Aluminum Alloy AA Research Articles

Optimizing joint structure and performance in friction spot joining of aluminum alloy AA6061 and poly-ether-ether-ketone (PEEK)

This study investigated the challenge of joining poly-ether-ether-ketone (PEEK) to aluminum alloy AA6061 through friction spot joining (FSpJ), by examining the impact of surface treatment of AA6061 sheets and analyzing various process parameters' effects on joint interface morphology, tensile-shear strength, and failure. Results indicated a peak interface temperature may reach 400 °C during FSpJ, with a 0.5–0.9 mm molten PEEK layer containing sealed bubbles. Notably, Boehmite treatment significantly improved joint strength, although the primary failure occurred in the PEEK base material. An optimization through response surface method (RSM) analysis identified plunging depth as the most influential factor in joint strength, and a peak load of 4576 N with an optimized combination of pin rotation speed, plunging depth, and dwell time was achieved. Using optimized process parameters, strong PEEK-AA6061 joints can be formed, and the approach is extendable to joining other metallic and polymeric materials.

A Novel Strategy for Realizing Reliable Welding of Aluminum-Steel

This study proposed a novel welding strategy called active-expulsion-assisted resistance spot welding (RSW), which was used to address the limitations of RSW of aluminum to steel. The method primarily comprised an intentionally set expulsion stage and a locking stage. In the expulsion stage, a short-duration expulsion pulse with a relatively large welding current was applied to melt the aluminum and induce liquid aluminum expulsion. Then, in the locking stage, a welding current pulse was used to join the locking sheet and the steel workpiece. A combination of quenched and partitioned 1180 steel and AA6016 aluminum alloy with and without adhesive was used for welding. Experimental results showed that the expulsion pulse efficiently removed the aluminum alloy in the weld, creating the conditions for fundamentally avoiding the formation of brittle intermetallic compounds in the nugget during the subsequent welding stage. After the welding pulse, a strong joint was generated between the locking sheet and the steel, thus realizing a firm connection for the combination of welding and riveting between an aluminum alloy and steel substrate.

Structural Features and Morphology of Surface Layers of AA2024 and AA5056 Aluminum Alloys During Plasma Cutting

Structural Features and Morphology of Surface Layers of AA2024 and AA5056 Aluminum Alloys During Plasma Cutting

Numerical and Experimental Analysis of the Forging of a Bimetallic Crosshead

Abstract The automobile sector has been making increasing efforts to reduce the weight of automobiles, aiming at mitigating pollutant gas emissions. The use of innovative concepts, such as bimetallic components, has become attractive because it makes it possible to increase the strength-to-weight ratio of the components. In this study, the hot forging of a bimetallic crosshead is investigated. In the process, a billet with a cylindrical core of the magnesium alloy AZ61 is enclosed with a hollow cylinder of the aluminum alloy AA 6351 and forged at 400°C. The objective is to reconcile the low density of Mg alloys with the high corrosion resistance of Al alloys. In parallel, a finite element analysis of the process was carried out.

Influence of Clad Layer Thickness of Aluminium Alloy by Friction Surface Cladding Process

Friction Surface Cladding (FSC) is a process that enables the deposition of clad material on a substrate through a hollow rotating tool to create thin clad layers at sufficiently high temperatures. Heat is produced during the cladding process by friction at the tool-clad layer and the substrate. This study focus on the influence of clad layer thickness of aluminium alloy AA2024 at the control process temperature around 300℃ to 350℃. The material used is AA2024-T4 for the clad layer and AA2024-T351 for the substrate. A thermal model is built using COMSOL Multiphysics 6.0 and Heat Transfer in Solid (ht) with time-dependent study is used to study the heat transformation as well as optimize the rotational speed at different clad layer thicknesses. The major finding in this study indicates that the heat generated is proportional to the clad layer thickness. The highest heat transformation can be seen at the cladding region between the cladding rod and the substrate and the temperature reaches a maximum of 333.95℃.

Effect of TiC nano-treating on the fluidity and solidification behavior of aluminum alloy 6063

Wrought aluminum alloy AA 6063 is known for its favorable mechanical properties, corrosion resistance, and weldability in high-performance applications. Nonetheless, its limited fluidity hinders the cost-effective production of intricate structures through economical casting processes. To address this, a small fraction of TiC nanoparticles were dispersed into the AA 6063 melt to enhance its fluidity, eliminate hot cracking, and improve casting surface quality. Further investigation indicates that nanoparticles contribute to gradual latent heat release, grain growth restriction, and improved molten alloy wettability. The results demonstrate the potential of the emerging nano-treating technology in making traditionally difficult-to-cast alloys viable for low-cost casting operations to deliver products with enhanced high performance for numerous applications.

Development of polyamide 6‐graphene oxide nanocomposite and direct‐joining with aluminum alloy for lightweight engineering applications

AbstractLightweight polyamide composites and structures have been widely studied and employed in several industrial sectors. In this study, the development of a nanocomposite of polyamide 6 and graphene oxide (PA6‐GO) by melt‐compounding and the joining with aluminum alloy AA6061 through direct‐adhesion injection overmolding are addressed. PA6‐GO nanocomposite exhibited well‐dispersed thin (300 nm) GO platelets distributed within the PA6 matrix, which resulted in an increase of 21% in the tensile modulus and 16% in the yield stress for a filler loading of 0.5 wt%. PA6‐GO/AA6061 hybrid joints showed good mechanical anchorage through the complete filling of the polymer into micro‐scale grooves designed onto the metal surface, which ensured outstanding shear strength of 7.1 ± 1.0 MPa, comparable to other polyamide‐metal hybrid joints reported in the literature. This indicates that the processing routes and materials developed are promising for lightweight engineering applications.Highlights A PA6‐GO nanocomposite with enhanced tensile properties was developed. A joint of PA6‐GO and AA6061 with outstanding shear strength was obtained. Fast and efficient melt‐processing routes were employed. These materials are promising for lightweight engineering applications.

Performance Assessment of Different Pin Profiles in Friction Stir Welding of AA2014 Aluminum Alloy: A Microstructural and Mechanical Analysis

Performance Assessment of Different Pin Profiles in Friction Stir Welding of AA2014 Aluminum Alloy: A Microstructural and Mechanical Analysis

Gaussian process regression-driven deep drawing blank design method

This research introduces a machine learning (ML)-based methodology for the optimal blank design of components manufactured through the deep drawing process, considering the interplay among material, process, and geometric parameters. The proposed blank design mapping function (BDMF) leverages a Gaussian process regression (GPR) ML model in conjunction with a radial basis function (RBF) kernel. This combination allows for correlating predictions with their standard deviations, capturing the estimations' quality effectively. The GPR model was trained using the results from a three-dimensional adaptive mesh-based finite element analysis (FEA) model, characterized by a fixed node count of 23 input parameters, an explicit solution scheme, and an average computational time of 270 s. Laboratory-scale experiments on an R47.5 mm flanged cup constructed from AISI-304 steel and AA5754 aluminum alloy served to validate the FEA models and the proposed BDMF. The comparison between experimental outcomes and FEA results revealed maximum deviations of 13.3 % in the drawing force and 0.35 % for the earing profile over a 90° segment. The comparison between experimental data and BDMF predictions for the sheet metal blank indicated average deviations of 0.015 mm (or 1.3 %) in estimating thickness and 0.12 mm (or 0.25 %) in predicting the outer radius. Application of the BDMF to four additional flanged geometries with varying shapes demonstrated its reliability and generality; the maximum and average deviations for the earing profile were 4.3 % and 3.1 %, respectively, and for post-forming sheet thickness, they were 6.7 % and 3.1 %, respectively.

Investigation on shear and fatigue performance of CFRP/aluminum alloy single-lap adhesive joint

The size parameter is quite significant for the performance of adhesive joint. In order to investigate the effect of size parameters on the mechanical property and failure behavior of CFRP/aluminum alloy single-lap adhesive joint, T300 CFRP laminate and AA5182 aluminum alloy sheet were bonded by Sika Power 497 structural adhesive under different size parameters. The quasi-static shear test and fatigue test were implemented, and the failure behavior and failure mechanism were analyzed. Results showed that the increase of aluminum alloy sheet thickness or bonding area length could effectively improve the bonding strength of adhesive joint, when the strength of the aluminum alloy sheet or the adhesive layer was insufficient. The shear failure modes of adhesive joint mainly included adhesive failure, base material failure and mixed failure. The fatigue failure modes of adhesive joint were mainly adhesive cohesion failure and adhesive adhesion failure. At low stress levels, the aluminum alloy sheet might fracture. In addition, this work can provide a scientific guidance for the engineering application of adhesive bonding technology.

Characterization of friction stir-based linear continuous joining of aluminium alloy to structural polymer

Dissimilar continuous joining of lightweight metal alloys to structural polymer is a major manufacturing challenge, demanding feasible and reliable solutions. Through-slot extrusion joining (TSEJ) is a friction stir-based processing technique investigated in the manufacturing of continuous linear joints between aluminium alloy AA5754 overlapping structural polymer polyether ether ketone (PEEK). An intermediate rigid and thin titanium extrusion die protects the polymer locally from thermal degradation and promotes the formation of a continuous double hook-like feature of extruded aluminium into the polymer component along the joint path. The structure of the joint provides macro-mechanical interlocking between the joined components. A set of four tools, and other key process parameters, were investigated for process stability, tensile-shear strength, and microstructure. The best TSEJ condition is chosen for microstructural analysis via optical microscopy and scanning electron microscopy. Three distinct failure modes were identified. The best condition provided an average tensile-shear load of 110 kN/m. The tool position with bias toward the flow side of the extrusion slot shows to improve the strength of joints. The microstructural analysis along the interface of AA5754 to PEEK exhibits micro-mechanical interlocking, intercalated layers of these materials and adhesion as joining mechanisms.

A Study of the Friction Stir Lap Welding of AA5052 and Polypropylene.

Friction stir lap welding (FSLW) remains a pioneering technique for creating hybrid joints between AA5052 aluminium alloy and polypropylene (PP), particularly with the metal-on-top configuration. Building upon previous research, this study introduces a tapered fluted pin tool design and investigates its effectiveness in the welding process. Our results, supported by ANOVA, chemical, and microstructural analyses, reiterate that the optimal welding parameters stand at a rotational speed of 1400 RPM and a traverse speed of 20 mm/min. This combination produces a joint tensile strength of 3.8 MPa, signifying 16.54% of the weaker material's inherent strength. Microstructural evaluations revealed a unique composite of aluminium chips intermeshed with PP, strengthened further by aluminium hooks. Crucially, mechanical interlocking plays a predominant role over chemical bonding in achieving this joint strength. The study underscores the absence of significant C-O-Al bonds, hinting at the PP degradation without the thermo-oxidation process. Additionally, joint strength was found to inversely correlate with the interaction layer's thickness. The findings fortify the promise of FSLW with the novel fluted pin design for enhancing joints between AA5052 and PP, emphasising the potential of mechanical interlocking as a principal factor in achieving high-quality welds.

Friction stir welding of dissimilar AA7050 and AA5083 aluminium alloys: Microstructural and mechanical characterization

In this study, dissimilar aluminium alloys, AA7050-T7651 and AA5083-H111, with 5 mm thickness were friction stir butt welded and the microstructural and mechanical properties of the joints are investigated. The experiments were carried out at tool rotational speeds of 800, 1000 and 1200 rpm while keeping the tool traverse speed, axial force and tool tilt angle, respectively, at constant values of 30 mm/min, 3.5 kN and 1.5°. A tool axis offset of 0.25 mm towards the 7xxx alloy side that fixed by a detailed preliminary study was used in all the trials. All the fabricated joints were externally defect-free and the fractured tensile specimens showed that the joints have fractured in the thermo-mechanically affected zone (TMAZ) at the AA5083-H111 alloy side. The highest ultimate tensile strength of 294 MPa (96% joint efficiency) was observed for the joint fabricated at tool rotation speed of 1000 rpm. The location of fracture together with the microstructure observation at the joint zone showed that the coarsening of grains and loss of cold work are the causes of fracture of the tensile specimen at the TMAZ of the 5083-alloy side. In addition, significant grain coarsening and dissolution of precipitates are observed at the heat-affected zone and TMAZ at the 7050-alloy side at tool rotational speeds of 1000 rpm and 1200 rpm. The study testified that the tool rotational speed has a significant influence on the microstructure and tensile properties of the dissimilar joints.

Enhancing the ultrasonic plastic welding strength of Al/CFRTP joint via coated metal surface and structured composite surface

Ultrasonic plastic welding (UPW) is a promising technology for joining metal to carbon fiber reinforced thermoplastic composite (CFRTP) but shows poor joint strength in the existing studies. This work conducts UPW of AA6061 aluminum alloy to carbon fiber reinforced PA66 (CF/PA66) by employing a polymer coating as an interlayer. Simple metal surface grinding and silane coupling agent (SCA) treatment are used to strengthen the bonding of the metal/coating interface. Structured CF/PA66 surface fabricated by ultrasonic embossing acts as energy directors to improve the bonding strength of the coating/plastic interface. The results show that relatively high tensile-shear strength (about 31.0 MPa) can be obtained. Micro-mechanical interlocking and chemical bonding (Al-O-C and Al-O-Si bonds) are considered as the bonding mechanism of the metal/coating interface.

Effect of process parameters on friction stir welding of aluminium alloy AA6082–T6 with an interlayer using response surface methodology

In the present study, the effects of variation of process parameters on the mechanical properties of friction stir welded A6082–T6 aluminium alloy joints with Zinc (Zn) interlayer are experimentally investigated. Four process parameters, viz. rotational speed, welding speed, interlayer thickness and tool pin diameter are selected to fabricate the Friction Stir Welding (FSW) joints. After filling the Zn particles into the gap maintained between the plates, FSW is performed using different process parameters. Thereafter, tensile and impact strength tests are performed to evaluate the performance of the joints. It is analyzed that the tensile and impact strength of the joints vary from 121 to 197 MPa and 6 to 17 J, respectively. Subsequently, mathematical models are developed using Response Surface Methodology (RSM) to predict the effect of FSW process parameters on the tensile and impact strength of joints. Analysis of Variance (ANOVA) is used to check the level and degree of direct effect of process variables on the tensile and impact strength of the joints. It is observed from the results that tool rotational speed is the most influential process parameter, which enhances the mechanical properties of FSW joints, whereas an increase in welding speed reduces the mechanical properties of the joints.

Evaluation of strength and electrical conductivity of copper clad-AA6063 bimetallic composite wire after annealing treatment

This study investigates the manufacturing of copper-AA6063 aluminum alloy composite wire and the effect of microstructural changes and metal-metal interface after annealing at 300 °C at different times on the strength and electrical conductivity. For fabrication of the composite wire, first AA6063 aluminum alloy wire was inserted inside an OFHC copper tube with a diameter of 6 mm. Afterward, a composite wire was produced using a cold drawing process in thirteen steps to a diameter of 1.5 mm. The tensile and microhardness tests used for evaluation of the composite wire's mechanical properties. Also, the light and scanning electron microscopes (SEM) used for microstructural characterization. The results showed that forming a region with a strain gradient at interface has a determinative effect on the strength and ductility of composite wire. The composite wire without annealing showed the highest strength, 278 ± 7 MPa. The annealing treatment result in strength reduction and negligible change in the electrical conductivity. The composite wire after annealing treatment for 30 and 60 min showed the highest electrical conductivity, 83 ± 1%IACS, and the highest elongation, 45 ± 4%, respectively.

Influence of a Stationary Shoulder Friction Stir Welding Tool on the Mechanical and Corrosion Properties of AA2024 Aluminum Alloy Joints at Different Parameter Values

Influence of a Stationary Shoulder Friction Stir Welding Tool on the Mechanical and Corrosion Properties of AA2024 Aluminum Alloy Joints at Different Parameter Values

Influence of dissimilar plate thickness on temperature during friction stir welding between AA5083 and AA6061 aluminium alloy grades

This paper investigates the influence of dissimilar plate thickness on the temperature profile of AA5083 and AA6061 aluminium alloy. Plates of dissimilar aluminium alloy grades are welded in a butt joint configuration by using a milling machine and a custom FSW tool made of H13 tool. Datalogger and type K thermocouples embedded in the workpieces at different distances from the weld line are used to collect the temperature data during the experiment. One thermocouple is placed at each side of the advancing side and retreating side at equally distance from the center line except for Joint 1, 2 and 3. The results show the range of temperature measurement during the experiment is between 300°C and 600°C. FSW process between similar plate thickness produces the highest value of peak temperature and better surface appearance than dissimilar plate thickness. The thermocouples located near the weld line contributed the higher temperature since the heat source comes from the rotating tool. Besides, higher temperatures were recorded at 5 mm thickness of AA6061 aluminium alloy plate located on the advancing side than the retreating side.

Characterization of pulsed-tungsten inert gas (PTIG) welding on AA5754-H111 alloy: mechanical properties and microstructural analysis

Abstract Aluminium and its alloys were widely used in engineering because they are lightweight, strong, and resistant to corrosion. However, using standard arc welding techniques can be difficult when dealing with such materials. Pulsed-Tungsten Inert Gas (PTIG) welding is being researched as a potential solution to this problem. This study is the first to investigate the use of the straightforward and intuitive PTIG technique on the ubiquitous AA5754 wrought aluminium alloy. Welded samples were supplied for examination of mechanical parameters such as surface hardness and strength under impact and tensile loading. The results of a statistical analysis of the mechanical characterization of a PTIG-welded permanent joint fabricated from AA5754 aluminium alloy were presented and discussed. The heat-affected zone (HAZ) on the AA5754 retracting side of the weld had a hardness of 50–70 Hv0.5, while the HAZ on the AA5756 side had a hardness of 90–100 Hv0.5, as measured by testing on the perfect weld specimen. Samples taken from different parts of the weldment all showed that the HAZ is the softest and weakest. The shattered surface of the welded sample consisted of flat facets and quasi-cleavage patterns, as revealed by scanning electron microscopy. Analysis of the HAZ microstructure revealed widespread dissolution of Mg2Si precipitates in the AA5754-H111.

Electrochemical corrosion of aluminium alloy AA1050, processed by accumulative roll bonding

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