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A better understanding of phosphorus distribution in slag is necessary to develop an effective way to treat dephosphorization slag formed during steelmaking. Here, previous studies on the enrichment, separation, and recovery of phosphorus from dephosphorization slag are reviewed, along with their influencing factors. The results suggest that a proper heat treatment can promote the selective enrichment and growth of P-rich phases. Further, adding P2O5 and FetO facilitates phosphorus enrichment. Also, Ca3(PO4)2 is precipitated from slag containing 18 wt% P2O5. MnO and MgO in the slag barely affect the phosphorus recovery. In contrast, the addition of Al2O3 and TiO2 significantly affects phosphorus enrichment and magnetic separation. A phosphorus recovery rate of more than 70% is achieved with the addition of 10 wt% Al2O3 or 10 wt% TiO2. New phases (Na2Ca4(PO4)2SiO4, Na3PO4, and Ca5(PO4)3F) tend to be formed on the addition of Na2O and CaF2, which promote phosphorus enrichment. However, the addition of Na2O and CaF2 results in the incomplete separation of phosphorus and iron, as CaF2 and Na2O improve slag metallization and the magnetism of iron-rich phases.
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The functionality of a prosthesis is determined by clinical procedures, the manufacturing technology applied, the material used and its strength parameters. The aim of the paper is to evaluate the static strength and fatigue strength of acrylic construction materials directly after the process of polymerisation and for aged materials. It has been confirmed that the deformation speed of the tested materials has an evident impact on their mechanical characteristics. With greater deformation speed, a consistent increase in the material elasticity was observed in static compression tests, which was accompanied by a reduction in engineering stresses at the final stage of deformation. The greatest fatigue strength was observed for Vertex. It was by about 33% greater than the strength of Villacryl – the material that has the lowest fatigue properties. The resistance of acrylic polymers to cyclic loading applied with the frequency of 1 Hz may become an indication for the selection of the material to be used in the clinical procedures in which a patient is provided with full dentures.
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Commercially pure titanium is less expensive, generally more corrosion resistant and lower in strength than its alloys, and is not heat-treatable. The use of Ti and its alloys as construction materials under severe friction and wear conditions is limited due to their poor tribological properties. Nevertheless, proper addition of hard ceramic particles into Ti and its alloys has proved to be an efficient way to enhance their mechanical and wear properties. Our purpose in this work was to analyze the corrosion, tribocorrosion, mechanical and morphological effects of combining titanium carbide with titanium metal, to create a unique composite via spark plasma sintering technique (SPS). Composites with different mass percentage (1, 5, 10, 15 and 20 wt %) of ceramic phase were produced. The samples of pure Ti and Ti-6Al-4V alloy were also tested, as a reference. These composites were examined for mechanical properties and corrosion resistance in an environment similar to the human body (Ringer’s solution). Open circuit potential (OPC) and anodic polarization measurements were performed. The properties of titanium composites reinforced with micro- and nanocrystalline TiC powders were compared. It was stated that wear properties were significantly improved with increasing amount of TiC in matrix, especially in the case of nanocrystalline reinforcement. In terms of corrosion resistance, the composites showed slightly worse properties compared to pure titanium and Ti-6Al-4V alloy.
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New graphite tools were designed and produced to fabricate a semi-finished product from which nine cutting inserts were obtained in one spark plasma sintering process. As a result, WC-5Co cemented carbides were spark plasma sintered and the effect of various sintering parameters such as compacting pressure, heating rate and holding time on the main mechanical properties were investigated. It was shown that WC-5Co cemented carbides spark plasma sintered at 1200°C, 80 MPa, 400°C/min, for 5 min are characterized by the best relation of hardness (1861 ±10 HV30) and fracture toughness (9.30 MPa·m1/2). The microstructure of these materials besides the WC ceramic phase and Co binder phase consists of a synthesized Co3W3C complex phase. Comparison with a commercial WC-6Co cutting insert fabricated by conventional powder metallurgy techniques shows that spark plasma sintering is a very effective technique to produce materials characterized by improved mechanical properties.
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This research paper shows the influence of a repeated SPD (Severe Plastic Deformation) plastic forming with the DRECE technique (Dual Rolls Equal Channel Extrusion) on hardening of low carbon IF steel. The influence of number of passes through the device on change of mechanical properties, such as tensile strength TS and yield stress YS, of tested steel was tested. The developed method is based on equal channel extrusion with dual rolls and uses a repeated plastic forming to refinement of structure and improve mechanical properties of metal bands [1-2]. For the tested steel the increase of strength properties after the DRECE process was confirmed after the first pass in relation to the initial material. The biggest strain hardening is observed after the fourth pass.
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The article presents the results of investigations performed on segregation of elements in the billets. The research were performed under standard industrial conditions, during high carbon steel production cycle. Probes (templates with the thickness of 20 mm) were taken from billets with square cross-section of 160 mm. Segregation of elements was determined based on the quantitative analysis of results performed by using spark spectrometry pursuant to PN-H-04045. Changes in concentrations of elements were analysed along two cross-sections. Element contents were performed at points distanced from each other by approx. 10 mm. The segregation of carbon, sulphur and phosphorus was determined for different billets.
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The main purpose of the present work was to validate the numerical model for the pulse-step liquid steel alloying method using a physical simulator that enables the observation and recording of phenomena occurring during the continuous steel casting process. The facility under investigation was a single-nozzle tundish equipped with a dam. To physical trials the glass water model was made on a scale of 2:5. For the mathematical description of turbulence during liquid steel alloying process, the k-ε and k-ω models were employed in the simulations. Based on the computer simulations and physical trials carried out, alloy addition behaviour and mixing curves for different tundish alloy addition feeding positions were obtained. The change in the location of alloy addition feeding to the liquid steel had an effect on the process of alloy addition spread in the liquid steel bulk and on the mixing time.
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The sintered stainless steels of different microstructures (austenitic, ferritic and duplex) were laser surface alloyed with hard powders (SiC, Si3N4) and elemental alloying powders (Cr, FeCr, FeNi) to obtain a complex steel microstructure of improved properties. Laser surface alloying (LSA) involved different strategies of powder placing: the direct powder feeding to the molten metal pool and filling grooves machined on the sample surface by powder, and then laser surface melting. Obtained microstructures were characterised and summarised, basing on LOM, SEM and XRD analysis. The links between base material properties, like superficial hardness and microhardness, derived microstructures and erosion resistance was described. The LSA conditions and alloying powder placement strategies on erosion resistance was evaluated. The erosion wear is lower for Cr, FeCr, FeNi laser alloying, where powders were dissolved in the steel microstructure, and hard phases were not precipitated. Precipitations of hard phases (carbides, silicides, martensite formation) reduce erosion resistance of SiC alloyed stainless steel. The LSA with Si3N4 works better due to lack of precipitates and formation of a soft and ductile austenitic microstructure. The erosion wear at the impingement angle of 90° is high for hard and therefore brittle surface layers obtained as a result of alloying by hard particles (SiC, Si3N4). The softer and ductile austenitic stainless steel resist better than harder ferritic and duplex stainless steel material at studied erodent im pingement angle.
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This paper shows results of researches of a structure and mechanical properties of metal sheets of IF steels subjected torecrystallization annealing. The annealing was held in the scope of the temperature of 600-900°C over 25 min time. The impact of heat treatment on changes of properties and structure of the researches steel has been analysed. During annealing typical processes of rebuilding of the structure deformed as a result of cold deformation in the form of forming new recrystallized grains and their growth were observed. As the temperature of annealing increases the hardness of the material gradually decreases.
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In the paper, on the basis of the performed tests, low-cycle fatigue characteristics (LCF) of selected light metal alloys used among others in the automotive and aviation industries were developed. The material for the research consisted of hot-worked rods made of magnesium alloy EN-MAMgAl3Zn1, two-phase titanium alloy Ti6Al4V and aluminium alloy AlCu4MgSi(A). Alloys used in components of means of transport should have satisfactory fatigue, including low-cycle fatigue, characteristics. Low-cycle fatigue tests were performed on an MTS-810 machine at room temperature. Low-cycle fatigue tests were performed for three total strain ranges Δεt = 0.8%, 1.0% and 1.2% with a cycle asymmetry coefficient R = –1. On the basis of the obtained results, characteristics of the fatigue life of materials, cyclic deformation σa = f(N) and cyclic deformation of the tested alloys were developed. The tests showed that titanium alloy Ti6Al4V was characterised by the highest fatigue life Nf, whereas the lowest fatigue life was found in the tests of the aluminium alloy AlCu4MgSi(A).
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The paper analyzes the effect of ageing on the variations in the mechanical and technological properties of steel wire. The process of drawing 5.5 mm-diameter wire rod into 1.70 mm wire was carried out in 12 draws on a Koch KGT multi-stage drawing machine in the drawing velocity range of 5-25 m/s. Finished 1.7 mm-diameter wires after, respectively, 1, 24, 720 and 8760 hours of the completion of the drawing process were subjected to testing to determine their mechanical and technological properties. The yield strength, YS; tensile strength, UTS; uniform elongation, Ar; total elongation, Ac; reduction of area, Z; number of twists, Nt; and the number of bends, Nb, have been determined. It has been demonstrated that variations in mechanical properties occur after the multi-stage drawing process due to ageing, with their degree and mode being dependent on the drawing speed.
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The paper presents the results of the effect of isothermal heating time on the disappearance of strain hardening (the softening degree) of the studied high-manganese TRIPLEX type steels at a temperature of 900 and 1000°C. In order to determine the kinetics of recrystallization of austenite plastically deformed for selected steels, hot compression tests with draft ε = 0.2 were made. The presented results reveal that the complete recrystallization of austenite needs long isothermal heating times. In industrial conditions, such long times are not used, therefore in the initial rolling passages, the time required for half recrystallization of austenite t0.5 is often used. The total disappearance of the strain hardening, completion of the recrystallization of austenite tested high-manganese X98 and X105 TRIPLEX type steels isothermal heating time requires far more than 200 s. The increase of the deformation temperature is a factor influencing the acceleration of the disappearance of strain hardening.
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The behaviour of porous sinters, during compression and compression with reverse cyclic torsion tests is investigated in the article based on the combination of experimental and numerical techniques. The sinters manufactured from the Distaloy AB powder are examined. First, series of simple uniaxial compression tests were performed on samples with three different porosity volume fractions: 15, 20 and 25%. Obtained data were then used during identification procedure of the Gurson-Tvergaard-Needleman finite element based model, which can capture influence of porosity evolution on plasticity. Finally, the identified Gurson-Tvergaard- Needleman model was validated under complex compression with reverse cyclic torsion conditions and proved its good predictive capabilities. Details on both experimental and numerical investigations are presented within the paper.
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The article shows a new model of Continuous Cooling Transformation (CCT) diagrams of structural steels and engineering steels. The modelling used artificial neural networks and a set of experimental data prepared based on 550 CCT diagrams published in the literature. The model of CCT diagrams forms 17 artificial neural networks which solve classification and regression tasks. Neural model is implemented in a computer software that enables calculation of a CCT diagram based on chemical composition of steel and its austenitizing temperature.
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The paper presents the results of laboratory tests into the effects of moisture and the content of two types of bentonite on dielectric properties of moulding sand. The use of electromagnetic waves in foundry industry is becoming more and more popular, which provides to some extent alternatives to conventional drying methods. Experimental studies published so far have shown the validity of using microwaves for drying classic moulding sands with bentonite. However, these studies lack data on the effect of moisture or bentonite content in moulding sand on the real component ε' or imaginary component ε'' of the relative complex electrical permittivity. The presented results may become in the future the basis for the evaluation of the composition of moulding sands, taking into account the phenomena occurring under the influence of electromagnetic field, which directly translates into the quality of the castings made and may constitute an attempt to develop a mathematical model of electric properties of moulding sands.
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The paper presents the results and provides an analyse of the geometric structure of Fe-Al protective coatings, gas-treated under specified GDS conditions. The analysis of the surface topography was conducted on the basis of the results obtained from the SEM data. Topographic images were converted to three-dimensional maps, scaling the registered amplitude coordinates of specific gray levels to the relative range of 0÷1. This allowed us to assess the degree of surface development by determining the fractal dimension. At the same time, the generated three-dimensional spectra of the autocorrelation function enabled the researchers to determine the autocorrelation length (Sal) and the degree of anisotropy (Str) of the surfaces, in accordance with ISO 25178. Furthermore, the reconstructed three-dimensional images of the topography allowed us to evaluate the functional properties o the studied surfaces based on the Abbott-Firestone curve (A-F), also known as the bearing area curve. The ordinate describing the height of the profile was replaced by the percentage of surface amplitude in this method, so in effect the shares of the height of the three-dimensional topographic map profiles of various load-bearing properties were determined. In this way, both the relative height of peaks, core and recesses as well as their percentages were subsequently established.
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Currently is the biggest problem of metallurgical companies the increase of fossil fuel prices and strict environmental regulations. As a result of this, companies must look for alternatives that would reduce the amount of fossil fuels and reduce emissions. Wood sawdust has huge energy potential, which can be used in the process of agglomerate production. This type of energy is locally available, has some similar properties as fossil fuels and is economically advantageous. For these reasons, experimental study using laboratory agglomeration pan was realized to study the possibility of agglomerate production with a mixed fuel. Experimental results show the viability of mixed fuel use in the agglomeration process, but also show significant possibility for improvement. The maximum acceptable substitution ratio, which corresponds to qualitatively suitable agglomerate is 20% of pine sawdust. Based on the realized experiments and the obtained results we have acceded to the intensification of the agglomeration process with an objective to increase the amount of added substitution fuel while maintaining the required quality of agglomerate.
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The rolls for the hot rolling finishing stands are cast centrifugally as two or three-layer rolls. The working layer is called a shell. The material of the shell is selected according to the position of the respective roll in the final finishing stand of the rolling mill. Typically, a combination of rolls made of a high-chromium cast iron + indefinite cast iron or high-speed steel + indefinite cast iron is commonly used. Great attention has been paid to indefinite cast iron in recent years and this material received a number of modifications that led to the increase of material properties up to 20% in comparison to the ordinary indefinite cast iron. But the goals of the new generation of material for hot rollers were chosen higher: increasing of production about 30% and more. This material has specific physical properties, heat treatment requirements as well as rolling mill requirements as is stated in the paper. It is expected that introduction of this material will reduce the difference between wear of the front and finishing stands, which can extend rolling campaigns and have a positive effect on the reduction rolls exchanges, the grinding of the rolls and the reduction of downtime.
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Internal structure of metal foams is one of the most important factors that determine its mechanical properties. There exists a number of methods for studying the nature of the inner porous structure. Unfortunately most of these processes is destructive and therefore it is not possible to reuse the sample. From this point of view, as a suitable method seems to be the ability of using the so-called X-ray microtomography (also micro-CT). This is a non-destructive methodology used in a number of fields (industry, science, archaeology, medicine) for a description of the material distribution in the space (e.g. pores, fillers, defects, etc.). In principle, this technology works on different absorption of X-ray radiation by materials with changing proton number. The contribution was worked out in collaboration with experts from the Faculty of Electrical Engineering and Computer Science of the VŠB-Technical University of Ostrava and it is focused on the analysis of internal structure of the metal foam casting with irregular arrangement of internal pores by using micro-CT. The obtained data were evaluated in the commercial software VGStudio MAX 2.2 and in the FOTOMNG system. For the evaluation of these data a new specialized module was introduced in this system. Several methods of pre-processing the image was prepared for the measurement. This preliminary processing consists, for example, from a binary image thresholding for better diversity between the internal porosity and the material itself or functions for colour inversion.
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Main aim of submitted work is evaluation and experimental verification of inoculation effect on Al alloys hot-tear sensitivity. Submitted work consists of two parts. The first part introduces the reader to the hot tearing in general and provides theoretical analysis of hot tearing phenomenon. The second part describes strontium effect on hot tearing susceptibility, and gives the results on hot tearing for various aluminium alloys. During the test, the effect of alloy chemical composition on hot tearing susceptibility was also analyzed. Two different Al-based alloys were examined. Conclusions deals with effect of strontium on hot tearing susceptibility and confirms that main objective was achieved.
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Experimental observations of the steel morphology as well as measurements of the solutes concentration in the macro-scale were made on the basis of the vertical cut at the mid-depth of the 15-tons steel forging ingot serially produced in one of the steel plant in Poland. Experimental observations of the morphology accompanied by the measurements of the Peclet Number were also made on the cross-section of the continuously cast brass ingots serially produced in the copper / brass industry in Poland. The performed measurements allowed to work out some maps of the alloying elements segregation for the longitudinal section of the steel static ingot and a Growth Law for the columnar grains formation in the brass ingots. The marginal stability criterion has been applied to the last mentioned development / description. Some suggestions for the micro-segregation measurement mode in the columnar structure are derived.
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Detailed studies of the movement of liquid steel (hydrodynamics) on a real object are practically impossible. The solution to this problem are physical modelling carried out on water models and numerical modelling using appropriate programs. The method of numerical modelling thanks to the considerable computing power of modern computers gives the possibility of solving very complex problems. The paper presents the results of model tests of liquid flow through tundish. The examined object was model of the twonozzle tundish model. The ANSYS Fluent program was used to describe the behavior of liquid in the working area of the tundish model. Numerical simulations were carried out using two numerical methods of turbulence description: RANS (Reynolds-Averaged Navier-Stokes) – model k-ε and LES (Large Eddy Simulation). The results obtained from CFD calculations were compared with the results obtained using the water model.
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The subject of the study are alumina foams produced by gelcasting method. The results of micro-computed tomography of the foam samples are used to create the numerical model reconstructing the real structure of the foam skeleton as well as the simplified periodic open-cell structure models. The aim of the paper is to present a new idea of the energy-based assessment of failure strength under uniaxial compression of real alumina foams of various porosity with use of the periodic structure model of the same porosity. Considering two kinds of cellular structures: the periodic one, for instance of fcc type, and the random structure of real alumina foam it is possible to justify the hypothesis, computationally and experimentally, that the same elastic energy density cumulated in the both structures of the same porosity allows to determine the close values of fracture strength under compression. Application of finite element computations for the analysis of deformation and failure processes in real ceramic foams is time consuming. Therefore, the use of simplified periodic cell structure models for the assessment of elastic moduli and failure strength appears very attractive from the point of view of practical applications.
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Single point incremental forming process is a most economical Die-less forming process. The major constraint of it is that it is a time consuming process. In this work, a new attempt was made in incremental forming process using Multipoint tool for SS430 sheets to increase the formability and to reduce forming time. Fractography analysis was made to study the size of voids that were formed during fracture. The forming limit diagrams were drawn and compared for single point incremental forming and the multipoint incremental forming of SS430 sheet. It was proved that the formability of SS430 sheet in the multipoint forming was better than the formability of that in single point forming and the time consumed was reduced. The strain distribution in both processes had also been studied along with surface roughness.
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