A356 Aluminum Alloy Research Articles

Attention Pyramid Dilated Region-based Model for Metallurgical Defect Detection

Abstract Defect recognition is the key to realizing automatic visual inspection and quality control in intelligent manufacturing. Deep learning (DL) has been widely applied to locate damaged areas in images, characterize impurities of materials and further analyze the quality of products. However, automatic defect detection by DL in practical industrial applications is still a challenge due to the lack of sufficient datasets and appropriate recognition methods. Here, a novel Attention Pyramid Dilated Region-based Convolutional Neural Network (ADRCNN) is proposed to realize the multi-scale defect recognition and pixel-level instance segmentation of metallographic images. We also collected a dataset containing 900 images of commercial A356 aluminum alloy with different casting defects. The ADRCNN model is evaluated on our dataset with an average detection accuracy of 87.2% and 93.3% on validation and test sets respectively. To address the overfitting problem, a pretraining fine-tuning strategy is implemented by using the pretraining weights from large-scale datasets and temporarily freezing the weights of the backbone network during the training process. The experimental results show that the proposed model can achieve satisfactory defect segmentation in metallographic images, promoting the development of intelligent manufacturing in alloy industries.

Formation of seaweed morphology and enhancing mechanical properties of an A356 alloy by directional solidification

In the present work, regular dendrite and seaweed pattern are produced by controlling the crystal orientation during directional solidification of an A356 aluminium alloy. These morphologies and growth orientation were investigated by electron backscatter diffraction (EBSD), and the results showed that the seaweed pattern mainly prevailed under the (100)[011] orientation. At the same time, the effects of seaweed pattern in the properties of A356 alloy were analysed by room temperature tensile test. It was found that the elongation and toughness of the samples reached 20% and 36J/m3, respectively, for the seaweed; 13% and 24J/m3, respectively, for the regular dendrites; and 8% and 14J/m3, respectively, for the cast ingot. Compared with the regular dendrite samples, the seaweed pattern obtained relatively excellent elongation and toughness. By using scanning electron microscopy (SEM), it is found that the distribution of eutectic silicon particles in seaweed morphology sample is more refined and uniform, which is the main reason for these enhancements.

Shape of fragments cloud behind heterogeneous screen by a space debris particle impact

Technogenic pollution of near-Earth space poses a threat to the functioning of spacecraft. Collisions between space debris (SD) and spacecraft (SC) structures can have catastrophic consequences or cause localized damage, leading to the loss of SC operability or the failure of certain functions. The SC body must effectively protect the internal equipment from various external impacts, be technologically feasible to manufacture, and have as little mass as possible. As a result, the task of designing spacecraft bodies and protective screens for low-orbit SC is particularly relevant due to the large concentration of SD in low Earth orbits.A comparative numerical study was conducted to evaluate the effectiveness of various thin shields in protecting against impacts from space debris particles. The study examined homogeneous shields made of A356 aluminum alloy and 316L stainless steel, as well as volumetrically reinforced composite shields produced using additive manufacturing with steel inclusions, and shields with a gradient distribution of steel throughout the thickness of an aluminum matrix, all with the same areal density. In all the heterogeneous plates considered, the volumetric concentration of steel was 36 %. The study covered an interaction velocity range of 2–9 km/s. Numerical modeling results indicated that the structure of the thin heterogeneous plate does not affect the shape of the debris cloud formed behind the protective shield. The findings of this study can serve as a basis for selecting materials for the development of more effective protection for spacecraft against high-velocity impacts.

Effects of nanoceramic particle size and content on the wear resistance of micro-arc oxidation coatings for 2A12 aluminum alloy

The 2A12 aluminum alloy, renowned for its exceptional mechanical properties, encounters significant limitations in applications involving abrasive environments or frequent contact with other surfaces due to its inadequate wear resistance. This shortcoming substantially reduces the service life of components and escalate maintenance costs, highlighting the urgent need for advanced surface modification techniques. This study meticulously investigates the influence of nanoceramic particle size and content on the wear resistance of micro-arc oxidation (MAO) coatings, a surface modification technique renowned for forming dense, adherent ceramic layers on aluminum alloys. The systematic experimentation revealed that the incorporation of 150 nm α-Al2O3 nanoparticles into the MAO matrix achieves an optimal dispersion, leading to a substantial enhancement in wear resistance. The sample with a 5 g/L concentration of 150 nm α-Al2O3 nanoparticles doping in the MAO electrolyte demonstrated the lowest mass loss, underscoring its enhanced wear resistance. The enhanced microstructure, enriched with hard ceramic phases such as α-Al2O3 and mullite, plays a pivotal role in withstanding wear. Moreover, this study identified that an optimal balance of surface roughness and coating thickness is essential for achieving enhanced wear resistance. The findings of this research provide a strategy for the design of wear-resistant coatings tailored for high-performance applications across aerospace, automotive, and general engineering industries. By optimizing the particle size and concentration in MAO coatings, this study paves the way for the development of durable materials capable of thriving in demanding environments, thereby extending the service life and reducing maintenance requirements of components.

Study on the fatigue performance and Residual Stress of subsurface fluid flow of 2519a aluminum alloy based on water jet peening

In this study, the influence mechanism of water jet (WJ) strengthening on the surface integrity and fatigue properties of 2519 aluminum alloy was investigated by using finite element software Abaqus 2023 and fatigue analysis software Fe-safe. The effects of jet velocity and transverse velocity on the development of surface roughness and residual stress in different strengthening stages were studied, and the fatigue properties of WJ strengthened samples were analyzed by Fe-safe fatigue software. Finally, the fatigue life and fracture morphology of WJ strengthened specimens were analyzed by fatigue test, and the accuracy of finite element analysis was verified. Results indicate that surface roughness post-WJ enhancement displays a “W” shaped distribution, positively correlated with jet velocity. Conversely, increased roughness negatively correlates with higher traverse speeds, with optimal values recorded between 400 and 600 mm/min at WJ-290 mm/s, ranging from 1.10322 to 1.41167 μm. Additionally, the study reveals that maximum residual compressive stress during the WJ-Ip phase correlates positively with jet velocity, peaking at 302 MPa for WJ-290 mm/s. The research also notes that while higher jet velocities enhance residual compressive stress, they simultaneously elevate surface roughness, potentially introducing damage and increasing the variability of stress magnitudes. The study underscores the necessity of meticulously calibrating WJ parameters to enhance surface quality effectively while minimizing adverse effects. This balance is critical to optimizing the treatment process and achieving desired material properties.

Study on microstructure and corrosion behavior of T-joints of 2A12 and 2A97 aluminum alloys by FSW

T-shaped joints of high-strength aluminum alloy welded by friction stir welding (FSW) are expected to replace the traditional riveting structures. However, the popularization of FSW in aerospace industry is still hindered the corrosion of T-joint. Herein, T-joints of 2A12 and 2A97 aluminum alloys are prepared and studied via structural characterization and corrosion tests. The microstructures and constituents of different micro zones in T-joints before and after corrosion tests are characterized and analyzed particularly. The internal relationship between different micro zones in T-joints and their corrosion behaviors are clarified, which provides theoretical basis for improving welding process and surface protection after welding.

Coupling effect of dynamic power and oscillation path on butt weld formation and melt flow behavior during aluminum alloys

The influence of the coupling effect between dynamic power and oscillation path on the formation of weld seams and the fluid behavior of the molten pool during laser welding of 5A06 aluminum alloy was investigated through numerical simulation and experimentation. Three power modes were compared in the experiments: equal power (EP), delayed dynamic power (D-DP), and non-delayed dynamic power (ND-DP). The experimental results show that both D-DP and ND-DP modes are favorable to improve the mechanical properties. Among them, the joints formed under the D-DP mode exhibit the best mechanical properties, with an average tensile strength reaching ≈ 99.1% of the base material, which is an increase of ≈ 35.3% and ≈ 5.6% compared to the EP and ND-DP modes, respectively. Numerical simulation results indicate that the D-DP mode effectively mitigates the average flow velocity of the molten pool, reduces the collision effects between liquid flows, suppresses the impact of fluid on the keyhole walls, and improves the stability of the keyhole and the welding process, thereby enhancing the mechanical properties of the joints.

Study on the Effect of Al-Ti-B-RE Refiner on the Refining Effect of A356 Aluminum Alloy after Different Melt Treatments

Abstract The A356 aluminum alloy treated with conventional flux purification and impurity removal flux purification was refined using Al-Ti-B-RE refiner. The aluminum liquid treated with impurity removal flux purification had a better refining effect, with a reduction in grain size of 25.26% and a significant improvement in strength and elongation. Due to the higher purity of the aluminum liquid purified by the impurity removal flux, the stability of the refinement effect is better maintained during the later insulation process, providing good conditions for the transportation and casting of the aluminum liquid.

Proposing novel body-centered cubic lattice core sandwich panels as satellite structure

In the present paper, a comparative study on the load-bearing as well as shielding performance against hypervelocity impact of space debris of sandwich panels with body-centered cubic lattice core is performed numerically in order to evaluate their eligibility to be utilized as the satellite structure. To this end, four types of body-centered cubic lattice structures, with similar areal densities which are assumed to be made of 5A06 aluminum alloy, including BCC, BCCz (BCC reinforced in Z direction), and also BCCz-I and BCCz-II were considered. Whipple shield structure of same material and areal density was also investigated in order to justify the necessity of lattice structures application, especially in protection field. The present study simulates hypervelocity impact of a spherical projectile with 2 mm diameter, represented the space debris, collides with the structures at the velocity range of 2–6 km/s. Current numerical simulation process accuracy and efficiency were verified through comparing its obtained data based on simulating a problem had been investigated at a valid experimental study to the data proposed by the mentioned research. BCCz-II structure which is newly proposed at this study provided outstanding shielding and load-bearing capabilities in comparison to other structures. Furthermore, the detailed effects of projectile impact location and a middle structure placed plate on the protection performance were investigated and the mentioned items were found to have crucial impact on the structure shielding performance.

Study on the Effect of Al-10Sr Intermediate Alloy on the Modification of A356 Aluminum Alloy after Different Purification Treatments

Abstract For three different purification treatment methods of aluminum melt: untreated (UT), conventional purification treatment (CPT), impurity removal flux purification treatment (IRF), and Al-10Sr intermediate alloy was applied for modification treatment. The results showed that due to the highest purity of aluminum liquid treated with IRF, the secondary dendrite spacing decreased by 31.32% after modification, and the eutectic silicon phase was in a granular and dispersed distribution. The tensile fracture exhibited ductile fracture characteristics, effectively improving the mechanical properties of the alloy. At the same time, it was found that reducing the Sr content did not decrease the modifying effect, indicating good purity of aluminum liquid can provide superior melt conditions for subsequent modification treatment.

Optimization of impurity removal and purification flux components and their application in the production of A356 aluminum alloy

Abstract Taking into account the thermodynamic and kinetic conditions of impurity removal and purification, three impurity removal and purification fluxes were designed for comparative experiments. It was found that the impurity and hydrogen removal rates of experimental flux II were the best, with a decrease of 28.1% in micro grain size 28.1 μ m. The spacing between secondary dendrites is significantly reduced. The eutectic silicon phase of the alloy treated with experimental flux II is granular, with small and dispersed inclusions. The fracture structure of the alloy exhibits ductile fracture characteristics, mainly in the form of transgranular microporous aggregation, which helps to improve the plasticity and fatigue resistance of the alloy. The flux purification method, which focuses on impurity removal, can provide a reference for the actual impurity removal in aluminum alloy smelting.

Influence of ultraviolet illumination on the corrosion behavior of 7A04 aluminum alloy in salt solutions with different pH values

This paper investigated the influence of ultraviolet (UV) illumination on the corrosion behavior of 7A04 aluminum alloy in 3.5% NaCl solutions with various pH values (pH=5.0, 7.0, and 10.0) using weight loss measurement, electrochemical methods, and surface analysis techniques. The research results indicated that the corrosion products of 7A04 alloy in salt solutions with different pH values all exhibited n-type semiconductor properties and could trigger the photovoltaic effect under UV illumination. Simultaneously, UV illumination reduced the compactness of the corrosion products, inhibited the enrichment of copper compounds (Cu2O), and promoted the generation of hydroxyl radicals in the solution. Therefore, UV illumination significantly accelerated the corrosion process of 7A04 alloy, with the overall acceleration effect ranking as follows: alkaline > neutral > acidic. In addition, the corrosion mechanism of 7A04 alloy in the test solutions with and without UV illumination was also discussed in this paper.

Experimental investigation of hybrid reinforced A356 aluminium alloy synthesised by stir casting technique

Abstract One of the most significant alloys to be employed in the automotive, aerospace, and military industries in recent years is A356 aluminium. Because of A356's excellent compatibility with other metals and nanoparticles, novel hybrid composites may be made using it. The characteristics of these hybrid composites are mostly the result of the additives' interaction with the A356 alloy's current elemental composition. Aluminium composites were synthesized through stir casting method by reinforcing 2%, and 4% SiC, 2% and 4 % Al2O3 and 0.5%, 1%, 1.5%, 2% and 2.5% SiC and Al2O3 both. The homogeneous distribution of SiC and Al2O3 microparticles in reinforced composite is revealed by scanning electron microscopy (SEM). The addition of SiC and Al2O3 reinforcements greatly improved the mechanical characteristics of the synthesised composites; for example, a composite with 4% SiC reinforcement reached its maximum hardness and maximum tensile strength of 165 HV and 257MPa respectively. Maximum elongation of 6.72 % was observed for 0.5% SiC and 0.5% Al2O3 reinforced composite. Minimum wear rate is observed for 4% SiC reinforced composite material. This study aims to identify gaps in the potential variations and compatibility of various additives with one another in order to create a brand-new hybrid reinforced alloy suitable for automotive braking system applications: brake rotors made of a disc or a brake pad, depending on the properties of the hybrid reinforced alloy that was made. Hence, the current work presented focuses on the preparation of hybrid reinforcement of A356 with silicon carbide and alumina powders.

Effect of process parameters on the mechanical properties of wires produced from A356 aluminum alloy chips by Continuous Friction Stir Extrusion: Experiments and numerical simulation

Recycling of metals is becoming crucial from an economic and environmental point of view. The solid-state recycling process Continuous Friction Stir Extrusion was used to produce wires out of A356-T6 chips. The mechanical properties of the produced wires were explored by varying the main process parameters. Characterization involved Vickers hardness tests, tensile tests, grain size measurements, and fracture surface analysis. It has been found that it is possible to achieve 77 % of the Ultimate Tensile Strength (UTS) and 92 % of Vickers hardness with respect to the as-fabricated A356 alloy. The average grain size increases with the tool rotational with values ranging from about 9 µm to about 11 µm. A 3D dedicated numerical model was used to predict the distributions and histories of primary field variables, and to calculate the Piwnik-Plata parameter, fostering a more in-depth understanding of the process mechanics. This allows for the precise prediction of unacceptable product quality of the bonding when the Plata and Piwnik parameters are low. Predicted temperature close to the rotating tool should reach 400 °C while the cochlea temperature should be below 100 °C for sound wires production thus avoiding early chip bonding and process failure.

Surface adhesion enhancement of anodized A5052 aluminum alloy with low-power atmospheric pressure plasma jets in order to recover wettability

Surface adhesion enhancement of anodized A5052 aluminum alloy with low-power atmospheric pressure plasma jets in order to recover wettability

Effect of two-step anodizing on corrosion and adhesion resistance of A5052 aluminum alloy

Effect of two-step anodizing on corrosion and adhesion resistance of A5052 aluminum alloy

Unveiling Thermal and Athermal Effects in Strain Hardening Removal of A6061 Aluminum Alloy

AbstractThis study explored the application of a high-density pulsed electric current (HDPEC) to mitigate strain hardening in a cold-rolled A6061 aluminum alloy while examining the simultaneous application of HDPEC with furnace heating to reveal the contributions of thermal and athermal effects. The results showed that significant strain-hardening relief was achieved through the HDPEC treatment, particularly at 300 A/mm² for 260 ms, resulting in a 23% reduction in strength and an 86% increase in ductility. Microstructural analysis revealed a shift to fine and equiaxed grains with reduced dislocation density, which was primarily attributed to thermal effects. HDPEC annealing exhibits superior efficiency compared to the conventional annealing treatment, offering cost and time advantages. In addition, this study validated the synergistic impact of HDPEC and furnace heating, with furnace heating supplementing energy requirements, facilitating practical HDPEC implementation. These findings suggest that the HDPEC method and the combined method with conventional heating are promising alternatives for strain-hardening alleviation in A6061 aluminum alloy manufacturing, supporting the development of an eco-friendly and efficient process. Graphical Abstract

Microstructure and fatigue properties of laser-MIG hybrid welding of medium-thickness 6005A aluminum alloy

Light alloys represented by aluminum alloys have a wide range of applications in railway transportation, the key load-bearing parts of high-speed train bodies are welded with a large number of medium-thickness plates, so the study of the welding performance of medium-thickness aluminum alloy plates is significant. In this study, laser-MIG hybrid welding technology is used to realize the single-layer, single-pass welding of 6005A aluminum alloy plate with a thickness of 10 mm. The grains in the weld zone (WZ) are coarsened by welding heat, and the average diameter is about 1.6 times that of the base metal (BM), while the average grain diameter in the heat-affected zone (HAZ) is similar to that of the BM. A softening phenomenon is observed in the welded joint, with a minimum hardness of 72.6 HV in the HAZ. TEM analysis shows that the softening phenomenon is caused by the coarsening of precipitate phases in the HAZ. In terms of tensile properties, the ultimate tensile strength (UTS) of the welded joint is approximately 237 MPa, which is 70.1 % of the BM. The fatigue strength (Nf = 2 × 106 cycles) of the welded joints is predicted to be 83 MPa, which is 64 % of the yield strength (YS), from the S-N curve obtained by fitting the tension–compression fatigue test data. Different morphologies of secondary phase particles are observed in the fatigue crack propagation zone, and their formation and effects on secondary crack are described. The fracture location indicates that softening behavior in the HAZ is the main factor influencing tensile performance, while defects in the WZ are the primary factors affecting fatigue fracture. The experimental results can enrich the tensile and compressive fatigue data of 6005A aluminum alloy.

Classification of surface roughness for milled A6061 aluminum alloy based on depth map models with convolutional neural networks

Classification of surface roughness for milled A6061 aluminum alloy based on depth map models with convolutional neural networks

Investigating the Influence of Low-Intensity Pulsed Magnetic Fields on Microstructure Evolution and Mechanical Properties of A356 Aluminum Alloy

Investigating the Influence of Low-Intensity Pulsed Magnetic Fields on Microstructure Evolution and Mechanical Properties of A356 Aluminum Alloy