Aluminum Alloy Samples Research Articles

Influence of neutron irradiation on Al-6061 alloy produced via ultrasonic additive manufacturing

Samples of aluminum alloy 6061 produced via ultrasonic additive manufacturing (UAM) were irradiated in the High Flux Isotope Reactor (HFIR) up to 17.3 dpa at ~70°C while in contact with water using perforated rabbit capsules. The irradiation campaign included as-received (AR) material, specimens subjected to various post-weld heat treatments (PWHTs, including hot isostatic pressing [HIP]), and reference (wrought) alloy samples. Mechanical tensile tests, accompanied by digital image correlation (DIC) analysis, fractography, and metallography, were performed as a part of the post-irradiation evaluation. The X- and Y-specimens (i.e., oriented in the sonotrode moving and vibration directions, respectively) showed pronounced radiation hardening and ductility decrease. Specific serration flow behavior and propagation of deformation bands were observed under various material conditions up to 3.5 dpa but disappeared at 17.3 dpa. In all cases, the fracture mechanism of X- and Y-specimens was ductile; ductile dimples dominated the fracture surface. Irradiated X- and Y-specimens showed good performance, regardless of material conditions (AR or PWHT). The performance of Z-specimens oriented in the build direction was strongly dependent on the PWHT. The AR and aged specimens showed fracture stress decrease with dose, and they experienced fracture under irradiation after 3.5 dpa; specimen cross section analysis revealed specific interface degradation that was likely related to corrosion. Recrystallization significantly improved in-reactor performance. HIP suppressed interface degradation due to recrystallization and pore removal, which led to good in-reactor performance for Z-specimens.

Прочность клеесварных соединений при длительном воздействии отрицательных температур

The experimental test results of strength of glued and glued-welded joints at room and negative temperatures after long exposure of them at –30 °С and –50 °С are presented. As glue materials, epoxy adhesive, anaerobic adhesive-sealant, silicone sealant and adhesive-melt based on copol-ymer of ethylene with vinyl acetate were used, as substrates, steel and aluminum alloy samples were used. It has been found out that silicone sealant ensures the best strength of glued-welded joints at low temperatures. It was determined that for all the studied types of the glued-welded joints, strength at –30 °С was worse than at –50 °С.

Study on hardness and wear resistance of shot peened AA7075-T6 aluminum alloy

AA7075-T6 aluminum alloy samples were shot peened at various shot peening pressures in the range of 10–70 psi to study their mechanical and tribological properties under dry and mineral oil lubrication conditions. The surface roughness of the shot peened AA7075-T6 samples apparently increased with increased shot peening pressure. The best bearing surface was obtained when the shot peening process was carried out at the highest shot peening pressure of 70 psi. It was found that the increased shot peening pressure increased the hardness and decreased the wear of the shot peened samples. The shot peened samples tested under the mineral oil lubrication condition also had lower wear for higher shot peening pressures due to the combined effects of their higher surface wear resistance and better bearing surfaces. The results clearly showed that using the mineral oil lubricant during sliding apparently decreased the wear of the shot peened samples as a result of the lubricating effect of the lubricant. It could be deduced that the tribological properties of the shot peened AA7075-T6 samples under the dry and lubrication conditions were affected by the shot peening pressure.

Characterization of Precipitation in 7055 Aluminum Alloy by Laser Ultrasonics

After different rolling conditions, four 7055 aluminum alloy samples with different precipitation sizes were measured by scanning electron microscope, transmission electron microscope and laser ultrasonic. The attenuation coefficients of ultrasound measured by laser ultrasonic were calculated in the time domain, frequency domain and wavelet denoising, respectively. The relationship between the precipitate size and attenuation coefficient was established. The results show that the attenuation of the ultrasonic wave is related to the size of the precipitated phase; this provides a new method for rapid non-destructive testing of the precipitation of aluminum alloys.

ВЛИЯНИЕ МАТЕРИАЛА И РАЗМЕРОВ ИЗДЕЛИЯ НА ПАРАМЕТРЫ УПРОЧНЕНИЯ ВОЛНОЙ ДЕФОРМАЦИИ

Previously it was defined that geometrical dimensions of material worked have a significant impact upon the process of wave deformation strengthening, as at equal volumes of strengthened samples and processing modes there are observed different cards of micro-hardness in surface layers. 
 In the paper there are shown investigations of the impact of dimensions of samples made of different material kinds (steel 45, titanium VT 1-0, bronze BRAZh 9-4, aluminum alloy B-95) upon wave deformation strengthening parameters). The investigations mentioned were carried out for the first time on a test desk specially developed. Strengthening effectiveness was estimated according to micro-hardness distribution in a surface layer. The analysis of the results obtained allowed defining that in chosen modes of WDS takes place strengthening not only a face surface but a back one of the sample at that in the core of the sample an initial hardness of material is kept. The investigations carried out allowed defining the fact that at the increase of material thickness from 10 to 20 mm resulted in the growth of degree (ΔHμ) and depth (hμ) of strengthening at WDS of samples of steel 45 - by 24 and 32%, samples of bronze BRAZh 9-4 – by 22 and 21%, samples of titanium VT 1-0 – by 24 and 32%, samples of aluminum alloy B-95 – by 40 and 62%. The samples length increase from 50 to 100 mm is accompanied by the decrease of ΔHμ and hμ at strengthening: steel 45 – by 36 and 70%, bronze BRAZh 9-4 – by 27 and 43%, titanium VT 1-0 – by 24 and 32%, aluminum alloy B-95 – by 40 and 62%.

Influence of Si Content on Fatigue Life for Heat Treated Cast Al-Si-mg Alloy Using Different Quenching Technique

Al-Si-Mg aluminum alloy samples were subjected to solution heat treatment at the temperature of 520 °C for 2 h to attain T42 condition. The heat-treated samples were quenched further in air and water mediums. After quenching, the fatigue life was analyzed with the total strain amplitude (TSA) of 0.4% at the cyclic frequency of 0.3 Hz using a low cycle fatigue testing machine. Air quenched sample has higher life with 1286 cycles than heat-treated and water quenched sample, which were having a fatigue life of 836 cycles and 708 cycles. Tensile mean stress was observed in all samples due to residual stress. Due to fatigue striation, ripple formation was observed in the air quenched sample, and the ripple having the size of 2-3 μm observed under SEM fractography. XRD peaks of Mg2Si and Al3Fe precipitates confirm the proper dispersion during the solution heat treatment.

Study on the Analysis of Main Components of Aluminum Alloy by XRF (X-Ray Fluorescence Analysis) Method

Aluminum alloy has low density, good plasticity, and high strength. It has a large number of applications in many fields. The performance of aluminum alloy is closely related to its alloy composition. The rapid and accurate determination of the content of various elements in aluminum alloy is important for its production and processing. The experiment is based on the energy dispersive X-ray fluorescence analysis method, and analyzes the main elements in the aluminum alloy samples with different composition. The best working mode and the best measurement time of different elements are determined among the partitions. The data measured in the experiment were compared and analyzed by using one-variable, two-variable, and three-variable fitting methods, and the best multiple fitting method for different elements was determined. After ternary fitting, the average absolute errors for Al, Mg, and Si are 0.040%, 0.027%, and 0.007%, respectively, and the average relative errors are 0.040%, 2.111%, and 0.469%, respectively; after binary fitting, the average absolute errors for Cu and Zn are 0.001% and 0.001%, and the average relative errors are 0.061% and 0.070%. The average absolute errors of Zn are 0.001% and 0.001%, and the average relative errors are 0.061% and 0.070%, respectively. The experimental results prove that the XRF method can be applied to the accurate measurement of the main components of aluminum alloy.

Применение метода акустической эмиссии для мониторинга ультразвуковых усталостных испытаний

The ultrasonic fatigue testing (USFT) is an effective method for rapid determination of the fatigue properties of structural materials under high cycle (≥106 cycles) loading. However, the occurrence and accumulation of fatigue damage with this test method remain uncertain due to the limitations of the existing measurement methods. Currently used monitoring methods allow detecting the fatigue cracks, but only in the late stages of failure. Despite the superior sensitivity to localized processes in materials, the use of the acoustic emission (AE) method in ultrasonic testing is extremely difficult due to the presence of resonant noise. This work aimed to suppress resonant noise and extract the signal for early detection of fatigue damage. The authors tested the samples of the AlSi9Cu3 aluminum alloy under the asymmetric cyclic loading (R=0.1) at a resonant frequency of 19.5 kHz with a non-threshold AE registration. The fracture surfaces were analyzed by electron and optical microscopy. The authors processed AE by two different methods: (1) the digital filtering method consisted of detecting resonant noise and removing it from the spectrum; (2) the φ-function method consisted of differentiating the spectrogram by time. The processed spectrograms were integrated by the frequency with further extraction of the AE events using the threshold method. The digital filtering method revealed a correlation between AE signals and fatigue damage, whereas the undamaged control sample showed no signals. The φ-function technique demonstrated ambiguous results, showing high AE activity on the control sample.

Crystallographic structural changes of Al1050 under different types of sheet metal rolling

AA1050 aluminum alloy was studied with symmetric and asymmetric rolling in various technological modes of rolling equipment. The rotational speeds of the rolls and the number of passes varied according to the initially foreseen scheme. Rolling of aluminum sheet alloy was carried out on an experimental - laboratory installation. The crystallographic texture before and after rolling was investigated using X-ray diffraction. X-ray analysis data was processed using MTEX MATLAB toolbox 75. The pole figures and the texture of the samples of aluminum alloy on the Euler space are given. It was shown that pole figures obtained based on X-ray analysis of samples, rolled by the traditional way, had orthorhombic symmetry, and the sample texture had typical components of traditional rolling, like Cu (copper), Su (with lower intensity) B (Brass).

Підвищення властивостей деформованих алюмінієвих сплавів модифікованих нанокомпозиціями

The objective of the work is to obtain a dispersed structure and increase the mechanical and technological properties of deformed aluminum alloys by treating melts with nanodispersed modifiers. The effect of the modification by refractory nanodispersed compositions of titanium carbonitride and silicon carbide on the grain structure and properties of aluminum alloys has been established. Aluminum alloys of the Al-Mg, Al-Mg-Sc system have been studied. The scientific novelty of the work lies in the establishment of the mechanism of influence of the nanodispersed modifier on the grain structure and the set of properties of aluminum alloys. The composition of the modifier is proposed — nanodispersed powders of silicon carbide (SiC) and titanium carbonitride (TiCN) with fractions of 50 ... 100 nm. The microstructure of alloys was studied under optical microscopes. The strength properties of the alloys were determined on a TIRAtest300 machine. Fluidity was determined using the spiral test method. In the modified samples of aluminum alloys, improved technological properties were achieved. It was found that, in alloys AMg5 and 1545, the fluidity increased by an average of 10 %. After the modification, we obtained a homogeneous dispersed structure of aluminum alloys. It turned out that the average grain size in the modified samples of alloy 1545 decreased 1.6 times in comparison with the initial state due to the increase of strength characteristics by 14… 20 %. A series of experimental-industrial melting of AMg5 and 1545 alloys has been carried out. The effective influence of a refractory modifier based on silicon carbide and titanium carbonitride on the properties of aluminum alloys has been proved. The results of the work are of practical importance for aviation and space technology products.

LOADS ACTING ON A RIGID WALL UPON IMPACT OF A HIGH POROUS CYLINDER

This paper describes a load on a structure at the instance of its impact with an aircraft from the side of onboard equipment. The correctness and applicability of the model of the aircraft presented in the form of a rigid-plastic rod (the Riera approach) is estimated when studying the effect of onboard equipment. This impact is simulated using bulk perforated samples of aluminum alloy. Calculations are carried out using the proposed model in one-dimensional approximation along with direct three-dimensional modeling of the impact by the finite element method using the LS-DYNA package. Both of these approaches allow one to investigate the process of loading a rigid wall. The quantitative and qualitative differences between these approaches and the Riera approach are shown.

PRECIPITATE EXTRACTION FROM 3003 ALUMINUM ALLOY PRODUCED BY TWIN ROLL CASTING/ EXTRAÇÃO PRECIPITADA DE 3003 LIGAS DE ALUMÍNIO PRODUZIDAS POR FUNDIÇÃO EM ROLO DUPLO

In the present study four different precipitate extraction techniques were investigated on a 3003 aluminium alloy samples (twin-roll cast and homogenized conditions). The dissolution product was analyzed with the help of X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The performance of four chemical solutions (iodine solution, perchloric acid, oxine solution, and phenol solution) was compared, and the phenol solution presented the best precipitate extraction results. The phases in the cast and homogenized microstructures were identified, explaining some aspects of the phase transformation during the homogenization.

Fatigue tests simulation of materials with a random endurance limit

Fatigue tests of materials are characterized by long duration and high cost. In this regard, it is relevant to develop methods for modeling test results in the widest possible range of loads. Fatigue curve mathematical model includes the equation of the relationship between the amplitude of the stress and the durability of the samples, considering the random nature of the values of durability and the limit of unbounded endurance. At the first stage, the values of the model parameters are determined using the maximum likelihood function using real test data in a limited range of stress amplitudes. At the second stage, the problem solution is found considering the random value of the limit of unbounded endurance. Moreover, the mean estimate is obtained from the solution of the first part of the problem. The estimate of the unbounded endurance limit variance is obtained by calculation from the variance balance conditions. The results of modeling fatigue tests for aluminum alloy samples in a wide range of stress amplitude values are presented. Simulation results for determining the values of the fatigue curve left tolerance are considered.

Oxime-modified aluminum (III) isopropoxide: A promising sol-gel precursor coating to improve mechanical strength of an aluminum alloy

This research is concerned with the investigation of the capability of alumina coatings, deposited by dip coating methods to improve mechanical properties of aluminum alloys and anodized aluminum alloy. Alumina coatings were deposited using oxime-modified aluminum (III) isopropoxide as a sol–gel precursor. The Scanning electron microscopy (SEM) images of the coated samples suggest deposition of uniform and crack free alumina coatings. The mechanical property of the bare, dip coated, anodized and coated anodized aluminum alloy samples were investigated by the slow strain rate test. It indicates that simply dip coated surface have higher ultimate tensile strength as compare to other samples.

Further insights on the stress equilibrium method to investigate macroscopic residual stress fields: Case of aluminum alloys cylinders

The stress equilibrium, SE, method has been shown to be a very powerful, reliable tool for calculating the un-stressed lattice parameter, a0, as a critical requirement for the determination of the residual stress, RS, by diffraction techniques. The method can be used in cases where others, such as the powder or comb ones, are limited (e.g., in age-hardenable aluminum alloys components, where a0 can be affected). Owing to its potential, this method can address complex cases that, however, have not yet been sufficiently exploited. In particular, it makes it possible to delve into the effect of microstructural factors (e.g., texture variations) on the macroscopic residual stress, M-RS. Here, the M-RS obtained after quenching and slow cooling of cylindrical samples of aluminum alloys has been investigated. Data obtained from neutron and synchrotron radiation diffraction in AA5083 and AA2014 alloy samples (of different size), respectively, have been used. Specifically, the development of a texture gradient, a very common consequence derived from conventional manufacturing processes of components, has been taken into account. The known fact that a parabolic profile of the M-RS is obtained in cylindrical samples is used to generalize the SE method to determine a0 and to strengthen its quality and reliability.

Copper enrichment on aluminium surfaces after electropolishing and its effect on electron imaging and diffraction

Electropolishing is the most common method of preparing samples of aluminium alloys for scanning and transmission electron microscopy, as it yields a good surface quality and large flat, electron-transparent areas. Like many chemical surface treatment procedures, the electropolishing process can create a Cu-rich layer between the aluminium matrix and the outermost aluminium oxide layer. The Cu layer is shown to be crystalline, which causes several distinct effects on electron images and diffraction patterns, that can easily be misinterpreted as originating from features inside the aluminium matrix. The layer is a modified θ’–Al2Cu phase, with a semi-coherent interface with aluminium. A θ’ superstructure suggested in this paper can explain lattice modulations with a 1 nm spacing that have been observed in the [011]Al zone axis of electropolished specimens. Evidence of Cu diffusion into the Al matrix was also found. The surface enrichment can also occur in Cu-free aluminium alloys, as small amounts of Cu can be introduced from outside sources through the electrolyte solution.

Comparison of physical and virtual simulation of multi-axial forging processes on EN-AW 6082 aluminium alloy

The multiaxial deformation of EN-AW 6082 Aluminium alloy samples was performed by a Gleeble 3800 thermo-physical simulator equipped with MaxStrain system. The samples were cyclic forged so, that the accumulated equivalent plastic strain increased by the nearly same at every step. The increment of plastic strain was about 0.4, while the maximal equivalent strain was around 4. Between forging steps, pictures were made about the deformation zone of the samples to track the geometric deformation. The simulator was programmed to implement different strain rates at ambient temperature. The tested strain rate was 0.1 1/s. The unforeseeable temperature increase due to the plastic deformation was measured by thermoelements connected next to the deformation zone.The finite element model of the physical simulations was created in QForm3D 9.0.9. software. During the physical simulation, tool movements and temperature were recorded. These movements were used in the virtual simulation to control the process. The Temperature-Time and Force-Displacement curves of the simulations were compared to evaluate the finite element model.

Superhydrophobic Films with Enhanced Corrosion Resistance and Self-Cleaning Performance on an Al Alloy.

In this article, a novel and facile method is used to construct superhydrophobic surfaces on aluminum alloys. A solution of aluminum chloride hexahydrate and N-dodecyltrimethoxysilane (DTMS) in ethanol was used as the electrolyte solution. The hydrolysis of DTMS was accelerated during the electrodeposition process, and the hydrolysate was bonded to a pretreated aluminum surface. The prepared aluminum alloy sample exhibits both superhydrophobicity (the surface water contact angle reached 155°) and excellent corrosion resistance. The inhibition efficiency of this sample is as high as 99.9% in 3.5 wt % NaCl solution, which remains at 98% even after 30 days of immersion. Thus, our fabrication can be well applied to the field of marine corrosion protection. Therefore, the working mechanism was discussed by confocal Raman microspectroscopy (CRM). In addition, the investigation by CRM and electrochemical impedance spectroscopy (EIS) also indicates that superhydrophobic samples show good stability in NaCl solution. The fabrication method can inspire new ideas for the construction of superhydrophobic aluminum alloys in the marine environment.

Inelastic behavior and destruction of materials under isothermal and non-isothermal, simple and complex loads

The paper deals with mathematical modeling of inelastic behavior and destruction of structural materials (steels and alloys) under simple, complex, isothermal and non-isothermal loads in repeated and long-term exposures to thermomechanical loads. The modeling is carried out on the basis of the applied theory of inelasticity, which belongs to the class of flow theories in combined hardening. The main provisions are formulated and a summary of the main equations of the applied theory of inelasticity is given. The material functions closing the applied theory of inelasticity are determined, and the connection of the defining functions with the material ones is given. Further, the results of some original experimental studies are considered, which are compared with the results of calculations based on the applied theory of inelasticity. In all studies, inelastic deformation is performed under conditions repeated and long-term exposures to thermomechanical loads. Inelastic deformation of AL-25 aluminum alloy samples under uniaxial tension-compression under both isothermal and non-isothermal cyclic loading is considered. Inelastic deformation under complex loading along the two-link polyline deformation paths with different deformation rates under high temperature conditions is studied on tubular 30HGSA alloy samples. Inelastic deformation of tubular stainless steel 304 samples under complex loading at elevated temperatures is considered. Soft cyclic loading is performed along two-link stress trajectories with different fracture angles. At the end of the links of the stress trajectory, exposure is carried out for 8 hours. The results of the calculations based on various theories used in the calculations are analyzed. Inelastic deformation and destruction of samples made of 12X18N9 stainless steel under rigid cyclic deformation under both isothermal and non-isothermal loads is considered. The duration of the loading cycle is 4 minutes, which allowed the effects of healing and embrittlement to appear at a high temperature. There is a significant difference (much higher) in the number of cycles to failure in common-phase and anti-phase modes of changes in force strain and temperature.

Investigation of Selected Polymer Composite-Aluminum Oxide Coating Tribological Systems

The tribotesting of friction systems requires discussion on proper selection of its conditions and data presentation. System tribology is based, for example, on analysis of the friction contact, the roughness of the cooperating surfaces, and the wear rate of the rubbing elements or coefficient of friction in relation to the sliding distance. Friction pairs, consisting of an aluminum alloy sample with an oxide layer (Al2O3) with and without the addition of inorganic fullerenes like tungsten disulphide (IF-WS2) nanoparticles on its surface cooperating with a counter-sample made of polymer composites prepared on the basis of phenol-formaldehyde resin with different fillers, were tested using a device with a pin-on-plate friction pair system. The results of the experiments showed sufficient durability of the Al2O3 and Al2O3/IF-WS2 oxide coatings in combination with the polymer composite. It was found that resin fillers such as cotton fibers, jute fibers, molybdenum disulphide (MoS2) or graphite (C) influence the friction behavior of the tribological pairs. Although the values of the coefficient of friction obtained in the tests were quite high, their course during the tests ensured stable cooperation of the aluminum coating/polymer composite friction pair on a 15 km distance, under a load of 0.5 MPa. The lowest coefficients of friction were obtained for oxide layers formed on aluminum combined with a polymer composite filled with cotton fibers and graphite. These studies provide information on the tribological properties of commercially available polymer composites cooperating with the produced oxide coatings, supplementing the available literature with the results of research on new, so far unexplored tribological partners. Microscopic investigation of the structure and morphology of the formed surface oxide layers and also microgeometry studies of both the friction elements were used to better understand the obtained research results.