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Number of results: 140
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Abstract

Steel and cast-iron products, due to their low price and beneficial properties, are the most widely used among metals; their consumption has become an indicator of the economic development of countries. The characteristics of iron raw materials, in relation to current metallurgical requirements, are presented in the present this article. The globalization of the trade and development of steelmaking technologies have caused significant changes in the quality of raw materials in the last half-century forcing improvements in processing technologies. In many countries, standard concentrates (at least 60% Fe) are almost twice as rich as those processed in the mid-20th century. Methods of quality assessment have been improved and quality standards tightened. The quality requirements for the most important raw materials ‒ iron ores and concentrates, steel scrap, major alloy metals, coking coal, and coke, as well as gas and other energy media ‒ are reviewed in the present paper. Particular attention is paid to the quality testing methodology. The quality of many raw materials is evaluated multi-parametrically: both chemical and physical characteristics are important. Lower-quality parameters in raw materials equate to significantly lower prices obtained by suppliers in the market. The markets for these raw materials are diversified and governed by separate sets of newly introduced rules. Price benchmarks (e.g. for standard Australian metallurgical coal) or indices (for iron concentrates) apply. Some raw materials are quoted within the framework of the commodity market system (certain alloying components and steel scrap). The abandonment of the long-established system of multi-annual contracts has led to wide fluctuations in prices, which have reached a scale similar to that of other metals.
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Abstract

This article deals with the effect of manganese that is the most applied element to eliminate the negative effect of iron in the investigated alloy AlSi7Mg0.3. In this time are several methods that are used for elimination harmful effect of iron. The most used method is elimination by applying the additive elements, so-called iron correctors. The influence of manganese on the morphology of excluded ironbased intermetallic phases was analysed at various iron contents (0.4; 0.8 and 1.2 wt. %). The effect of manganese was assessed in additions of 0.1; 0.2; 0.4 and 0.6 wt. % Mn. The morphology of iron intermetallic phases was assessed using electron microscopy (SEM) and EDX analysis. The increase of iron content in investigated alloys caused the formation of more intermetallic phases and this effect has been more significant with higher concentrations of manganese. The measurements carried out also showed that alloys with the same Mn/Fe ratio can manifest different structures and characteristics of excluded iron-based intermetallic phases, which might, at the same time, be related to different resulting mechanical properties.
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Abstract

In this study, modification of the AZ91 magnesium alloy surface layer with a CO2 continuous wave operation laser has been taken on. The extent and character of structural changes generated in the surface layer of the material was being assessed on the basis of both macro- and microscopy investigations, and the EDX analysis. Considerable changes in the structure of the AZ91 alloy surface layer and the morphology of phases have been found. The remelting processing was accompanied by a strong refinement of the structure and a more uniform distribution of individual phases. The conducted investigations showed that the remelting zone dimensions are a result of the process parameters, and that they can be controlled by an appropriate combination of basic remelting parameters, i.e. the laser power, the distance from the sample surface, and the scanning rate. The investigations and the obtained results revealed the possibility of an effective modification of the AZ91 magnesium alloy surface layer in the process of remelting carried out with a CO2 laser beam.
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Abstract

The multiple direct remelting of composites based on the A359 alloy reinforced with 20% of Al2O3 particles was performed. The results of both gravity casting and squeeze casting were examined in terms of the obtained microstructure and mechanical characteristics. In microstructure examinations, the combinatorial method based on phase quanta theory was used. In mechanical tests, the modified low cycle fatigue method (MLCF) was applied. The effects obtained after both gravity casting and squeeze casting were compared. It was noted that both characteristics were gradually deteriorating up to the tenth remelting. The main cause was the occurrence of shrinkage porosity after the gravity casting. Much better results were obtained applying the squeeze casting process. The results of microstructure examinations and fatigue tests enabled drawing the conclusion that the A359 alloy reinforced with Al2O3 particles can confer a much better fatigue life behavior to the resulting composite than the A359 alloy without the reinforcement. At the same time, comparing these results with the results of the previous own research carried out on the composites based also on the A359 alloy but reinforced in the whole volume with SiC particles, it has been concluded that both types of the composites can be subjected to multiple remelting without any significant deterioration of the structural and mechanical characteristics. The concepts and advantages of using the combinatorial and MLCF methods in materials research were also presented
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Abstract

The main scope of the article is the development of a computer system, which should give advices at problem of cooper alloys manufacturing. This problem relates with choosing of an appropriate type of bronze (e.g. the BA 1044 bronze) with possible modification (e.g. calcium carbide modifications: Ca + C or CaC2) and possible heat treatment operations (quenching, tempering) in order to obtain desired mechanical properties of manufactured material described by tensile strength - Rm, yield strength - Rp0.2 and elongation - A5. By construction of the computer system being the goal of presented here work Case-based Reasoning is proposed to be used. Case-based Reasoning is the methodology within Artificial Intelligence techniques, which enables solving new problems basing on experiences that are solutions obtained in the past. Case-based Reasoning also enables incremental learning, because every new experience is retained each time in order to be available for future processes of problem solving. Proposed by the developed system solution can be used by a technologist as a rough solution for cooper alloys manufacturing problem, which requires further tests in order to confirm it correctness.
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Abstract

The paper deals with the impact of technological parameters on the heat transfer coefficient and microstructure in AlSi12 alloy using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. The pressure applied to the melt causes a significant increase of the coefficient of heat transfer between the melt and the mold. There is an increase in heat flow by approximately 50% and the heat transfer coefficient of up to 100-fold, depending on the casting conditions. The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometry with significantly shorter length occurs when used gravity casting method. By using the pressure of 150 MPa during the crystallization process, in the structure can be observed an irregular silica particles, but the size does not exceed 25 microns.
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Abstract

The results of structure and mechanical properties investigations of tungsten heavy alloy (THA) after cyclic sintering are presented. The material for study was prepared using liquid phase sintering of mixed and compacted powders in hydrogen atmosphere. The specimens in shape of rods were subjected to different number of sintering cycles according to the heating schemes given in the main part of the paper From the specimens the samples for mechanical testing and structure investigations were prepared. It follows from the results of the mechanical studies, that increasing of sintering cycles lead to decrease of tensile strength and elongation of THA with either small or no influence on yield strength. In opposite to that, the microstructure observations showed that the size of tungsten grain increases with number of sintering cycles. Moreover, scanning electron microscope (SEM) observations revealed distinctly more trans-granular cleavage mode of fracture in specimens subjected to large number of sintering cycles compared with that after one or two cycles only.
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Abstract

This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.
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Abstract

The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness. Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper, the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands. The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present paper.
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Abstract

The paper presents the results of simulation of alloy layer formation process on the model casting. The first aim of this study was to determine the influence of the location of the heat center on alloy layer’s thickness with the use of computer simulation. The second aim of this study was to predict the thickness of the layer. For changes of technological parameters, the distribution of temperature in the model casting and temperature changes in the characteristic points of the casting were found for established changes of technological parameters. Numerical calculations were performed using programs NovaFlow&Solid. The process of obtaining the alloy layer with good quality and proper thickness depends on: pouring temperature, time of premould hold at the temperature above 1300o C. The obtained results of simulation were loaded to authorial program Preforma 1.1 in order to determine the predicted thickness of the alloy casting
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Abstract

Titanium alloy (Ti-6Al-4V) has been extensively used in aircraft turbine-engine components, aircraft structural components, aerospace fasteners, high performance automotive parts, marine applications, medical devices and sports equipment. However, wide-spread use of this alloy has limits because of difficulty to machine it. One of the major difficulties found during machining is development of poor quality of surface in the form of higher surface roughness. The present investigation has been concentrated on studying the effects of cutting parameters of cutting speed, feed rate and depth of cut on surface roughness of the product during turning of titanium alloy. Box-Behnken experimental design was used to collect data for surface roughness. ANOVA was used to determine the significance of the cutting parameters. The model equation is also formulated to predict surface roughness. Optimal values of cutting parameters were determined through response surface methodology. A 100% desirability level in the turning process for economy was indicated by the optimized model. Also, the predicted values that were obtained through regression equation were found to be in close agreement to the experimental values.
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Abstract

The paper describes the studies of ternary SnZn9Al1.5 lead-free alloy from the viewpoint of its mechanical behavior as well as microstructure examined by the light and scanning electron microscopy. The authors focused their attention specifically on the fatigue parameters determined by the original modified low-cycle fatigue method (MLCF), which in a quick and economically justified way allows determination of a number of mechanical parameters based on the measurement data coming from one test sample only. The effect of the addition of 1.5% Al to the binary eutectic SnZn9 alloy on its microstructure and the obtained level of mechanical parameters was analyzed. The phases and intermetallic compounds occurring in the alloy were identified based on the chemical analysis carried out in micro-areas by the SEM/EDS technique. It was shown that the addition of 1.5% Al to the binary eutectic SnZn9 alloy resulted in a more favorable microstructure and consequently had a positive effect on the mechanical parameters of the alloy. Based on the conducted research, it was recommended to use a combinatorial method based on the phase quanta theory to quickly evaluate the microstructure and the original MLCF method to determine a number of mechanical parameters.
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Abstract

The results of studies presented in this article are an example of the research activity of the authors related to lead-free alloys. The studies covered binary SnZn90 and SnZn95 lead-free alloys, including their microstructure and complex mechanical characteristics. The microstructure was examined by both light microscopy (LM) and scanning electron microscopy (SEM). The identification of alloy chemical composition in micro-areas was performed by SEM/EDS method. As regards light microscopy, the assessment was of both qualitative and quantitative character. The determination of the geometrical parameters of microstructure was based on an original combinatorial method using phase quantum theory. Comprehensive characterization of mechanical behavior with a focus on fatigue life of alloys was performed by means of the original modified low cycle fatigue method (MLCF) adapted to the actually available test machine. The article discusses the fatigue life of binary SnZn90 and SnZn95 alloys in terms of their microstructure. Additionally, the benefits resulting from the use of the combinatorial method in microstructure examinations and MLCF test in the quick estimation of several mechanical parameters have been underlined.
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Abstract

The study involved using the liquid-solid compound casting process to fabricate a lightweight ZE41/AlSi12 bimetallic material. ZE41 melt heated to 660 oC was poured onto a solid AlSi12 insert placed in a steel mold. The mold with the insert inside was preheated to 300 oC. The microstructure of the bonding zone between the alloys was examined using optical microscopy and scanning electron microscopy. The chemical composition was determined through linear and point analyses with an energy-dispersive X-ray spectroscope (EDS). The bonding zone between the magnesium and aluminum alloys was about 250 μm thick. The results indicate that the microstructure of the bonding zone changes throughout its thickness. The structural constituents of the bonding zone are: a thin layer of a solid solution of Al and Zn in Mg and particles of Mg-Zn-RE intermetallic phases (adjacent to the ZE41 alloy), a eutectic region (Mg17(Al,Zn)12 intermetallic phase and a solid solution of Al and Zn in Mg), a thin region containing fine, white particles, probably Al-RE intermetallic phases, a region with Mg2Si particles distributed over the eutectic matrix, and a region with Mg2Si particles distributed over the Mg-Al intermetallic phases matrix (adjacent to the AlSi12 alloy). The microstructural analysis performed in the length direction reveals that, for the process parameters tested, the bonding zone forming between the alloys was continuous. Low porosity was observed locally near the ZE41 alloy. The shear strength of the AZ91/AlSi17 joint varied from 51.3 to 56.1 MPa.
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Abstract

In this work, the effect of the microstructure on corrosion behavior of selected Mg- and Al-based as cast alloys, was evaluated. The electrochemical examinations were carried out, and then a morphology of corrosion products formed due to local polarization on materials surface, was analyzed. It was documented that the presence of Mg2Si phase plays an important role in the corrosion course of Mg-based alloy. A selective etching was observed in sites of Mg2Si precipitates having “Chinese script”- like morphology. Analogous situation was found for Al-based alloy, where the key role was played by cathodic θ-CuAl2 phase.
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Abstract

The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. The influence of process parameters variation (casting temperature, mold temperature, pressure) on mechanical properties and structure will be observed. The thicknesses of the individual walls were selected based on the use of preferred numbers and series of preferred numbers (STN ISO 17) with the sequence of 3.15, 4.00, 5.00, 6.00 and 8.00 mm. The width of each wall was 22 mm with a length of 100 mm. As an experimental material was chosen the AlSi12 and AlSi7Mg0.3 alloys. The mechanical properties (UTS, E) for individual casting parameters and their individual areas of different thicknesses were evaluated. In the structure the influence of pressure on the change of the eutectic morphology, the change of the volume of eutectic and the primary alpha phase, the effect of the pressure on the more fine-grain and the regularization of the structure were evaluated.
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Abstract

The paper presents the research results of the solenoid housing made of the Zn4Al1Cu alloy that was destroyed as a result of corrosion. Surface of the tested part showed macroscopically the features typical for white corrosion, and the resulting corrosion changes led to a disturbance of the alloy cohesion. The research performed have shown that the tested solenoid valve has intergranular corrosion as a reaction of the environment containing road salt. The corrosion was initiated in the areas of the alfa phase existence appearing in the eutectic areas which propagated over dendritic areas of the alloy. Initiation of the corrosion followed as a result of the galvanic effect of the alfa phase reach in aluminium showing higher electrochemical potential, in contact with the eta phase reach in zinc. The impact of the phase reach in lead present in the microstructure on the corrosion processes run was not found.
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Abstract

The paper presents an analysis of the effect of shape of primary silicon crystals on the sizes of stresses and deformations in a surface layer of A390.0 alloy by Finite Elements Method (FEM). Analysis of stereological characteristics of the studied alloy, performed based on a quantitative metallographic analysis in combination with a statistical analysis, was used for this purpose. The presented simulation tests showed not only the deposition depth of maximum stresses and strains, but also allowed for determining the aforementioned values depending on the shape of the silicon crystals. The studied material is intended for pistons of internal combustion engines, therefore the analysis of the surface layer corresponded to conditions during friction in a piston-cylinder system of an internal combustion engine having power of up to 100 kW. The obtained results showed important differences in the values of stresses and strains up to 15% between various shape of the silicon crystals. Crystals with sharp edges caused higher stresses and deformation locally than those with rounded shapes.
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Abstract

In order for the working status of the aluminum alloyed hydraulic valve body to be controlled in actual conditions, a new friction and wear design device was designed for the cast iron and aluminum alloyed valve bodies comparison under the same conditions. The results displayed that: (1) The oil leakage of the aluminum alloyed hydraulic valve body was higher than the corresponding oil leakage of the iron body during the initial running stage. Besides during a later running stage, the oil leakage of the aluminum alloyed body was lower than corresponding oil leakage of the iron body; (2) The actual oil leakage of different materials consisted of two parts: the foundation leakage that was the leakage of the valve without wear and wear leakage that was caused by the worn valve body; (3) The aluminum alloyed valve could rely on the dust filling furrow and melting mechanism that led the body surface to retain dynamic balance, resulting in the valve leakage preservation at a low level. The aluminum alloy modified valve body can meet the requirements of hydraulic leakage under pressure, possibly constituting this alloy suitable for hydraulic valve body manufacturing.
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Abstract

The paper deals with the impact of technological parameters on the mechanical properties and microstructure in AlSi12 alloy using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. From the experiments we can conclude that operating pressure of 100 MPa is sufficient to influence the structural characteristics of the alloy AlSi12. The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. At a pressure of 100 MPa was increased of tensile strength on average of 20%. At a pressure of 150 MPa was increased of tensile strength on average of 30%. During the experiment it was also observed, that increasing difference between the casting temperature and the mold temperature leads to increase of mechanical properties.
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Abstract

Inconel 713C is a nickel-based casting alloy characterised by improved heat and creep resistance [1]. It is used e.g. in aircraft engine components, mainly in the form of precision castings. Precision casting enables very good reproduction of complex shapes. However, due to major differences in casting wall thickness and the resultant differences in rigidity, defects can form in precision castings. The most common defects in precision castings are shrinkage porosities and microcracks. Inconel 713C is considered to be a difficult-to-weld or even non-weldable alloy. However, the need to repair precision castings requires attempts to develop technologies for their remelting and pad welding which could be used in industrial practice. This article presents the results of tests consisting in TIG pad welding of defects identified in precision castings intended for the aircraft industry. It was found that the main reason behind failed attempts at repairing precision castings by welding technologies was hot cracking in the fusion zone. Such cracks form as a result of the partial melting of intercrystalline regions along the fusion line. The deformations occurring during the crystallization of the melting-affected zone (fusion zone + partially melted zone + heat affected zone) or pad weld lead to the rupture of the intercrystalline liquid film. Hot cracks form within the so-called high-temperature brittleness range (HTBR) of the alloy. Another type of cracks that was identified were ductility dip cracks (DDC), whose formation is related to the partial melting of carbides.
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Abstract

In order to study the effects of various gating systems on the casting of a complex aluminum alloyed multi-way valve body, both software simulation analysis and optimization were carried out. Following, the aluminum alloyed multi-way valve body was cast to check the pouring of the aluminum alloy valve body. The computer simulation results demonstrated that compared to the single side casting mode, the casting method of both sides of the gating system would reduce the filling of the external gas, while the air contact time would be lower. Adversely, due to the pouring on both sides, the melt cannot reach at the same time, leading to the liquid metal speed into the cavity to differ, which affected the liquid metal filling stability. The riser unreasonable setting led to the solidification time extension, resulting in a high amount of casting defects during solidification. Also, both gating systems led the entire casting inconsequential solidification. To overcome the latter problems, a straight gate was set at the middle pouring and the horizontal gate diversion occurred on both sides of pouring, which could provide better casting results for the aluminum alloyed multi-valve body.
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Abstract

To the main advantages of magnesium alloys belongs their low density, and just because of such property the alloys are used in aviation and rocket structures, and in all other applications, where mass of products have significant importance for conditions of their operation. To additional advantages of the magnesium alloys belongs good corrosion resistance, par with or even surpassing aluminum alloys. Magnesium is the lightest of all the engineering metals, having a density of 1.74 g/cm3 . It is 35% lighter than aluminum (2.7 g/cm3 ) and over four times lighter than steel (7.86 g/cm3 ). The Mg-Li alloys belong to a light-weight metallic structural materials having mass density of 1.35-1.65 g/cm3 , what means they are two times lighter than aluminum alloys. Such value of mass density means that density of these alloys is comparable with density of plastics used as structural materials, and therefore Mg–Li alloys belong to the lightest of all metal alloys. In the present paper are discussed melting and crystallization processes of ultra-light weight MgLi12,5 alloys recorded with use of ATND methods. Investigated magnesium alloy was produced in Krakow Foundry Research Institute on experimental stand to melting and casting of ultra-light weight alloys. Obtained test results in form of recorded curves from ATND methods have enabled determination of characteristic temperatures of phase transitions of the investigated alloy.
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Abstract

The paper presents the influence of modification with phosphorus (CuP10) on the tribological properties of the alloy AlSi17Cu5Mg coupled abrasively with cast-iron EN GJL-350. Tests of coefficient of friction and wear of mass were conducted on tribological tester T-01. An important aspect in the assessment of the tribological properties is the analysis of initial material microstructure in reference to silumin which underwent modification with phosphorus. It was found that the difference in structure of tested materials, mainly sizes of primary silicon crystals significantly influences the tribological properties whereas the speed change of the friction knot does not have such big influence.
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Abstract

The results of some mechanical properties of four Mg-5Al-xRE-0.4Mn (x = 1 – 5) alloys are presented. The microstructure of experimental alloys consisted of an α-Mg phase and an α+γ semi-divorced eutectic, Al11RE3 phase and an Al10RE2Mn7 intermetallic compound. For gravity casting in metal mould alloys, Brinell hardness, impact strength, tensile and compression properties at ambient temperature were determined. The performed mechanical tests allowed the author to determine the proportional influence of the mass fraction of rare earth elements in the alloys on their tensile strength, yield strength, compression strength and Brinell hardness. The impact strength of the alloys slightly decreases with a rise in the rare earth elements mass fraction.
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