A356 Aluminum Alloy Research Articles

A Novel Preparation Method of Composite Bolted T-Joint with High Bending Performance Based on the Prepreg-RTM Co-Curing Process.

A co-curing resin system consisting of 9368 epoxy resin for prepreg and 6808 epoxy resin for resin transfer molding (RTM) was developed. A corresponding preparation method for a novel polymer composite bolted T-joint with internal skeleton and external skin was proposed based on the prepreg-RTM co-curing process, and novel T-joints were fabricated. A series of conventional configuration T-joints based on the RTM process and T-joints made of 2A12 aluminum alloy were prepared simultaneously. Bending performances were studied on these T-joints experimentally. The results indicate that 9368 epoxy resin and 6808 epoxy resin exhibit good compatibility in rheological and thermophysical properties. The novel T-joints prepared with the prepreg-RTM co-curing process show no obvious fiber local winding or resin-rich regions inside, and the interface quality between the internal skeleton and the external skin is excellent. The main failure modes of the novel T-joint under bending load include the separation of the skin and skeleton and the fracture along the thickness on the base panel; the skeleton carries the main bending load, but there is still load transfer between external skin and internal skeleton through their interface. The internal damages of the novel T-joint are highly consistent with surface damages observed visually, facilitating the detection and timely discovery of damages. The initial stiffness, damage initiation load, and ultimate load of the novel T-joint are 1.65 times, 5.89 times, and 3.45 times that of the conventional T-joint, respectively. When considering the influence of the density, the relative initial stiffness and relative ultimate load of the novel T-joint are 1.44 times and 2.07 times that of the aluminum alloy T-joint, respectively.

Nonlinear analysis model of the progressive damage of aluminum–wood sandwich structures under high-speed impact conditions

The impact responses of various protective structures composed of 2A12 aluminum alloy and wood laminates were studied experimentally. The experiments were conducted using different impact energies. By varying the sandwich material thickness and using two different bullet shapes, the effects of the sandwich material’s damage process and the core layer thickness on the protective performance were studied. The multilayer structure’s core layer failure condition was determined using the improved 3D Hashin criterion and a finite element model was established using Abaqus software. Tensile and three-point bending tests were conducted and the progressive damage model was verified statically. The model was then verified dynamically using the Hopkinson bar test. The mechanical properties of the materials under high dynamic strain rates were obtained through action loading testing of the specimens at different loading rates. The loading waveform was analyzed and a stress-strain relationship diagram was drawn at various strain rates. By verifying the experimental data, a numerical model that could capture the deformation and failure details during crushing was established, and the composite target plate impact failure mode and the trajectory change law were described. This study could lead to use of a new impact damage prediction method for laminates.

Mechanical responses and microstructure evolution of a 7A09 aluminum alloy extrusion profile during novel stretch bending

This paper proposes a new stretch bending approach for aluminum alloy extrusion profiles based on a novel pre-hardening forming (PHF) process. Tensile tests were carried out to examine the flow behavior and mechanical responses of a 7A09 extrusion profile in PHF process. Microstructure evolution was investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), and small angle X-ray scattering (SAXS). It is interesting to find that the yield stress at 200 °C was higher than that at 185 °C. The quantitative analysis revealed that the higher volume fraction of precipitates (200 °C) played a greater role than the refinement of precipitate sizes (185 °C) in precipitation strengthening mechanism, thereby causing an enhanced hardening effect. This phenomenon indicated that there was a preferred temperature zone for the precipitation behavior in PHF process, and it also explained the lower yield stress at 185 °C than that at 200 °C. Additionally, similar results were also observed in strength of the warm-deformed alloys. The optimal strength (σ/σ0.2=589/517 MPa) can be achieved at 200 °C without subsequent heat treatment, which exceeded the typical strength of 7A09-T6 extrusion. The primary strengthening mechanisms in PHF process were strain hardening and precipitation strengthening, and the warm forming procedure caused a hardening effect, rather than a softening impact as in traditional warm/hot forming procedures.

Influence of Various Melt Shearing Speeds on Macrostructure, Microstructure, and Tensile Properties of A380 Aluminum Alloy

Influence of Various Melt Shearing Speeds on Macrostructure, Microstructure, and Tensile Properties of A380 Aluminum Alloy

Improving the Wear Resistance Properties of 7A04 Aluminum Alloy with Three Surface Modification Coatings

Multiple advantages, such as good formability, high specific strength, excellent thermal conductivity, and high corrosion resistance, enable aluminum alloy wide application in various fields; however, low surface hardness and poor wear resistance limit its further development. In this study, three surface modification coatings were successfully prepared on the surface of 7A04 aluminum alloy by microarc oxidation (MAO) and a combination of hard anodizing treatment (HA) and physical vapor deposition (PVD), named MAO, HA+W+DLC, and HA+Ti+ta-C, respectively. The microstructure, hardness, and tribological properties of the three coatings and the 7A04 aluminum alloy substrate were studied. The results show that the surface quality and hardness of the coated samples were higher than those of the 7A04 aluminum alloy and that the HA+Ti+ta-C coating possessed the highest hardness of 34.23 GPa. Moreover, the wear resistance of the two multilayer coatings was significantly improved during the ring-block wear tests under oil lubrication, exhibiting a wear rate of 1.51 × 10−7 mm3/N·m for HA+W+DLC and 1.36 × 10−7 mm3/N·m for HA+Ti+ta-C.

Influence of solid solution treatment on fatigue crack propagation behavior in the thickness direction of 2519A aluminum alloy thick plates

2519A aluminum alloy thick plates have excellent applications in the military industry due to their superior ballistic resistance and fatigue properties. However, the delamination cracking along the thickness direction of this alloy hinders its further utilization. To address this issue and enhance the fatigue properties of this alloy, the effect of single-stage solid solution treatment (SST) and two-stage solid solution treatment (DST) on the fatigue crack propagation (FCP) behavior in the thickness direction of the alloy was investigated. Compared to the optimum SST, the volume fraction of the secondary phase of the alloy was reduced by 28.6% after DST. The precipitated phases were finer with more uniform distribution, and the volume fraction and number density of the precipitation increased by 47% and 30%, respectively. The DST resulted in a lower fatigue crack growth rate (FCGR) and an increase of 2.92% in the critical stress intensity factor value (ΔKcr). The crack propagation mode of the alloy after SST was inter/transgranular crack propagation, while it was transgranular after DST. The aspect ratio of grain and the number of secondary phases in the alloy decrease after DST. Meanwhile, the grain boundary (GB) precipitation phase spacing, the precipitation-free zone (PFZ) width, and the spacing between the secondary phases increase. These changes result in decreased crack sources in the alloy and reduced the bridging effect of secondary phases on fatigue cracks, thus improving the fatigue performance of the alloy.

Effects of pre-stretch on microstructure, mechanical properties and corrosion resistance of 2A14 aluminum alloy

The microstructure, mechanical properties and corrosion behaviors of the peak-aged 2A14 aluminum alloys subjected to pre-stretch prior to artificial aging were investigated. The results indicate that the hardness and strength of the peak-aged alloy can be greatly enhanced via introducing pre-stretch due to the formation of dense and finer θ′ precipitates with dispersed distribution in alloy matrix. Pre-stretch prior to peak aging evidently enhances the peak aging hardness and shortens the peak aging time of the alloy. A pre-stretching degree of 7.5% leads to a distinct inhomogeneous distribution of θ′ phase, which decreases the ultimate tensile strength. As pre-stretching degree increases, the plasticity, impact toughness and exfoliation corrosion (EXCO) resistance of the peak-aged alloy all gradually decrease, but its resistance to intergranular corrosion (IGC) increases and then decreases.

Effect on microstructure and mechanical properties of friction stir welded 5A06 aluminum alloy joints by deep cryogenic treatment

In order to improve the comprehensive mechanical properties of the welded joints of the 5A06 aluminum alloy, friction stir welded (FSW) joints were subjected to deep cryogenic treatment (DCT). The microstructure and mechanical properties were characterised using metallographic microscopy, x-ray diffractometer (XRD), energy spectrometer, microhardness tests, and tensile tests. The experimental results show that DCT refines the structure significantly due to the large temperature difference. This refinement results from an increase in Mg atoms within the α-Al solid solution through the precipitation of Al atoms, forming the Al3Mg2 phase. This enhancement in plasticity is achieved through dispersion distribution. Moreover, as the treatment time of DCT increases, the mechanical properties of the welded joint also improve significantly. The microhardness of the welding joint peaked at DCT3h, rising from 78.8 HV at DCT0h to 87.2 HV at DCT3h. Meanwhile, the tensile strength of the joint reached its maximum at DCT12h, rising from 358.7 MPa at DC0h to 385.3 MPa at DCT12h, representing a 7.4% increase. These experimental results underscore the significant impact of DCT on improving the welded joints.

Optimization of cutting force and surface roughness in end milling of AA-TiCp composite

Nowadays Aluminium alloy (AA) based composites are used in many fields such as automotive, aerospace, electronics, and marine industries. But for the utilization of these composites for different applications with different shapes, machining especially end milling is the essential process. Hence, this work describes the optimization of surface roughness and cutting forces during end milling of A356 aluminium alloy reinforced with titanium carbide particle (TiCp) metal matrix composites (MMCs). A356 alloy with 0, 3 and 6 vol% of TiCp (average size of 50 µm) composites were prepared using a stir casting process. The effects of milling process factors, namely cutting speed, feed, depth of cut, and volume % of TiCp, on average surface roughness (Ra) and cutting forces have been studied using a Box-Behnken design of the experiment technique. The end milling experiments were performed in a CNC vertical machining center without any cutting fluid using uncoated cemented carbide inserts. Using Design Ease software, the predictive model analysis and change in performance measurements for process variables were provided. The results showed that the depth of cut, followed by cutting speed, is the most important criterion and finally optimal levels of process variables were also identified to improve the machinability of the composites.

Texture formation under control of S phase characteristic and tensile property of hot-rolling 2A12 aluminum alloy improved by Brass texture

In this paper, 2A12-T3 aluminum alloy is first solution-treated and then experienced an artificial aging for different time to induce different S phase characteristics. By using this method, the texture formation behavior solely contributed from S phase characteristic could be determined during hot rolling. It is found that the increase of S phase in size and density has a positive effect on Brass texture formation, which is attributive to the increased Dislocation Shear Slipping (DSS) near S/Al interface. The relative slip tendency factor (Msx) is proposed to quantitatively evaluate the impact of S phase characteristic on Brass formation. It is revealed that Brass volume fraction (VBrass) has a better positively linear relationship with Msx than texture intensity. Then, the effect of Brass texture on tensile property is analyzed in details. Crystal plasticity simulation shows that Brass texture can improve the yield stress and tensile strength and simultaneously keep the elongation. Comparatively, the rolling sheet aged for 3 h obtains an excellent combination of strength and ductility.

Effect of Rare Earth La on Microstructure, Hardness and Corrosion Resistance of A356 Aluminum Alloy

Effect of Rare Earth La on Microstructure, Hardness and Corrosion Resistance of A356 Aluminum Alloy

Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C

Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.

Deformation behavior and microstructure characterization of A357 aluminum alloy welding wires used for wire arc additive manufacturing

Microstructure and mechanical responses of A357 aluminum alloy welding wires after different degrees of strain were studied. It is found that the grains are elongated and refined along the drawing direction, accompanying with cell structures and sub-grains with strain increasing. Meanwhile, the main contributions to the fibrous texture are Cube, Goss and Copper, i.e., <001> and <111> textures. With the increase of drawing strain, the volume fraction of the Copper texture first increases and then decreases, while that of the Goss texture increases monotonously. The yield strength sharply increases at low drawing strain, after reaching the maximum value of 144.7 MPa at the strain of 0.32 and it decreases slightly due to dynamic recrystallization. Interestingly, the elongation of the cold-drawn wires decreases steadily from 24.4% to 2.3% throughout the entire drawing process. In addition to the grain boundary strengthening and dislocation strengthening, the yield strength of the cold-drawn A357 wires is also impacted by the <111> texture.

Influence of Y Content and T6 Heat Treatment on the Organization and Mechanical Properties of Cast A356 Aluminum Alloy

The effect of Y content on the microstructure of A356 aluminum alloy and the mechanical properties of the alloy under T6 heat treatment was investigated. The results show that with the addition of 0.3 wt.% rare earth Y, the grain size of the cast A356 aluminum alloy reaches a minimum and the mechanical properties reach an optimum. After the T6 heat treatment, the grain structure of the alloy was further reduced and the mechanical properties were further improved. Compared to the cast A356 aluminum alloy without Y, the average α-Al grain size is reduced by 53.4%, the secondary dendrite SDAS by 32.2% and the average length of eutectic Si particles by 82.0%. The ultimate tensile strength (UTS) and elongation (El) increased to 280.75 MPa and 14.43% respectively, and the Vickers hardness increased to 102.9 HV.

Influence of Tool Pin Profiles on Aluminium Alloy A356 and Ceramic-Based Nanocomposites for Light Weight Structures by Friction Stir Processing

In this research, the main aim is to focus the enhancement of aluminium-based metal matrix composites for improving the attributes of light weight metals, aerospace structures and other tailor blank material properties. By this way, the friction stir processing (FSP) was the suited alternate technique to enhancing the mechanical attributes and superior microstructural amendment in the processed MMCs. Therefore, this study investigates the dispersion of ceramic-based strengthening particles of chromium oxide (Cr2O3) in the aluminium base matrix of A356 alloy. During the processing, the different tool pin sizes having the conical threaded tool pin profiles. Similarly, the tool spinning speed and tool travel speed also varied while in FSP. Before the processing, the A356 alloy was prepared by the grooved surfaces for packing the chromium oxide particles to compose the aluminium metal matrix composites. The tensile strength and hardness was employed to carry out from the friction stir processed A356 alloy with influencing of Cr2O3. The maximum occurred tensile processing parameters are 1500 rpm of spinning speed, 6 mm of tool pin sizes and 90 mm/min of tool travel speed. Similarly, the maximum obtained hardness processing parameter are 2000 rpm of spinning speed, 5 mm of tool pin sizes and 90 mm/min of tool travel speed. A scanning electron microscope was utilized to investigate the dispersed Cr2O3 in the A356 alloy for confirming the refinement grains in the nugget zones of FSPed A356 alloy. The increased grain boundary by the influence of different tool pin sizes was the major reason to produces the better mechanical properties in the processed A356/Cr2O3.

The investigation of Bacillus cereus induced degradation of passive films of 5A06 aluminium alloy in simulated condensate solutions of space station

Microbiologically influenced corrosion in water recovery system of manned spacecrafts deserves attention. The effect of Bacillus cereus on the corrosion of 5A06 aluminium alloy in simulated condensate solutions of space station was investigated. The organic acids induced significant dissolution of aluminium alloy, electrochemical measurements results showed living cells could weakened the cathode reaction, and focused ion beam-scanning/transmission electron microscopy indicated that B. cereus cell promoted the thinning of passive films. B. cereus affected the corrosion of 5A06 AA through metabolic activities and extracellular polymeric substances, ultimately promoting the degradation of passive films of aluminium alloy.

An Experimental Investigation of the Material Properties of the A356 Aluminum Alloy Power Fittings in the Vacuum Die-Casting Process.

To enhance the performance of ultra-high voltage power fittings in severe weather conditions without altering their current structure, the high-strength and toughness aluminum alloys were rationally selected to study the optimization of the die-casting process. This approach aims to improve the overall longevity and function of the power fittings in extreme climates. First of all, the propose of this study is to use the material's strength-toughness product (STP) concept to evaluate the material stability of the power fitting impact resistance and fatigue toughness in order to determine the appropriate material selection. Secondly, the location of the mold's sprue and gate was optimized through finite element simulation to prevent gas volume and flow defects during the casting process. This improves the material's toughness and anti-fatigue failure characteristics of the product. Then, vacuum equipment and a vacuum valve auxiliary system were added based on the existing die-casting machine, and the mold structure was optimized to enable the vacuum die-casting process. Finally, a water-based boron nitride environmentally friendly mold release agent was used to solve demolding difficulties with an A356 aluminum alloy and improve mold lubrication and surface quality. The production of quad-bundled spacers using A356 and vacuum die casting has resulted in parts with a tensile strength of at least 250 MPa and an elongation of no less than 7%. This improvement has laid a foundation for enhancing the operational reliability of existing overhead transmission line fittings.

Simultaneous reduction in laser welding energy consumption and strength improvement of aluminum alloy joint by addition of trace carbon nanotubes

The widespread use of laser welded aluminum alloys in industrial production offers potential benefits to sustainable development and socio-economic progress. It simultaneously enhances the weld strength while reduces the energy consumption. Despite the promise of these alloys, research on reducing their energy consumption during laser welding is lacking. In this study, a dual effect of enhancing joint strength in 2A12 aluminum alloy and reducing energy consumption is achieved by the addition of trace carbon nanotubes (CNTs). The “welding efficiency" is defined and an energy consumption model for laser welding of aluminum alloys is developed. Next, the laser welding process with the addition of trace CNTs (LC) and the single laser welding process (LW) were compared and analyzed. The results indicate that adding trace CNTs can reduce energy consumption by more than 33 % and increase joint strength by 101 MPa. Furthermore, it is found that the LC process offers significant energy-saving advantages over other laser welding of aluminum alloy processes described in previous studies. These improvements is attributed to the increased laser absorption by the aluminum alloy induced by trace CNTs, as well as their residual presence in the joint, which acts as a strengthening medium. This work provides new insights and presents a novel approach for achieving low-carbon, high-quality welding of aluminum alloys.

Mechanical properties of ultrasonic welded and self-piercing riveted joints in a 5A06 aluminum alloy and a TA1 titanium alloy

Abstract The self-piercing riveting (SPR) experiences problems of poor forming qualities and mechanical properties during joining aviation alloy sheet materials. To address this issue, a novel combined process nominated ultrasonic self-piercing riveting (USPR) is carried out to join a 5A06 aluminium alloy and a TA1 titanium alloy sheets. The forming qualities, mechanical properties, failure modes, and mechanisms of USPR and SPR joints are comprehensively investigated. The results showed that the mechanical properties of the USPR joints were enhanced due to the welding formation of a solid phase between the specimen sheets and the degree of solid phase. The investigation showed that the welding was mainly affected by the material of the upper sheet. However, the welding also increased the brittleness of the rivet to some extent. The failure modes of the joints are affected by the welding process. The results determined that APL, AFD, and AEA of USAA joints were improved by 25.6 %, 31.3 %, and 88.8 %, respectively. The performance of the USPR joints with 5A06 aluminum alloy as the upper sheet is improved more than 88.8 % after the welding process. The combined method can be advantageous and supportive for automotive and spacecraft applications.

Numerical simulation of spinning forming of A356 aluminum alloy hub using dual spinning rollers

A finite element model of one-pass forming of an A356 aluminum alloy hub using dual spinning rollers was established, and the effectiveness of the finite element model was verified through experiment. The established finite element model was used to study the influence of the feed rate, the spindle speed, the axial distance of the two spinning rollers, and the friction coefficient on the forming quality of the hub. The result shows that a good forming quality could be obtained when the feed rate is 4 mm/s, the spindle speed is 220 rpm, the axial distance between the two spinning rollers is 3 mm or 7 mm, and the friction coefficient is 0.2. The simulation results can provide a reference for actual spinning production processes.