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EN
This paper investigates the stress and strain state as well as formation processes of structure and features of aluminum alloys during the hot extrusion. It has been shown that during the hot extrusion the ring layers of an extruded element experience not only longitudinal and transverse deformations, but also a slip. The slip increases from inner layers to the surface layer. The tensile principal stresses and the sum of slip deformations also increase. It has been also demonstrated that at the exit of the pressing part the tensile principal stresses have different directions, forming an angle with extruder axis, which also increases towards the surface. In conclusion, it has been stated that the main radial and circumferential deformations act as restraining deformations.
EN
The paper presents selected results of numerical analysis and experimental verification. The subject is the analysis of cold forging of a thin-walled hollow ball. The process of making a ball out of aluminum alloy and steel is considered. A distinctive feature of this process is the use of a special deformable insert assembly. It consists of two shaped expanding tubes, a distance ring and a centering tube. Each of these elements has a specific function, which is characterized in this article. FEA simulation allowed proving the functionality of the insert assembly and comparing the cold forging of a steel and aluminum part, using the same inserts. Attention was also focused on the impact of the accuracy of the positioning of the insert assembly. Experimental verification confirmed the correctness of the modeling and complemented the results from FEA analysis
EN
The aim of the work was to analyze the method of preparing the aluminum surface in terms of the functional properties of glued joints with the use of one-component polyurethane adhesive. Six methods of surface treatment of EN AW-5251 aluminum alloy were tested. In addition, changes in the shear strength of adhesive joints after environmental exposure were determined. The best surface preparation processes were atmospheric plasma and anodizing.
PL
Celem pracy była analiza sposobu przygotowania powierzchni aluminium pod kątem właściwości użytkowych połączeń klejonych z zastosowaniem jednoskładnikowego kleju poliuretanowego. Zbadano sześć metod obróbki powierzchni stopu aluminium EN AW-5251. Ponadto określono zmiany wytrzymałości połączeń klejonych na ścinanie po ekspozycji środowiskowej. Najlepszym sposobem przygotowania powierzchni była plazma atmosferyczna i anodowanie.
EN
This paper presents the results of flow forming tests for the 6060 aluminum alloy in the T5 heat treatment condition. The tests were conducted on a cylindrical mandrel using two forming rollers without the use of a cooling agent. The purpose of the study was to conduct two experiments. In both experiments, the final gap between the roller and the mandrel was designed to be the same. The impact of the deformation value on the change in the mechanical properties of the material with the simultaneous impact of the number of forming passes was determined. In addition, the effect of the elimination of a coolant on the process was analyzed. The material temperature rise caused by friction between a pair of working parts: the roller—and the workpiece—were examined with a thermal imaging camera. This paper presents the results of microhardness tests and analyzes the impact of the forming parameters on the strength properties of the alloy. Because the forming process was done without cooling, the impact of the temperature prevailing during the deformation process on the change in the strength of the alloy was studied and analyzed. The deformation zone in which intensive grain deformation took place was determined.
EN
The paper presents the results from a study on the possibility to use citric acid as an ecological inhibitor of corrosion in aluminum alloy EN AW-2024 in 0.5 М solution of H2SO4. The study has been carried out by using electrochemical techniques, such as open circuit potential and chronoamperometry. The results reveal that the presence of citric acid in the studied acid medium reduces the corrosion degree of the EN AW-2024 aluminum alloy. The inhibition efficiency increases together with increasing the concentration of the citric acid. The study shows that the citric acid can be used as an ecological inhibitor to fight corrosion in a solution of H2SO4.
EN
This work is focused on the modelling of experimental behaviour of a bone-shape sample made of aluminium alloy AW5083 under tension. This behaviour involves propagating instabilities, namely Lueders bands and the Portevin–Le Chatelier effect. A series of experiments was performed at room temperature for three loading rates, showing the instabilities and failure. In the paper a large strain thermovisco-plasticity model is proposed and used for finite element simulations. This model contains initial softening and a hardening function based on the Estrin–McCormick concept to represent serrations and travelling shear bands. The issues of instability sources and regularisation are considered. The predictive capabilities of the model are examined. The proposed models are able to reproduce both Lueders bands and the PLC effect. Simulation results show good agreement with experiments regarding force–displacement diagrams and temperature levels.
EN
This article presents the influence of the brushing process on residual stress and surface roughness of EN AW-2024-T3 aluminum alloy joints welded using the Friction Stir Welding (FSW) method. Butt joints with thicknesses of 2 mm were brushing with using ceramic brush. The aim of the study was to find optimal parameters of the brushing process, which would significantly improve the functional properties of welded joints. The experiments were carried out in two steps. In the first stage of the research, the feed rate was changed in the range f = 40 ÷ 120 mm / min with a constant brushing depth d = 0.5 mm. The roughness decreased from Sa = 5.285 µm for the specimen after welding to Sa = 2.460 µm for the f = 120 mm/min and d = 0.5 mm. The change in the parameters of the brushing process did not have a significant impact on the state of residual stresses. Hence, in the second step, the brushing depth was increased in steps of 0.1 mm. The best properties were obtained for f = 120 mm / min and d = 0.6 mm (variant 6A), where roughness was Sa = 0.443 µm and compressive stresses σ = -118 MPa.
EN
This study deals with the selection of optimum parameters for friction stir processing of Al alloy 6061-T6 reinforced with a hybrid nanoparticle (B4C and SiO2) in terms of their effect on the mechanical properties (hardness, tensile strength, and wear resistance) using Taguchi method. This work was carried out under four parameters each one running in three levels; rotational speeds (800, 1000 and 1200) rpm, travel speeds (10, 20, and 30) mm/min, holes depth (2, 2.5, and 3) mm, and mixing ratio of (SiO2/B4C) nanoparticles (1/1, 1/2, and 1/3), using L9 (34) Taguchi orthogonal array. Tensile strength and microhardness tests were conducted to evaluate the mechanical properties, in addition to the wear resistance test which is carried out using a pin-on-disk device. The microstructure was examined by optical microscopy, field emission scanning electron microscopy, and x-ray diffraction analysis. It was found that the highest tensile strength (223) MPa at 1200 rpm rotational speed, 30 mm/min traverse speed, 2.5 mm holes depth, and 1/2 (SiO2/B4C) nanoparticles mixing ratio, the highest hardness reached is (155) HV, then decreases in the direction of thermomechanically affected zone (TMAZ), heat affected zone (HAZ), and the base material at (1200) rpm rotational speed, (30) mm/min linear speed, a hole depth of (2) mm and (1/3) mixing ratio of (B4C/SiO2) nanoparticles. The wear behavior was of a mild type or an oxidative type at low loads (5 N), which became severe or metallic wear at higher loads (20 N) at fixed sliding time and speed. The (ANOVA) table has been used to determine which parameter is the most significant using MINITAB software.
EN
Thin-walled aluminum alloy tubes used for structural applications can be produced by various processes among which friction stir welding process (FSW) has emerged rapidly due to its superior welded properties. But, FSW of tubular components is complex due to its curvature which makes it challenging to get the desired quality of the tube. Hence, in the present study, an attempt was made to fabricate longitudinal FSWed tubes of AA5083-O alloy. A novel parameter window highlighting their effects on the weld quality was presented, and the significant process parameters were optimized to get a defect-free good-quality welded tube. In this regard, X-ray micro-computed tomography, hardness and uniaxial tensile tests of the weld zone (WZ) were carried out to assess the weld quality. Negligible amount of porosity was observed in the WZ, and the hardness was comparable to that of the base material. The joint efficiency obtained was 87%, suggesting homogeneity of the WZ. To get further insight into the WZ homogeneity, the failure mechanism along with the microscopic damage initiation characteristic of the tensile samples was studied. Failure of these samples took place in between the nugget zone and the thermo-mechanically affected zone, and a mixed type of fracture was observed. Three types of void nucleation mechanisms viz., inclusion or particle cracking, interface debonding, and matrix cracking coexisted in the welded sample among which particle cracking was the most significant. Also, the surface roughness of the WZ was measured and it was observed that the material flow during the welding process affected the average roughness value.
10
EN
A novel dieless clinching process free of blank holder was proposed in this study. This novel clinching process applied to joining Al5052 sheets under the forming forces from 24 to 54 kN was investigated experimentally. The joint geometrical characteristics, static mechanical strength, energy absorption and failure modes were revealed. From the results, the sound joints can be produced under various forming forces from 24 to 54 kN. With the forming force increasing, the neck thickness was increased continually while the interlock value remained almost constant. On the other hand, the protrusion height of clinched joint was reduced continually with the forming force increasing. Both the tensile strength and shear strength were enhanced with the forming force increasing. Under the forming force of 54 kN, the tensile strength and the shear strength were 1249 and 1107 kN, respectively. In general, a larger joining force leads to a better clinched joint with lower protrusion height and higher mechanical strength.
11
PL
Celem pracy była ocena wpływu sezonowania naturalnego na nośność połączeń klejowych czopowych walcowych poddanych i niepoddanych dodatkowej obróbce cieplnej (dotwardzaniu cieplnemu). Złącza klejowe wykonano ze stopu aluminium EN AC-AlSi7Mg0,3 (tuleja) oraz kompozytu szklano-epoksydowego (czop). Elementy połączono ze sobą za pomocą kompozycji klejowej Araldite 2014. Połączenia klejowe poddano próbie ścinania osiowego. Badania przeprowadzono dla kilku wariantów sezonowania: sezonowania przez 6 miesięcy w okresie letnim, sezonowania przez 6 miesięcy w okresie zimowym, sezonowania przez jeden rok oraz przez dwa lata. Wyniki badań wskazują, że sezonowanie próbek niepoddanych dodatkowej obróbce cieplnej spowodowało zwiększenie nośności połączeń klejowych o 0,1-21,3%. Natomiast w przypadku próbek poddanych dodatkowej obróbce cieplnej sezonowanie przyczyniło się do zmniejszenia nośności złączy o 0,6-24%. Analiza istotnych różnic (test t-Studenta) wykazała, że w przyjętym zakresie zmienności czynników wejściowych warunki sezonowania nie miały istotnego wpływu na nośność połączeń klejowych. Jedynie nośność próbek z dodatkową obróbką cieplną sezonowanych przez okres 2 lat wykazuje istotne statystycznie różnice w porównaniu do pozostałych wariantów (pv=0,23%). Wyniki analizy korelacji i regresji wskazują, że w przypadku próbek poddanych dodatkowej obróbce cieplnej nośność połączeń klejowych maleje wraz ze wzrostem czasu sezonowania (r=-0,835). W przypadku próbek, które nie zostały poddane dodatkowej obróbce cieplnej, nośność złączy zwiększa się wraz ze wzrostem czasu sezonowania (r=0,841).
EN
The aim of the work was to investigate the influence of natural seasoning on the load capacity of cylindrical adhesive joints subjected to and not subjected to additional heat treatment. The adhesive joints ware made of ENAC-AlSi7Mg0.3 aluminum alloy (sleeve) and glass-epoxy composite (pivot). The elements were joined together using the Araldite 2014 adhesive composition. The adhesive joins were subjected to an axial shear test. The research was carried out for several variants of seasoning: seasoning for 6 months in the summer period, seasoning for 6 months in the winter period, seasoning for one year and two years. The test results show that the seasoning of samples not subjected to additional heat treatment increased the load capacity of the adhesive joints by 0.1-21.3%. On the other hand, in the case of samples subjected to additional heat treatment, seasoning contributed to the reduction of the load capacity of the joints by 0.6-24%. The analysis of significant differences (Student's t-test) showed that in the adopted range of variability of the input factors, the seasoning conditions did not have a significant impact on the load capacity of the adhesive connections. Only in the case of samples with additional heat treatment, seasoned for 2 years, the load capacity shows statistically significant differences compared to other variants (pv=0.23%). The results of correlation and regression analysis indicate that in the case of samples subjected to additional heat treatment, the load capacity of the adhesive joints decreases with the increasing duration of seasoning (r=-0.835). In the case of samples that have not been subjected to additional heat treatment, the load capacity of the joints increases with the increasing duration of seasoning (r=0.841).
12
EN
The subject of this text is the description of structural materials used in the structure of railway vehicle wheels. The characteristic of this structural element as well as its functional and material requirements are presented. The description of commonly used carbon steels and alternative construction materials, such as cast steel, ADI cast iron or aluminum alloys, are presented in the further part, which are supposed to limit the wear of the wheel-rail friction pair and reduce the level of noise.
PL
Przedmiotem niniejszego tekstu jest opis materiałów konstrukcyjnych stosowanych w budowie kół pojazdów szynowych. Przedstawiono charakterystykę tego elementu konstrukcyjnego, a także jego wymagania funkcjonalne oraz materiałowe. W dalszej części zaprezentowano opis powszechnie używanych stali węglowych oraz alternatywnych materiałów konstrukcyjnych, takich jak staliwa, żeliwa ADI czy stopy aluminium, które w założeniu miałyby ograniczać zużywanie pary ciernej koło-szyna oraz zmniejszać poziom emitowanego hałasu.
EN
As the second largest machinery industry, the energy-intensive cable industry not only creates a lot of economic value but also consumes a lot of energy. It is an inevitable requirement to promote the technological development of the industry in the new era to improve the quality and efficiency and realise industrial energy-saving and consumption reduction. In order to obtain good strength and conductivity, the metal rods of cable are usually heat-treated for several hours or even several days after the rods are extruded, this is a major energy consuming process in traditional production. Based on the background, this study adopted the energy-saving equal-channel angular pressing (ECAP) technology to replace the traditional heating treatment process, and converted the simple heat conduction with thermo-mechanical energy transfer, so as to realise the good strength and conductivity matching of the cable aluminum alloy material. In this study, energy-saving ECAP technology is used to replace the traditional heat treatment process, and heat-mechanical energy transfer is used to replace the simple heat conduction, so as to achieve good strength and conductivity matching of cable aluminium alloy material. The results show that the suitable ECAP process routes can improve the microstructure of aluminum alloy with higher strength and conductivity than the traditional heating process. The research results can be used for technology upgrading and low carbon production in cable industry due to the significantly time reduction of the energy-consuming heat treatment and the high-efficient obtainment of high-quality production.
EN
Activated tungsten inert gas (ATIG) welding has a good depth of penetration (DOP) as compared to the conventional tungsten inert gas (TIG) welding. This paper is mainly focused on ATIG characterization and mechanical behavior of aluminum alloy (AA) 6063-T6 using SiO2 flux. The characterization of the base material (BM), fusion zone (FZ), heat affected zone (HAZ) and, partially melted zone is carried out using the suitable characterization methods. The weld quality is characterized using ultrasonic-assisted non-destructive evaluation. A-scan result confirms that the ATIG welded samples have more DOP and less bead width as compared to conventional TIG. The recorded tensile strength of ATIG with SiO2 is better than the conventional TIG welding. The failure mode is ductile for ATIG welding with larger fracture edges and is brittle in the case of conventional TIG welding.
EN
In this paper, as a purpose to apply the supersaturated solid-solutionized Al-9Mg alloy to the structural sheet parts of automotive, tensile tests were conducted under the various conditions and a constitutive equation was derived from the tensile test results. Al-9Mg alloy was produced using a special Mg master alloy containing Al2Ca during the casting process and extruded into the sheet. In order to study the deformation behavior of Al-9Mg alloy in warm temperature forming environments, tensile tests were conducted under the temperature of 373 K-573 K and the strain rate of 0.001/s~0.1/s. in addition, by using the raw data obtained from tensile tests, a constitutive equation of the Al-9Mg alloy was derived for predicting the optimized condition of the hot stamping process. Al-9Mg alloy showed uncommon deformation behavior at the 373 K and 473 K temperature conditions. The calculated curves from the constitutive equation well-matched with the measured curves from the experiments particularly under the low temperature and high strain rate conditions.
EN
Refill friction stir spot welding (refill FSSW) was used to weld 3.2-mm-thick 2060 aluminum alloy. Joint formation, defect characteristics and tensile-shear property were analyzed. Results show that keyhole can be completely eliminated under different plunge depths. However, defects such as void, unconnected welding, hook can be observed under the plunge depths of 3.4-4 mm.The size of the overall void initially increased and then decreased with the increase of the plunge depth, while the void was the smallest under the plunge depth of 3.4 mm. The unconnected defect at the lap interface gradually shrank a welding line from obvious crack. Different hook morphologies were observed under different plunge depths. The tensile-shear load of joint increased with the increase of the plunge depth and was up to the largest under the plunge depth of 4 mm. All the tensile-shear specimens fractured along the lap interface. Compared with the void, the unconnected defect had a greater influence on the tensile-shear property.
EN
The four-layer stack accumulative roll bonding (ARB) process using AA1050, AA5052 and AA6061 alloy sheets is performed up to 2 cycles without a lubricant at room temperature. The sample fabricated by the ARB is a multi-layer complex aluminum alloy sheet in which the AA1050, AA5052 and AA6061 alloys are alternately stacked to each other. The changes of microstructure and mechanical properties with annealing for the-ARBed aluminum sheet are investigated in detail. The as-ARBed sheet shows an ultrafine grained structure, however the grain diameter is some different depending on the kind of aluminum alloys. The complex aluminum alloy still shows ultrafine structure up to annealing temperature of 250℃, but above 275℃ it exhibits a heterogeneous structure containing both the ultrafine grains and the coarse grains due to an occurrence of discontinuous recrystallization. This change in microstructure with annealing also has an effect on the change of the mechanical properties of the sample. Especially, the specimen annealed at 300℃ represents abnormal values for the strength coefficient K and work hardening exponent n value.
EN
The influence of the cooling rate on the extent of precipitation hardening of cast aluminum alloy (ADC12) was investigated experimentally. This study explored the cooling rate of the solidification of Cu in the α-Al phase to improve the mechanical properties of ADC12 after an aging process (Cu based precipitation hardening). The solid solution of Cu occurred in the α-Al phases during the casting process at cooling rates exceeding 0.03°C/s. This process was replaced with a solid solution process of T6 treatments. The extent of the solid solution varied depending on the cooling rate; with a higher cooling rate, a more extensive solid solution was formed. For the cast ADC12 alloy made at a high cooling rate, high precipitation hardening occurred after low-temperature heating (at 175°C for 20 h), which improved the mechanical properties of the cast Al alloys. However, the low-temperature heating at the higher temperature for a longer time decreased the hardness due to over aging.
EN
Aluminum alloys, due to appropriate strength to weight ratio, are widely used in various industries, including automotive engines. This type of structures, due to high-temperature operations, are affected by the creep phenomenon; thus, the limited lifetime is expected for them. Therefore, in designing these types of parts, it is necessary to have sufficient information about the creep behavior and the material strength. One way to improve the properties is to add nanoparticles and fabricate a metal-based nano-composite. In the present research, failure mechanisms and creep properties of piston aluminum alloys were experimentally studied. In experiments, working conditions of combustion engine pistons were simulated. The material was composed of the aluminum matrix, which was reinforced by silicon oxide nanoparticles. The stir-casting method was used to produce the nano-composite by aluminum alloys and 1 wt.% of nanoparticles. The extraordinary model included the relationships between the stress and the temperature on the strain rate and the creep lifetime, as well as various theories such as the regression model. For this purpose, the creep test was performed on the standard sample at different stress levels and a specific temperature of 275 oC. By plotting strain-time and strain rate-time curves, it was found that the creep lifetime decreased by increasing stress levels from 75 MPa to 125 MPa. Moreover, by comparing the creep test results of nanoparticle-reinforced alloys and nanoparticle-free alloys, 40% fall was observed in the reinforced material lifetime under 75 MPa. An increase in the strain rate was also seen under the mentioned stress. It is noteworthy that under 125 MPa, the creep lifetime and the strain rate of the reinforced alloy increased and decreased, respectively, compared to the piston alloy. Finally, by analyzing output data by the Minitab software, the sensitivity of the results to input parameters was investigated.
EN
Computational Materials Engineering (CME) is a high technological approach used to design and develop new materials including the physical, thermal and mechanical properties by combining materials models at multiple techniques. With the recent advances in technology, the importance of microstructural design in CME environments and the contribution that such an approach can make in the estimation of material properties in simulations are frequently discussed in scientific, academic, and industrial platforms. Determination of the raw material characteristics that can be modeled in a virtual environment at an atomic scale by means of simulation programs plays a big role in combining experimental and virtual worlds and creating digital twins of the production chain and the products. In this study, a new generation, alternative and effective approach that could be used to the development of Al-Si based wheel casting alloys is proposed. This approach is based on the procedure of optimizing the physical and thermodynamic alloy properties developed in a computer environment with the CME technique before the casting phase. This article demonstrates the applicability of this approach in alloy development studies to produce Al-Si alloy wheels using the low pressure die casting (LPDC) method. With this study, an alternative and economical way is presented to the alloy development studies by trial and error in the aluminum casting industry. In other respects, since the study is directly related to the automotive industry, the reduction in fuel consumption in vehicles is an expected effect, as the new alloy aims to reduce the weight of the wheels. In addition to conserving energy, reducing carbon emissions also highlights the environmental aspects of this study.
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