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Number of results: 66
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Abstract

The subject of the paper is structural stability of the Zn-26 wt.% Al binary alloys doped with 2.2 wt.% Cu or 1.6 wt.% Ti addition. The structural stability of Zn-Al alloys with increased Al content is connected with stability of solid solution of zinc in aluminium α', which is the main component of these alloys microstructure. Such a solution undergoes phase transformations which are accompanied, among others, by changes in dimensions and strength properties. The structural stability of the ZnAL26Cu2.2 and ZnAl26Ti1.6 alloys was investigated using XRD examinations during long term natural ageing after casting, as well as during long term natural ageing after super-saturation and quenching. On the basis of the performed examinations it was stated that small Ti addition to the binary ZnAl25 alloy, apart from structure refinement, accelerates decomposition of the primary α' phase giving stable structure in a shorter period of time in comparison with the alloy without Ti addition. Addition of Ti in amount of 1.6 wt.%, totally replacing Cu, allows obtaining stable structure and dimensions and allows avoiding structural instability caused by the metastable ε−CuZn4 phase present in the ZnAl26Cu2.2 alloy.
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Abstract

The paper is devoted to grain-refinement of the medium-aluminium zinc based alloys (MAl-Zn). The system examined was sand cast Zn10 wt. %. Al binary alloy (Zn-10Al) doped with commercial Al-3 wt. % Ti – 0.15 wt. % C grain refiner (Al-3Ti-0.15C GR). Basing on the measured attenuation coefficient of ultrasonic wave it was stated that together with significantly increased structure fineness damping decreases only by about 10 – 20%. The following examinations should establish the influence of the mentioned grain-refinement on strength and ductility of MAl-Zn cast alloys.
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Abstract

The paper presents relationships between the degree of structure fineness and feeding quality of the Al – 20 wt.% Zn (Al-20 Zn) alloy cast into a mould made from sand containing silica quartz as a matrix and bentonite as a binder, and its damping coefficient of the ultrasound wave at frequency of 1 MHz. The structure of the examined alloy was grain refined by the addition of the refining Al-3 wt.% Ti – 0.15 wt.%C (TiCAl) master alloy. The macrostructure analysis of the initial alloy without the addition of Ti and the alloy doped with 50-100 ppm Ti as well as results of damping experiments showed that the structure of the modified alloy is significantly refined. At the same time, its damping coefficient decreases by about 20-25%; however, it still belongs to the so called high-damping alloys. Additionally, it was found that despite of using high purity metals Al and Zn (minimum 99,99% purity), differences in the damping coefficient for samples cut from upper and bottom parts of the vertically cast rolls were observed. These differences are connected with the insufficient feeding process leading to shrinkage porosity as well as gases present in metal charges which are responsible for bubbles of gas-porosity.
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Abstract

Among the copper based alloys, Cu-Al-X bronzes are commonly used as mold materials due to their superior physical and chemical properties. Mold materials suffer from both wear and corrosion, thus, it is necessary to know which one of the competitive phenomenon is dominant during the service conditions. In this study, tribo-corrosion behavior of CuAl10Ni5Fe4 and CuAl14Fe4Mn2Co alloys were studied and electrochemical measurements were carried out using three electrode system in 3.5 % NaCl solution in order to evaluate their corrosion resistance. In tribo-corrosion tests, alloys were tested against zirconia ball in 3.5 % NaCl solution, under 10N load with 0.04 m/s sliding speed during 300 and 600 m. The results indicate that (i) CuAl10Ni5Fe4 alloy is more resistant to NaCl solution compared to CuAl14Fe4Mn2Co alloy that has major galvanic cells within its matrix, (ii) although CuAl10Ni5Fe4 alloy has lower coefficient of friction value, it suffers from wear under dry sliding conditions, (iii) as the sliding distance increases, corrosion products on CuAl14Fe4Mn2Co surface increase at a higher rate compared to CuAl10Ni5Fe4 leading to a decrease in volume loss due to the lubricant effect of copper oxides.
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Abstract

Metallographic investigations and a computer simulation of stresses in a gravity die-casting bushing were performed. Simulation of the casting process, solidification of the thick-walled bushing and calculations of the stress was performed using MAGMA5.3 software. The size variability of phases κIIaffecting the formation of phase stresses σf, depending on the location of the metallographic test area, was identified. The distribution of thermal σtand shrinkage stresses σs, depending on the location of the control point SC in the bushing's volume, was estimated. Probably the nature of these stresses will change slightly even after machining. This can cause variations in operating characteristics (friction coefficient, wear). Due to the strong inhomogeneity of the stress distribution in the bushing's casting, it is necessary to perform further tests of the possibility to conduct thermal treatment guaranteeing homogenization of the internal stresses in the casting, as well as to introduce changes in the bushing's construction and the casting technology. The paper presents the continuation of the results of research aimed at identifying the causes of defects in the thick-walled bushing, die-casting made of CuAl10Fe5Ni5Cr aluminium bronze.
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Abstract

The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn) aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075) was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.
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Abstract

The research described in this contribution is focused on fractographic analysis of the fracture area of newly developed eutectic silumin type AlSi9NiCuMg0.5 (AA 4032), which was developed and patented by a team of staff of the Faculty of Mechanical Engineering. The paper presents determination of the cause of casting cracks in operating conditions. Fractographic analysis of the fracture area, identification of the structure of the casting, identification of structural components on the surface of the fracture surface and chemical analysis of the material in the area of refraction were performed within the experiment. Al-Si alloys with high specific strength, low density, and good castability are widely used in pressure-molded components for the automotive and aerospace industries. The results shown that the inter-media phases Fe-Al and Fe-Si in aluminium alloys lead to breakage across the entire casting section and a crack that crossed the entire cross section, which was confirmed by EDS analysis.
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Abstract

This paper deals with the evaluation of the corrosion resistance of the Al-Si alloys alloyed with the different amount of antimony. Specifically it goes about the alloy AlSi7Mg0,3 which is antimony alloyed in the concentrations 0; 0,001; 0,005; 0,01 a 0,05 wt. % of antimony. The introduction of the paper is dedicated to the theory of the aluminium alloys corrosion resistance, testing and evaluation of the corrosion resistance. The influence of the antimony to the Al-Si alloys properties is described further in the introduction. The experimental part describes the experimental samples which were prepared for the experiment and further they were exposed to the loading in the atmospheric conditions for a period of the 3 months. The experimental samples were evaluated macroscopically and microscopically. The results of the experiment were documented and the conclusions in terms of the antimony impact to the corrosion resistance of the Al-Si alloy were concluded. There was compared the corrosion resistance of the Al-Si alloy antimony alloyed (with the different antimony content) with the results of the Al-Si alloy without the alloying after the corrosion load in the atmospheric conditions in the experiment.
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Abstract

The paper presents research on the effects of soft annealing parameters on a change of the impact strength KC and Brinell hardness (HB) of the EN AC-AlSi11 alloy. The research has been performed according to the trivalent testing plan for two input parameters – temperature in the range between 280°C and 370°C and time in the range between 2 and 8 hours. The application of such heat treatment improves the plasticity of the investigated alloy. The improvement of the impact strength KC by 71% and the decrease of the hardness HB by 20% was achieved for the soft annealing treatment conducted at a temperature 370°C for 8 hours, compared to the alloy without the heat treatment. A change of the form of eutectic silicon precipitations which underwent refinement, coagulation and partial rounding, had a direct effect on the hardness HB and impact strength KC. The results obtained were used to prepare space plots enabling the temperature and time for soft annealing treatment to be selected with reference to the obtained impact strength KC and hardness HB of the alloy with the heat treatment.
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Abstract

The article presents the effect of rotational and travelling speed and down force on the spindle torque acting on the tool in Friction Stir Processing (FSP) process. The response surface methodology (RSM) was applied to find a dependence combining the spindle torque acting on the tool with the rotational speed, travelling speed and the down force. The linear and quadratic models with interaction between parameters were used. A better fitting was achieved for a quadratic model. The studies have shown that the increase in rotational speed causes a decrease in the torque while the increase in travelling speed and down force causes an increase in the torque. The tests were conducted on casting aluminium alloy AlSi9Mg. Metallography examination has revealed that the application of FSP process results in a decrease in the porosity in the modified material and microstructure refining in the stir zone. The segregation of Si and Fe elements was evident in the parent material, while in the friction stir processed area this distribution was significantly uniform.
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Abstract

Presented in this paper are results of an experimental investigation on the rivet flexibility and load transmission in a riveted lap joint representative for the aircraft fuselage. The test specimens consisted of two aluminium alloy Alclad sheets joined with 3 rows of rivets. Two different squeeze forces were applied to install the rivets. Rivet flexibility measurements have been performed under constant amplitude fatigue loading using several methods including two original optical techniques developed by the present authors. The axial tractions in the sheets required to determine the rivet flexibility have been derived from strain gauge measurements. In order to eliminate the effect of secondary bending the strain gauges have been bonded at the same locations on the outside and faying surface of the sheet. The experiments enabled an evaluation of the usefulness of various techniques to determine the rivet flexibility. It was observed that, although the measured flexibility was identical for both end rivet rows, the load transfer through either of these rows was different. Previous experimental results by the present authors suggest that behind the non-symmetrical load transfer distribution through the joint are large differences between the rivet hole expansion in the sheet adjacent to the driven rivet head and the sheet under the manufactured head [1]. It has been concluded that commonly used computation procedures according to which the load transfer is only related to the rivet flexibility may lead to erroneous results.
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Abstract

The use of environmentally friendly inorganic binders and new technologies for cores production is widely discussed topic in recent years. This paper contains information about new hot curing process for core making with alumina-silicate based inorganic binders – geopolymers. Main differences between hot cured geopolymers and hot cured alkali silicate based inorganic binders are discussed. The main objective of this research paper was to investigate basic technological properties of geopolymer binder system such as strength, compaction, storage ability and knock-out properties. For this purpose, three mixtures with different powder additives were prepared and tested in laboratory conditions using specific methods. Strength properties evaluation showed sufficient levels as well as knock-out properties measurement, even with additives B and C originally designed for the use with alkali silicate based two component binder systems. Additives B and C were considered compatible with geopolymer binders after casting production trial results. Storage ability of geopolymers seems to be more sensitive than of alkali silicate based binders in the same tested conditions. Mixtures with geopolymer binder showed 20% more decrease of strength compared to alkali silicate binders after 24 hours in conditions of 25 °C and 65 %RH.
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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

The paper deals with squeeze casting technology. For this research a direct squeeze casting method has been chosen. As an experimental material, the AlSi12 and AlSi7Mg0.3 alloys were used. The influence of process parameters variation (pouring temperature, mold temperature) on mechanical properties and structure will be observed. For the AlSi7Mg0.3 alloy, a pressure of 30 MPa was used and for the AlSi12 alloy 50 MPa. 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 mm, 4 mm, 5 mm, 6.3 mm and 8 mm. The width of each wall was 22 mm and length 100 mm. The mechanical properties (Rm, A5) for individual casting parameters and their individual areas of different thicknesses were evaluated. For the AlSi7Mg0.3 alloy, the percentage increase of the tensile strength was up to 37% and the elongation by 400% (at the 8 mm thickness of the casting). For the AlSi12 alloy, the strength increased from 8 to 20% and the tensile strength increased from 5 to 85%. The minimum thickness of the wall to influence the casting properties by pressure was set to 5 mm (based on the used casting parameters). Due to the effect of the pressure during crystallization, a considerable refinement and uniformity of the casting structure occured, also a reduction in the size of the eutectic silicate-eliminated needles was observed.
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Abstract

Aluminium metal matrix composites (AMMCs) are the fastest developing materials for structural applications. Friction Stir Processing (FSP) has evolved as a promising surface composite fabrication technique mainly because it is an eco-friendly and solid-state process. A spurt in the interest of research community and a resulting huge research output makes it difficult to find relevant information to further the research with objectivity. To facilitate this, the present article addresses the current state of the art and development in surface metal matrix fabrication through FSP with a specific focus on ex-situ routes. The available literature has been carefully read and categorized to present effects of particle size, morphology and elemental composition. The effect of various reinforcements on development of different functional characteristics is also discussed. Effect of main FSP parameters on various responses is presented with objectivity. Based on the studied literature concluding summary is presented in a manner in which the literature becomes useful to the researchers working on this important technology.
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Abstract

Aluminum profiles play an important role in civil engineering (facades, walls with windows) as well as in mechanical engineering (production lines, constructions of 3D printers and plotters). To ensure quick assembly, disassembly or changed the dimensions of constructions it is not possible to use such methods as welding, adhesive or riveting joints. The solution may be to use the so-called “popular lock”. It is a mechanism, the closure of which is caused by tightening of the conical screw, joining the “T” profile in the node. In order to properly design using the presented type of connection, it is necessary to know its strength and stiffness both in simple and complex loads states, also including imperfections. In the literature there is no information about the operation of the construction node with the so-called “popular lock”. The paper presents the results of experimental tests for connections subjected to uniaxial tensile test, paying special attention to the defects that may appear during the assembly. In the next step, a 3D solid connection model was created. Numerical simulations were performed in the Abaqus / Explicite program for both uniaxial tensile test and bending tests in two planes. Limit values of loads above which there is a plastic deformation of the material were determined. Determination of stiffness and strength of a single node allowed to make a simplified connector model. Using the numerical model, the analysis was performed taking into account the influence of imperfections on the work of the entire connection.
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Abstract

Twist extrusion is a processing method involving the extrusion of a sample with a prismatic cross-section using a tool composed of four prismatic parts bisected by a screw component. A beneficial change in mechanical durability is one of the main factors enabling the use of highly durable Al-Mg-Mn-Sc-Zr alloys to construct functional components of non-stationary robots. As part of the present research, ANSYS® software was used to simulate a twist extrusion process. An analysis of a sample entering and passing through the entire twisting area was performed, up to the point of full twisting of the base of the sample. The stress conditions in the sample were analysed as it passed through the twisting area. The highest stress values (reaching up to 600 MPa) were detected at the tips of the sample face as the sample exited the twisting area. The lowest stress values, at around 170 MPa, were detected at the side edges of the sample.
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Abstract

US A356 and US 413 cast aluminium alloys shrinkage characteristic have been discussed in the present study. Specific volume reduction leads to shrinkage in castings and it can be envisaged as a casting defect. Finite difference based casting process simulation software has been used to study the shrinkage characteristic and it is quantified using mathematical formulae. The three dimensional model of the shrinkage defect has been constructed using CAD application software. Shrinkage characteristic has also been quantified through experimental validation studies and compared well with casting process simulation. Shrinkage characteristic study and control is essential for producing defect free castings. Influence of casting shape on the shrinkage characteristic has been studied in this paper.
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Abstract

This study presents an analysis of aluminium cast iron structure (as-cast condition) which are used in high temperatures. While producing casts of aluminium iron, the major influence has been to preserve the structure of the technological process parameters. The addition of V, Ti, Cr to an Fe-C-Al alloy leads to the improvement of functional and mechanical cast qualities. In this study, a method was investigated to eliminate the presence of undesirable Al4C3 phases in an aluminium cast iron structure and thereby improve the production process. V and Ti additions to aluminium cast iron allow the development of FeAl - VC or TiC alloys. In particular, V or Ti contents above 5 wt.% were found to totally eliminate the presence of Al4C3. In addition, preliminary work indicates that the alloy with the FeAl - VC or TiC structure reveals high oxidation resistance. The introduction of 5 wt.% chromium to aluminium cast iron strengthened the Al4C3 precipitate. Thus, the resultant alloy can be considered an intermetallic FeAl matrix strengthened by VC and TiC or modified Al4C3 reinforcements.
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Abstract

Metal alloys with matrix based on an Fe-Al system are generally considered materials for high-temperature applications. Their main advantages are compact crystallographic structure, long-range ordering and structural stability at high temperatures. These materials are based on an intermetallic phase of FeAl or Fe3Al, which is stable in the range from room temperature up to the melting point of 1240°C. Their application at high temperatures is also beneficial because of the low cost of production, very good resistance to oxidation and corrosion, and high mechanical strength. The casting alloy the structure of which includes the FeAl phase is, among others, highaluminium cast iron. This study has been devoted to the determination of the effect of vanadium and titanium on the transformation of the high-aluminium cast iron structure into an in-situ FeAl-VC composite.
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Abstract

The herein paper contains the results of investigations on a new type of cellulose blend used for the manufacture of profiles applied in the process of making gating systems in the foundry industry. A standard cellulose profile was subjected to an experiment. During the experiment the profile was filled with a liquid cast iron and at the same time the temperatures of the liquid metal crystallizing inside the profile were measured as well as the temperature of the outer layer of the profile was controlled. Further, the microstructure of the cast iron, which crystallized out inside the cellulose profile, was analysed and the cellulose, thermally degraded after the experiment, was verified with the use of the chemical analysis method. Moreover, a quality analysis of the original as well as the degraded cellulose profile was run with the use of the FTIR infrared spectroscopy. The presented results revealed that the cellulose blend is aluminium silicate enriched and contains organic binder additives. The cast iron, which crystallized out, tended to have an equilibrium pearlitic structure with the release of graphite and carbides. The generation of disequilibrium ausferrite phases was also observed in the structure.
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Abstract

The study presents the results of the investigations of the effect of Cu, Ni, Cr, V, Mo and W alloy additions on the microstructure and mechanical properties of the AlSi7Mg0.3 alloy. The examinations were performed within a project the aim of which is to elaborate an experimental and industrial technology of producing elements of machines and devices complex in their construction, made of aluminium alloys by the method of precision investment casting. It was demonstrated that a proper combination of alloy additions causes the crystallization of complex intermetallic phases in the silumin, shortens the SDAS and improves the strength properties: Rm, Rp0.2,HB hardness. Elevating these properties reduces At, which, in consequence, lowers the quality index Q of the alloy of the obtained casts. Experimental casts were made in ceramic moulds preliminarily heated to 160 °C, into which the AlSi7Mg0.3 alloy with the additions was cast, followed by its cooling at ambient temperature. With the purpose of increasing the value of the quality index Q, it is recommended that the process of alloy cooling in the ceramic mould be intensified and/or a thermal treatment of the casts be performed (ageing)(T6).
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Abstract

With the increase in wall thickness of the casting of iron-nickel-aluminium-bronze, by the reduction of the cooling rate the size of κII phase precipitates increases. This process, in the case of complex aluminium bronzes with additions of Cr, Mo and W is increased. Crystallization of big κII phase, during slow cooling of the casting, reduces the concentration of additives introduced to the bronze matrix and hardness. Undertaken research to develop technology of thick-walled products (g> 6 mm) of complex aluminium bronzes. Particular attention was paid to the metallurgy of granules. As a result, a large cooling speed of the alloy, and also high-speed solidification casting a light weight of the granules allows: to avoid micro-and macrosegregation, decreasing the particle size, increase the dispersion of phases in multiphase alloys. Depending on the size granules as possible is to provide finished products with a wall thickness greater than 6 mm by infiltration of liquid alloy of granules (composites). Preliminary studies was conducted using drip method granulate of CuAl10Fe5Ni5 bronze melted in a INDUTHERM-VC 500 D Vacuum Pressure Casting Machine. This bronze is a starting alloy for the preparation of the complex aluminium bronzes with additions of Cr, Mo, W and C or Si. Optimizations of granulation process was carried out. As the process control parameters taken a casting temperature t (°C) and the path h (mm) of free-fall of the metal droplets in the surrounding atmosphere before it is intensively cooled in a container of water. The granulate was subjected to a sieve analysis. For the objective function was assume maximize of the product of Um*n, the percentage weight "Um" and the quantity of granules 'n' in the mesh fraction. The maximum value of the ratio obtained for mesh fraction a sieve with a mesh aperture of 6.3 mm. In the intensively cooled granule of bronze was identified microstructure composed of phases: β and fine bainite (α+β'+β'1) and a small quantity of small precipitates κII phase. Get high microhardness bronze at the level of 323±27,9 HV0,1.
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Abstract

The article presents the investigation results of the crystallization (performed by means of the TDA method) and the microstructure of complex aluminium bronzes with the content of 6% Al, 4% Fe and 4% Ni, as well as Si additions in the scope of 1–2% and Cr additions in the scope of 0.1–0.3%, which have not been simultaneously applied before. For the examined bronze, the following tests were performed: hardness HB, impact strength (KU2). For bronze CuAl6Fe4Ni4Si2Cr0.3, characterizing in the highest hardness, wear tests were conducted with dry friction and the dry friction coefficient. The investigations carried out by means of the X-ray phase analysis demonstrated the following phases in the microstructure of this bronze: αCu, γ2 and complex intermetallic phases based on iron silicide type Fe3Si (M3Si M={Fe,Cr,…}). Compared to the normalized aluminium bronzes (μ=0.18–0.23), the examined bronze characterizes in relatively low wear and lower friction coefficient during dry friction (μ=0.147±0.016).
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