal forming processes. World practice shows that lining technology is reasonable for oil well tubing. Lining consists of simultaneous expansion of pipes made of dissimilar materials, which possess different properties. A pipe of the kind manages to combine high corrosion resistance and mechanical strength, and this makes its service life more than four times higher than that of pipes made by conventional methods. However, previous foreign experience of manufacturing and using these pipes prompts the necessity of improving some pipe-making processes. This paper discusses new engineering solutions in the production of lined pipes, as well as in situ testing results.

This paper presents the drawbacks of tube cold deformation classical processes such as drawing through stationary dies and cold rolling by rolls and rollers. Large assortments of cold-deformed tubes are produced by these methods. In order to increase their quality, several improvements of cold deformation methods have been suggested. At the first stage, finite-element models for tubes produced by cold drawing and rolling were developed, and regression models were prepared for the dependence between the tube wall thickness variation and the process variables. Based on that, a new formula was developed for optimal grooving parameters. It allowed reducing the loading and longitudinal thickness variation of produced tubes. Finally, in order to correct the thickness variation for conventional methods, the preliminary grading on the profiled mandrels was proposed.

Analysis of stamping of platinum glass melting apparatus elements is carried out. It is revealed that the present technology of stamping leads to asymmetric filling of holes of the stamp. The problem of stamping is solved by the finite element method using software DEFORM-3D. The deformable metal is presented as an elastic-plastic medium. The deformation zone is limited by upper and lower dies. The upper die is a plate with rounded edges. The lower die is made with holes to be filled with metal. The workpiece is placed between the upper and lower dies. Moving of the upper die causes the deformation of the platinum alloy workpiece. Two approaches to improve the technology are considered. Firstly, it is proposed to change the step of stamping. For a small step, the metal plastic flow is asymmetrical, which distorts the profile of the projections on the workpiece. Therefore, it is proposed to increase the stamping step size. Secondly, it is proposed to change the rounding radius of the upper die edges. A larger radius of rounding facilitates the metal flow along the length of the workpiece, which hampers the filling of holes in the die. Therefore, it is proposed to reduce the rounding radius of the upper die edges. Computer modeling has confirmed the correctness of the recommendations.

Oil country tubular goods (OCTG) are widely used in the oil and gas industry. In order to increase joint efficiency of oil country tubular goods, the process for upsetting their ends is applied. However, the weakness of this upsetting technology is a frequent defect creation on the inner surface of the final product. These imperfections are surface breakings that reduce the effective pipe wall thickness; they are detected close to the upset ends of the pipe. Computer simulation and a full-scale experiment were used to study this defect nucleation. According to this research, the occurrence of defects is correlated with average pipe wall thickness, nonuniform wall thickness of the blank, heating mode, and friction conditions. The results of a full-scale experiment confirm the main conclusions made in the course of the finite element simulation. The research results define the interdependence of actual size of the blank and the operating tool calibration.

This paper presents the results of studies on residual stresses and surface hardening caused by finishing operations (boring and grinding a hot-rolled pipe billet, cold rolling middle-sized pipes, heating, rolling final-sized pipes, straightening, electropolishing the inner surface and burnishing the outer surface) and shows the need for exceptions to the production techniques for heat-exchanger pipes.