Microstructure Of Aluminum Alloy Research Articles

Effect of quenching on post-processed aluminum 6082 alloy using friction stir processing

Recently, experimentation on cooling media alteration during Friction Stir Processing (FSP) had put impetus efforts to analyzing the effects on microstructures of Aluminum alloys. On the other hand, developing alternative cooling processes like the artificial aging of post-processed FSPed components is also seized the consideration to study the grain refinement of Al-Alloys. This work focuses on studying the effects of oil quenching on FSPed Al 6082 alloy after completing the conventional procedure. Unconventional to the air cooling and water cooling during the machining process, the post-processed Al 6082 alloy (PPA) was submerged for two hours in an oil bath, and effects on microstructure, microhardness, and tensile strength were compared with conventional cooling media. The increments that occurred in microhardness and tensile strength revealed that the PPA had gained mechanical strength after oil quenching. Subsequently, PPA’s microstructure became coarser unlike the conventional characteristic of the FSPed specimen.

Microstructure, strength and welding window of aluminum alloy−stainless steel explosive cladding with different interlayers

Aluminum 5052 (Al 5052)−stainless steel 316 (SS 316) plates were explosively cladded with Al 1100, pure copper and SS 304 interlayers. The operational parameters viz., standoff distance, explosive mass ratio (mass ratio of the explosive to the flyer plate) and inclination angle were varied and the results were presented. The advent of interlayer relocates the lower boundary of the welding window, and enhances the welding regime by 40%. A triaxial welding window, considering the influence of the third operational parameter, was developed as well. Use of interlayer transforms the continuous molten layer formed in the traditional Al 5052−SS 316 explosive clad interfaces into a smooth interface devoid or with a slender presence of intermetallic compounds. The microhardness, ram tensile and shear strengths of the interlayered clads are higher than those of the traditional explosive clads, and the maximum values are witnessed for stainless steel interlaced Al 5052−SS 316 explosive clads.

Investigation of the microstructure and mechanical properties of AA6063 and AA7075 dissimilar aluminium alloys by friction stir welding process

Friction stir welding (FSW) is one of the advanced welding processes to join both similar and dissimilar alloys and materials. The FSW process is most widely used in automotive, aerospace, and nautical industries to join similar and dissimilar aluminum alloys. In this research work, two dissimilar aluminum alloys of AA6063 and AA7075 were joined using the friction stir welding process and characteristics of the welded joint were studied. Friction stir welded joints of dissimilar alloys were studied by varying the input process parameters of tool rotating speed of 800, 1000 to 1200 rpm with varied the welding speed of 30 to 60 mm/min. The influence of varying the input parameters was studied by the mechanical properties of the friction stir welded (FSW) specimen and the microstructure were analyzed using SEM images.

Corrosion Properties for Roll-Bonded Two-Layer AA4045/AA3003 for Heat Exchanger Application

During their service life, heat-exchangers are subjected to a variety of environments, including heating and cooling cycles, salt water environment on the surface, and mechanical loading. As a result, corrosion performance is critical, as perforation of the material could result in system failure. Corrosion behaviour of brazed roll-bonded aluminium sheet is significant since this is the most common mode of failure for automotive heat exchangers, especially with the trend toward lighter automotive parts. Furthermore, thermal treatments such as solution heat treatment, homogenization, and brazing alter the microstructure and, as a result, vary the corrosion behaviour. The effect of homogenization temperature and duration on the microstructure of AA-3xxx aluminium alloys has been studied, but more research is needed. The goal of this investigation was to see how different holding times during homogenization heat treatments affect corrosion behaviour. Accelerated laboratory corrosion tests are essential for ranking trial materials and ultimately qualifying an alloy for production. The corrosion behaviour of two-layer modified aluminium sheets (AA4045/3003 Modified) was examined in this research before and after brazing. The corrosion propagation was attributed to potential differences between the brazing sheet, creating a galvanically driven perforation of the core material by the diffusion zone after sea water acid accelerated testing (SWAAT) and electrochemical testing of the AA4045/3003 modified brazing sheet. Furthermore, a link between SWAAT and potentiodynamic polarization measurements has been established, suggesting that these electrochemical approaches could be used to replace or reinforce the SWAAT and so reduce the cost.

Структура быстрозатвердевщих сплавов Al – (0,25 – 2,0) масс.% Bi

The results of study of the microstructure and texture of aluminum alloys, containing 0.25 – 2.0 wt. % Bi, obtained with high speed solidification, are presented. A texture 111 aluminum is formed in the foils. The average chords of bismuth section does not exceed 0.5 μm. The size of dispersed bismuth particles and their number per unit volume of matrix depend on the distance from the foil surface. The specific surface of the aluminum-bismuth interface first increases and then increases as the crystallization front moves. The alloy foils dissolve in water at room temperature, forming hydrogen bubbles and an amorphous powder of aluminum hydrides Al2O3·5(H2O) и Al2O3·3(H2O).

Influence of Welding Parameters on the Mechanical Properties and Microstructure of 7075-T651 Aluminum Alloys Welded Joints Performed by FSW Process

Aluminum alloys of 7xxx series have excellent characteristics and mechanical properties, being widely used in primary aircraft structures. However, the welding of these alloys by conventional arc welding processes results in an excessive mechanical resistance degradation and increasing in residual stress level. In this context, Friction Stir Welding (FSW) process has received attention in recent years mainly because it does not reach the materials melting point during the process. This work aims to evaluate the influence of the tool rotation and welding speed on microstructure and mechanical properties of AA 7075-T651 aluminum alloy welded joints by FSW process. Therefore, four welded joints obtained with different welding and tool rotation speed were subjected to tensile and microhardness tests. The microstructures of the welded joints were evaluated through analysis by optical microscopy and Scanning Electron Microscopy (SEM). The retreating side of the welded joints showed a higher occurrence of microstructural welding defects. Welded joints with yield strength (YS) 50% higher than those of base metal and with ultimate tensile strength up to 380 MPa were achieved.

Microstructure and Properties of Laser Additive Jointing Heterogeneous Aluminum Alloys

Microstructure and Properties of Laser Additive Jointing Heterogeneous Aluminum Alloys

Influence of Sc Micro-Alloying and Low-Frequency Electromagnetic Casting on the Microstructure and Properties of 7a36 Aluminum Alloy

Influence of Sc Micro-Alloying and Low-Frequency Electromagnetic Casting on the Microstructure and Properties of 7a36 Aluminum Alloy

Microstructure of aluminum alloys manufactured via laser powder bed fusion: A review

Laser powder bed fusion (LPBF) enables layer-by-layer manufacturing and provides distinguished microstructure compared with conventional processing methods. Microstructure controlling of LPBF parts requires deep insights into the solidification process. The aim of this article is to review the solidification fundamentals and microstructure characteristics during the LPBF process, and to serve as a guide on how to tailor microstructure for a given part. To clarify the distinguished microstructural characteristics of LPBF parts, casting is briefly discussed for comparison. The article begins with the introduction of solidification theory and microstructure features in LPBF and casting. Thereafter, the attempts to tailor microstructure in LPBF and casting are addressed and compared. The final part of this paper provides an outlook on the remaining challenges and potential research topics of microstructure controlling in LPBF with Al alloys.

Influence of cold pre-deformation on the microstructure, mechanical properties and corrosion resistance of Zn-bearing 5xxx aluminum alloy

The effect of cold pre-deformation combined with ageing treatment on age hardening behavior and associated intergranular corrosion (IGC) resistance of an Zn-bearing 5xxx aluminum alloy is investigated in this study. Results reveal that the strength of the alloy is improved greatly by the prior cold deformation basing on the synergistic effect of work hardening and ageing strengthening. With the combination of cold pre-deformation and ageing treatment, the peak yield strength of the alloy is 314.7 MPa, which increases by 110% than that of the T6 treated alloy. Moreover, the intergranular microstructure such as grain boundary precipitates can be optimized by coordinating the pre-deformation and ageing treatment. Hence, Al–Mg–Zn alloy with high strength and excellent IGC resistance can be obtained by combining the prior cold deformation and ageing treatment.

Effect of main elements (Zn、Mg and Cu) on the microstructure, castability and mechanical properties of 7xxx series aluminum alloys with Zr and Sc

In this study, a series of Al-Zn-Mg-Cu alloy with different compositions added with Zr and Sc refiners are designed. The effect of main alloying elements (Zn, Mg, and Cu) on the grain structure, hot tearing performance, and mechanical properties of the alloy were investigated. It was found that as the content of alloying elements increases, the grain size becomes finer, the grain morphology changes from equiaxed crystal to fine dendrite, and the eutectic phase increase. The maximum and minimum hot tearing susceptibilities of the alloy occur for Zn in 9 and 5%. The hot tearing sensitivity of the alloy is greatly affected by the latent heat of the alloy, the viscosity, and the surface tension of the alloy. The alloying feeding performance is good because of the high content of the non-equilibrium eutectic phase while the alloying content is high. It could be concluded that the mechanical property of the alloy increases while the elongation decreases significantly as the content of alloying element increases. When the Zn content exceeds about 9%, a lot of non-equilibrium eutectic phase remains after heat treatment that resulting in a decrease in the strength and elongation of the alloy. • The new 7xxx alloy has high strength for near-final forming. • The higher the alloying element content, the smaller the grain size. • When the Zn content is about 9%, the alloy has the highest hot tearing sensitivity. • High content of alloying elements, good feeding performance during solidification. • The higher the content of alloying elements, the higher the tensile performance and the sharp decrease in elongation.

The coupling effect of vacuum, pressure and temperature on microstructure and mechanical properties of PM aluminum alloy

The objective of this paper was to assess the coupling effect of vacuum, pressure and temperature on microstructure and mechanical properties of PM aluminum alloy. The results showed that the densification of PM aluminum alloy mainly depended on the powder plastic deformation caused by hot pressing, but the state of particle boundary (PB) was affected by vacuum besides temperature and pressure. When the powder was sintered under high vacuum of 10−3 Pa, the oxide film at PB could be disrupted by pressure, resulting in the formation of narrow regions of metal/metal contact. While under low vacuum of 10−1 Pa, the oxide film coarsened by secondary oxidation was unable to be broken by powder compressing, resulting in residual microcracks and segregation of second phases at the PB. This seriously weakened mechanical properties of PM aluminum alloy. The eutectic liquid formed by increased temperature would make the above process more complex.

Effect of Si Content on the Properties of A356 Aluminum Alloy

The effects of different Si contents on the microstructure and mechanical properties of A356 aluminum alloy were studied by metallographic microscope analysis and tensile property test. The results show that when the silicon content is between 7% and 11 %, with the increase of silicon content, the eutectic silicon in the matrix increases, and the tensile strength and elongation decrease. When the silicon content increased to 13%, the primary silicon structure appeared in A356 aluminum alloy, and its mechanical properties increased.

Effect of Incremental Shrinking Process on Mechanical Properties and Microstructure of Alloy through Electron Backscatter Diffraction Analysis

In recent years, the incremental shrinking process has been widely used in the forming process of aluminum alloy components for the railway vehicles. The effect of the incremental shrinking process on the performance and microstructure of 6082-T6 aluminum alloy was investigated through mechanical tests and electron backscatter diffraction (EBSD) analysis. The tensile test specimens prepared in different rolling orientations (0˚,45˚and 90˚) along the original and deformed sheets exhibited the mechanical anisotropy. After the incremental shrinking process, the average microhardness, tensile strength, and yield strength of this alloy were respectively increased by nearly 8.78%,2.26%,2.72%, while the Elongation was decreased by almost 31.67%. By analyzing the EBSD data, the strength of the material is increased by the incremental shrinking process and its mechanical anisotropy is improved, whereas its plasticity is greatly deteriorated.

Prediction of solidification microstructure of titanium aluminum intermetallic alloy by laser surface remelting

By controlling the processing parameters in the laser additive manufacturing (LAM) process, the mechanical properties of titanium aluminum alloy could be modified. However, the difficulty of optimizing the solidification microstructure is to build the relationship between the microstructure and processing parameters. To solve this problem, a numerical model of combined processing parameters with dendrite arm spacing was developed in this paper to predict the solidification microstructure and reveal the effects of laser processing parameters on dendrite arm spacing. A geometry factor (α) was first introduced in the prediction model to correct the simulated molten pool shape to improve prediction accuracy. Moreover, the nonequilibrium solidification of LAM due to fast cooling was taken into consideration in this study. Based on the model, primary dendrite arm spacing (PDAS) and secondary dendrite arm spacing (SDAS) in laser surface remelting of Ti-47Al-2Cr-2V alloy were investigated in combination with simulations and experimental observations. The experimental results indicate that the model calculated using average solidification conditions applies well in predicting the solidification microstructure of titanium aluminum alloy. The dendrite arm spacing slightly decreases at low scanning velocity but increases at high scanning velocity as the laser power increases. In addition, the scanning velocity plays a dominant role in the change in dendrite arm spacing when the scanning velocity is lower than 600 mm/min, and the impact of laser power on dendrite arm spacing gradually increases as the scanning velocity increases.

The influence of mechanical grinding on the microstructure and corrosion behaviour of A356 aluminium alloys

ABSTRACT In the automotive industry, mechanical grinding is employed at finishing line rectification to remove defects left over from upstream, which may also result in microstructure modification within the near-surface region of the work piece and, consequently, affects its corrosion performance. The present work investigates the influence of mechanical grinding on the microstructure modification and corrosion behaviour of Al–Si–Mg (A356) alloy castings in order to advance the understanding of potential corrosion issues. It is found that a near-surface deformed layer with a maximum thickness of 3 μm, characterised by ultrafine equiaxed grains of 50–150 nm diameter, is introduced by the grinding process on α-aluminium matrix. The near-surface deformed layer has a significant impact on the corrosion behaviour of the alloy; specifically, preferential dissolution of the near-surface deformed layer occurs when exposed to NaCl solution, together with trenching of the aluminium matrix around the eutectic silicon particles.

Effect of pulse frequency on weld appearance of Al alloy in pulse power ultrasonic assisted GMAW

This paper investigated the effect of pulsed power ultrasonic on the appearance, microstructure and mechanical properties of aluminum alloy using self-developed pulsed power ultrasonic wave assisted gas metal arc welding (PU-GMAW) device. The feature of the method was to combine arc and pulsed power ultrasonic field coaxially. The results indicated that, compared with conventional GMAW, the weld penetration of PU-GMAW was much increased and the melting area increased by around 49%. Further, weld melting area enlarged as pulse frequency increased. The average hardness of the weld metal of PU-GMAW was about 15 HV higher than that of GMAW. At the end, the mechanism of melting area enlargement and weld penetration enhancement was discussed, which was attributed to the increase of the welding heat input.

Microstructure-based crystal plasticity modeling of AA2024-T3 aluminum alloy defined as the α-Al, θ-Al2Cu, and S-Al2CuMg phases based on real metallographic image

The increase in the strength of the Al–Cu–Mg alloys is to a large extent due to the formation and distribution of submicroscopic θ-Al2Cu and S-Al2CuMg phases in the aluminum (α-Al) matrix, which causes these alloys to have unique properties such as high initial hardening rate. This paper aimed to examine the anisotropic plasticity and flow behavior of the AA2024-T3 aluminum alloy by measuring the distinctive properties of each of the θ-Al2Cu, S-Al2CuMg, and α-Al phases at the micro-level and using a microstructure-based crystal plasticity model during single-strand tensile strength. The real microstructure of AA2024-T3 aluminum alloy obtained from scanning electron microscopy (SEM) was utilized in the calculations using the polycrystalline image processing method of the phases as a Representative Volume Element (RVE). Each phase’s crystal orientations and texture were randomly generated, given the lattice parameters and their crystal structure. The computational results were compared with the experimental data of the AA2024-T3 aluminum alloy tensile test, the data of the crystal plasticity model without considering the microstructure, and the Johnson-Cook model. Given the heterogeneity of the microstructure and crystal orientations of the grains, it was shown that the maximum internal stress under tensile loading occurred along with local hardening in the α-Al phase adjacent to the grains of the θ-Al2Cu and S-Al2CuMg phases, which was about 43300 MPa.

Dislocation density model and microstructure of 7A85 aluminum alloy during thermal deformation

Dislocation density model and microstructure of 7A85 aluminum alloy during thermal deformation

Microstructure, Phase Composition, Substructure and Residual Stress of AK5M7 Aluminum Alloy after its Electrospark Treatment

Microstructure, Phase Composition, Substructure and Residual Stress of AK5M7 Aluminum Alloy after its Electrospark Treatment