Alloy A356 Research Articles

Joining Aluminium Alloy 5A06 to Stainless Steel 321 by Vaporizing Foil Actuators Welding with an Interlayer

Direct aluminium–stainless steel joints are difficult to create by the vaporized foil actuator welding (VFAW) method because brittle intermetallic compounds (IMCs) tend to form along the interface. The use of an interlayer as a transition layer between the two materials with vast difference in hardness and ductility was proposed as a solution to reduce the formation of the IMCs. In this work, VFAW was used to successfully weld sheet aluminium alloy 5A06 to stainless steel 321 with a 3003 aluminium alloy interlayer. Input energy levels of 6 kJ, 8 kJ, 10 kJ, and 12 kJ were used and as a trend, higher energy inputs resulted in higher impact velocities, larger weld area, and better mechanical properties. In lap-shear and peel testing, all samples failed at the interface of the interlayer and target. At 10 kJ energy input, flyer velocities up to 935 m/s, lap-shear peak load of 44 kN, and peel load of 2.15 kN were achieved. Microstructure characterization and element distribution were performed, and the results show a wavy pattern created between the flyer and interlayer which have similar properties, and the interface between the interlayer and target was dominated by element diffusion and IMCs identified mainly as FeAl3 and FeAl. The results demonstrate VFAW is a suitable joining method for dissimilar metals such as aluminium alloy and stainless steel, which has a broad and significant application prospect in aerospace and chemical industry.

Overageing Characteristics of Alloy A356 and Al-Mg-Si Casting Alloys

Al-Si-Mg casting alloys, such as Al-7Si-0.3Mg alloy A356, are heat treatable and can be precipitation hardened to the T6 temper condition. However, Al-Mg-Si casting alloys (5xx series) are generally not considered to be heat treatable. These 5xx series castings are known for good castability and good resistance to corrosion, especially in marine environments. This paper investigates the extent to which 5xx series alloys could possibly be artificially aged. The influences of artificial ageing time on the overageing characteristics of both Al-Mg-Si and A356 casting alloys have been studied. A356 aluminium alloy castings were produced using the CSIR rheo-high pressure die casting process (R-HPDC). Al-Mg-Si alloys were cast using permanent mould casting. The rate of overageing of these alloys is of importance for potential higher temperature applications. The overageing characteristics of Al-Mg-Si and A356 aluminium alloys have been investigated at an artificial ageing temperature of 190°C for ageing times up to 128 hours. It is shown that the rate of overageing of Al-Mg-Si casting alloys is lower than for alloy A356. This could possibly result in the use of these alloys in applications at temperatures that are higher than where alloy A356 can be employed. It also allows the possibility of using the 5xx series alloys as an alternative to other Al-alloys for R-HPDC applications.

Interconnection of Structural Characteristics with Dynamic Properties of A5083 Aluminum Alloy

Abstract—In this work, the resistance of high-strain rate deformation and fracture during shock-wave compression of aluminum alloy A5083 previously obtained in two structural states by torsion under high pressure or dynamic pressing is studied. It is shown by electron microscopy that sub-microcrystalline structures differ in the size of grain–subgrains, dislocation density, and ratio of low-angle and high-angle boundaries. It is established that, at the same grain size, the sub-microcrystalline alloy exhibits higher dynamic properties, and after dynamic pressing, it has higher spall strength.

Finite Element Simulation and Experimental Investigations on Flow behavior of Aluminum Alloys in Equal Channel Angular Pressing

Abstract The paper presents the Finite Element (FE) simulation of the flow of Aluminium alloy A357 through different Equal Channel Angular Pressing (ECAP) dies. The simulation involves creating a material model using user subroutines in ABAQUS to numerically analyze the flow behavior of the material. The viscosity and shear strain rate variations are presented for two different die configurations by varying the ram speeds and friction conditions. Sudden peaks in strain rate attributes to the rise in strain caused due to the channel angle of the die and fall in viscosity of the material under investigation. The obtained results thus validates the numerical model and are compared with the experimental results

Ultrasonic treatment: a clean technology that supports sustainability in casting processes

The casting process is one of the most important steps in the production and supply chain of metallic components. Certain aspects, such as a clean melt, a finely clustered microstructure, and homogeneous solidification, are the basic requirements for making high-quality components and therefore influence all subsequent production stages. Current procedures to fulfill these requirements are the use of additional chemical substrates and stirring units, as well as energy-intensive technologies for cooling and tempering the molds. The goals of this work can be summarized as the development and investigation of a new ultrasonic treatment (UST) applied during the solidification of the aluminum casting alloy A356. The main idea is to expand the well-known physical effects of UST by exploiting the possibility of influencing microstructure formation during solidification. From the viewpoint of industrial applicability, the contribution of this work is the presentation of a new simulation tool that allows for making comprehensive predictions of UST processes. The presented results confirm the huge potential of the proposed treatment for increasing strength, reducing wall thicknesses, and saving valuable resources, such as materials and energy.

Fractal Characterization of Relative Movement Modes in Simulated Friction and Wear Tests

The selection of the relative movement mode between the friction pairs in simulated friction and wear tests is a crucial factor for the characterization and evaluation of metallic material properties. In this study, two kinds of commonly used metal materials (stainless steel 0Cr18Ni9 and aluminum alloy 2A12) were applied for the simulated friction and wear tests with four different modes of relative motion, including unidirectional, reciprocating, circular and multi-directional cross-shear. The corresponding surface topography and statistical parameters such as surface roughness Ra were obtained via OLYMPUS ultra-depth microscope. Based on the fractal theory, fractal dimension D was calculated to characterize the surface topography and the results indicate that, the fractal dimension D of the unidirectional and multi-directional cross-shear simulated friction and wear tests is the minimum and maximum respectively, which reflects that the fractal dimension D is able to characterize the complexity of the surface morphology. The fractal dimension D may be related to the intrinsic physical properties of metal materials, such as hardness and toughness, which needs to be further studied.

Friction Drilling of Cast Aluminum Alloy A380 Without Significant Petal Formation and Radial Fracture

Cast aluminum alloy A380 is one of the most commonly specified alloys that has light weight and exhibits excellent resistance to hot cracking, which makes it necessary in many industrial applications. An idea is investigated to generate a cylindrical bushing without significant petal formation and radial fracture that are expected to be obtained by friction drilling of cast metals. Three materials; namely, 316 stainless steel, Al6060 aluminum alloy, and red copper alloy are used in which each of them is located on the upper and lower surfaces of A380 workpiece, so achieving the idea of the functionally graded material. The process parameters were studied for reducing the resultant axial force, the gap between surfaces, and achieving a longer bushing without petal formation and radial fracture. Lower feed rate achieves minimum axial force and gap thickness with maximum bushing length for all material sandwiches. An optimized decision making by the help of fuzzy logic techniques is performed, revealing that red copper sandwich exhibits the optimal multiple performance characteristic index based on axial force, bushing length, gap thickness, and gap divergence.

The assessment of modified block samples for the investigation of impact strength of adhesive joints

The described research relates to the methodology of block bonded joints, dealing with one of its aspects. The authors made an experimental comparison of samples for the research into impact strength of adhesive joints which differ in the shape and the height of the upper element. The experimental testing was carried out with an impact dropping tool, designed to examine adhesive joints. The maximum energy of the pendulum used in the research was 15 J. The elements of the samples were made of steel S235 or aluminum alloy 2017A. In order to bond the samples, the authors used Epidian 57 epoxide resin with Z1 hardener or the Loctite EA 9450 adhesive. The authors examined samples with upper element rectangular, 3 mm high or disc ones - 3, 5 and 7 mm high. The surface area of the adhesive joints in the tested samples equalled 125 mm2 or 250 mm2. In the research, the authors focused on the determination of specifying the optimum height of the application of the load and the height of the sample which has a circular cross-section, at which the plastic deformation will not affect the stress distribution in the joint.The analysis shows that the impact strength of the tested joints depends on the shape of the tested joint (adhesive joint). With the same surface, connections to the upper disk-shaped element are twice as strong as those made according to the ISO 9653 standard.The impact strength of the modified block sample with upper disk-shaped element significantly depends upon the distance from the edge of the impactor to the surface of the adhesive joint. The conducted studies and analyses show that these could be the following values: 5 mm and 2.8 mm.

Two-Step Aging Behaviour of Solution Treated A356 System Alloy

Al-7mass%Si-0.3mass%Mg alloy is widely applied to the automotive components, such as road wheel or suspension frame because of having higher ductility and corrosion resistance. Two-step aging behavior of solution treated Al-7mass%Si-0.3mass%Mg system alloy A356 cast into permanent mold and solution treated was investigated by micro-vickers hardness measurement, optical microscopy (OM) and transmission electron microscopy (TEM). The microstructure of as-cast state was consist of primary crystallized α-Al and secondary crystallized eutectic phases. Al-7mass%Si-0.3mass%Mg alloy after casting, the test specimens were heat treated for different pre-aging temperatures at 273K, 348K and 423K for various times after solution treatment at 813K for 36ks. After pre-aging treatment, the test specimens were heat treated for artificial aging at 523K for various times. The peak hardness increased almost the same value when the pre-aging temperature was 273K. On the other hands, positive effect of the final-aging was occurred after pre-aging at 348K and 423K with significantly increasing hardness in the under-aging region. The fine precipitates were observed in the specimen which was final aging at 523K after pre-aging at 348K and 423K.Such a positive effect is considered due to the influence of precipitated phase mainly such as clusters and /or G.P.zone.The present study aims to investigate the effect of pre-aged temperature on final-aged behavior in A356 system alloy.

Hot corrosion studies of HVOF sprayed carbide and metallic powder coatings on alloy 80A at 900 °C

The current work compares the high temperature corrosion behavior of alloy 80 A coated with carbide (Cr3C2-25NiCr) and Metallic (NiCrMoNb) powders through high velocity oxy-fuel (HVOF) process, under 50 cyclic condition at 900 °C. The corrosion study was conducted in the air oxidation environment and molten salt environment. The coating thickness, hardness, and porosity were assessed along the cross section direction. The results of thermogravimetry analysis showed that the substrates subjected to air oxidation environment showed a lesser mass gain, in comparison to its molten salt environment substrates (uncoated and coated substrate) and it trails the parabolic rate law of oxidation. The uncoated substrate had shown excellent corrosion resistance, whereas poor corrosion resistance was observed in the metallic powder coated substrate in the molten salt (Na2SO4 + 60% V2O5) environment. The existence of MoO3 phase reduced the corrosion resistance of the metallic powder coated substrate. The existence of NiCr2O4 and Cr2O3 phases observed on Cr3C2-25NiCr coating provided good resistance to hot corrosion in the molten salt environment.

Experimental Investigation and Evaluation of Joint Strength of A356/Mg Bimetallic Fabricated Using Compound Casting Process

In the present work, two lighter materials (pure magnesium and aluminum alloy A356) were joined together by vacuum-assisted sand mold compound casting process. The dominating process parameters such as pouring temperature, insert temperature, surface roughness of insert and vacuum pressure were chosen to execute the casting process. Microstructure of joint interface was analyzed by SEM, EDS and XRD techniques. Mechanical properties, namely, microhardness, impact and shear strength of joint, were measured experimentally. The accuracy of experimental data was checked by using response surface methodology. The joint strength of A356/Mg interface was evaluated by applying graph theoretic approach (GTA). A numerical value, joint strength index, was proposed to show the effect of factors and subfactors. Index values of subsystems revealed that shear strength has maximum influence on joint strength followed by microhardness and impact strength. GTA proves an effective tool in estimating the optimum process parameters for compound casting process.

Fractal Analysis of the Influence of Mesh Number of Sandpaper on Simulated Wear Process

The analysis of worn surface topography is an important approach to study the wear mechanism of friction pairs. The influence of mesh number of sand paper on simulated wear process was investigated based on fractal theory. The results indicate that cross-shear wear mode is appropriate for simulated wear, which is close to actual working condition and the resultant surface morphology has fractal characteristics. With the increase of the mesh number of sandpaper, the surface roughness Ra of stainless steel 0Cr18Ni9 and aluminum alloy 2A12 decreased while the fractal dimension D increased and showed a general linear relationship. However, the surface roughness Ra and fractal dimension D of the stainless steel were slightly greater than that of the aluminum alloy. Fractal dimension D may be related to the intrinsic physical properties of metallic materials and could be used to characterize the relative machinability of materials.

The Response of Some Properties of (Al-Si-Mg) Alloy to Nano-Ceramic Materials’ Addition

Al-Si alloys which are widely used in engineering applications due to their outstanding properties can be modified for more enhancements in their properties. Current work investigated the ability of these alloys to be modified by casting them through the addition of nanoparticles. So, Multi-wall carbon nanotubes (CNT) and titanium carbide ceramic particles (TIC) with size of (20 nm) were added with different amounts started from (0.5 up to 3%) weight to cast alloy A356 that was considered to be the base metal matrix, then stirred with different speeds of (270, 800, 1500, 2150) rpm at 520 °C for one minute. The results showed change in microstructure’ shape of the casted alloys from the dendritic to spherical grains with increasing stirring speed. Also, EDX analysis confirmed the existence of CNT and TIC additions over inter-dendritic locations related to the affected area. However, the enhancement in the mechanical properties for both types of castings was gained at a weight of 2.5% and a stirring speed of 1500 rpm.

Impact test simulation and structural optimization of aluminum alloy A356.2 wheel hub

In order to improve the design efficiency of automobile hub, finite element simulation analysis is performed on the impact test of automobile hub. According to the national standard of impact test, Ansys Workbench software is used to load and constrain the explicit dynamics elastoplastic model. According to the results of impact strength analysis, the deficiency of the structure is studied, and put forward the corresponding structural optimization design. The actual test verifies the accuracy of the impact test simulation. Ansys software is used again to analyse the impact stress of the improved wheel hub to verify the rationality of the improved structure. The experimental results show that the method of dynamic analysis is practical and effective in calculating the stress and strain of automobile hub impact test. The research results provide theoretical basis and practical significance for the design and development of automotive aluminum alloy wheels.

Multiaxial fatigue life estimation of defective aluminum alloy considering the microstructural heterogeneities effect

The Al–Si–Mg high-cycle fatigue behavior is mainly affected by the microstructural heterogeneities and the presence of casting defects. This attempt aims to develop an analytical approach based on the evaluation of the highly stressed volume caused by local porosities and defined as the affected area methodology. The proposed approach is able to predict the aluminum alloy fatigue response by considering the effect of microstructure described by the secondary dendrite arm spacing and its correlation with the defect size effect. A representative elementary volume model is implemented to evaluate the stress distribution in the vicinity of the defect and to determine its impact on the high-cycle fatigue resistance. Work hardening due to cyclic loading is considered by applying the Lemaitre–Chaboche model. The Kitagawa–Takahashi diagrams corresponding to different microstructures and for two loading ratios: R σ = 0 and R σ = −1 were simulated based on the AA method. Simulations were compared to the experimental results carried out on cast aluminium alloy A356 with T6 post heat-treatment. The results show clearly that the proposed approach provides a good estimation of the A356-T6 fatigue limit and exhibits good ability in simulating the Kitagawa–Takahashi diagrams for fine and coarse microstructures.

Development of welding technique to suppress the microsegregation in the aerospace grade alloy 80A by conventional current pulsing technique

Alloy 80 A is prone to hot cracking during conventional arc welding process. Microsegregation of alloying element Cr lead to the formation of M23C6 carbide phase during solidification of fusion zone, and it contributes to hot cracking. The current study employs different welding techniques and filler wires to minimize the microsegregation. The weldments were fabricated by Gas Tungsten Arc Welding (GTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW) techniques using filler wires 263 and ERNiCrMo-3. Scanning electron microscope (SEM) reveals the existence of secondary phase in the interdendritic region for all the weldments. Energy dispersive X-ray spectroscopy (EDS) analysis reports that PCGTAW eliminates microsegregation of Cr precipitate and suppress Nb and Mo precipitates better when compared to GTAW. X-ray Diffraction (XRD) analysis indicate the presence of M23C6 Cr and Mo-rich carbide phase in GTA weldment of 263 filler wire. Whereas in PCGTAW, NiCrCoMo phase is observed. In both GTAW and PCGTAW of ERNiCrMo-3, the intermetallic phases Ni8Nb and Cr2Ti are observed. The tensile test was conducted to assess the strength and ductility of the weldments. The results of the PCGTAW weldments have improved compared to their respective GTAW weldments.

Numerical simulation of cavitation behavior and peening experiments in cavitation peening processing

The software, Fluent, was used to analyze the cavitation behavior of the submerged water jets generated by contraction nozzle, angle nozzle and organ pipe nozzle. Angle nozzle was chosen for cavitation peening based on the results of numerical simulation. The cavitation peening experiments for aluminum alloy 2A12 were conducted with the different processing parameters. The surface roughness, residual stress distribution and morphology of the treated sample surface were investigated. Results show that the distribution of strengthening area is consistent with that of simulated cavitation bubbles cluster. Using the optimized parameters, the surface residual compressive stress and its depth reach the maximum values of 320MPa and 390μm, respectively, which were increased nearly 2.7 times and 5.5 times than those of the original sample, respectively, while the corresponding surface roughness was only 1.29μm, which was much smaller than that of conventional shot peening.

Development of fatigue analytical model of automotive dynamic parts made of semi-solid aluminum alloys

Abstract Automotive suspension control arm is used to join the steering knuckle to the vehicle frame. Its main function is to provide stability under fatigue stresses of loading and unloading in accelerating and braking. Conventionally, these parts were made of steel; however, fuel consumption and emission of polluting gases are strongly dependent on car weight. Recently, there is a try to develop and design much lighter and better fatigue resistant metal of semisolid A357 aluminum alloys. This work aims at a better understanding of identifying the fatigue strain-hardening parameters used for determining fatigue characteristics of aluminum suspension control arm using analytical and mathematical modeling. The most judicious method is to perform the fatigue tests on standardized test pieces and then plot two Wohler curves, mainly number of cycles as a function of the stress and as a function of the deformation. From these curves and following a certain mathematical and analytical methods, certain curves are plotted and then all of these coefficients are drawn. The new calculated parameters showed a clear improvement of the fatigue curve towards the experimental curve performed on the samples of aluminum alloy A357 compared with the same analytical curve for the same alloy.

Experimental optimisation of the tribological behaviour of Al/SiC/Gr hybrid composites based on Taguchi’s method and artificial neural network

This paper presents the investigation of tribological behaviour of aluminium hybrid composites with Al–Si alloy A356 matrix, reinforced with 10 wt% silicon carbide and 0, 1 and 3 wt% graphite (Gr) with the application of Taguchi’s method. Tribological investigations were realized on block-on-disc tribometer under lubricated sliding conditions, at three sliding speeds (0.25, 0.5 and 1 m/s), three normal loads (40, 80 and 120 N) and at sliding distance of 2400 m. Wear rate and coefficient of friction were measured within the research. Analysis of the results was conducted using ANOVA technique, and it showed that the smallest values of wear and friction are observed for hybrid composite containing 3 wt% Gr. The prediction of wear rate and coefficient of friction was performed with the use of artificial neural network (ANN). After training of the ANN, the regression coefficient was obtained and it was equal to 0.98905 for the network with architecture 3-20-30-2.

Effect of Process Variables on Microstructure of Cast Aluminum Alloy A356 during the Friction Stir Processing

Effect of Process Variables on Microstructure of Cast Aluminum Alloy A356 during the Friction Stir Processing