Wrought Aluminum Alloys Research Articles

Rendering wrought aluminium alloys castable by means of minimum composition adjustments

Wrought alloys have low fluidity and are prone to hot tearing, which make them difficult to cast. The presence of eutectic-forming elements in the alloy composition lessens these effects. For this reason, the constituents of casting alloys tend to include a eutectic portion. Typically, silicon is added to aluminium alloys to provide casting ability by forming the aluminium–silicon eutectic. However, the presence of silicon in aluminium alloys is associated with a number of issues that do not allow these alloys to reach their full potential. In this publication we report results of our investigation of three alternative eutectics: Al–6.1Ni, Al–1.8Fe, and Al–1.75Fe–1.25Ni. Our results indicate that these eutectics have satisfactory fluidity and resistance to hot tearing and higher strength than the aluminium–silicon eutectic. We also found that introducing these eutectic compositions into 7075 wrought alloy results in a castable composition with yield strength comparable to that of the wrought alloy.

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

Effects of Process Conditions on the Mechanical Behavior of Aluminium Wrought Alloy EN AW-2219 (AlCu6Mn) Additively Manufactured by Laser Beam Melting in Powder Bed

Additive manufacturing is especially suitable for complex-shaped 3D parts with integrated and optimized functionality realized by filigree geometries. Such designs benefit from low safety factors in mechanical layout. This demands ductile materials that reduce stress peaks by predictable plastic deformation instead of failure. Al–Cu wrought alloys are established materials meeting this requirement. Additionally, they provide high specific strengths. As the designation “Wrought Alloys” implies, they are intended for manufacturing by hot or cold working. When cast or welded, they are prone to solidification cracks. Al–Si fillers can alleviate this, but impair ductility. Being closely related to welding, Laser Beam Melting in Powder Bed (LBM) of Al–Cu wrought alloys like EN AW-2219 can be considered challenging. In LBM of aluminium alloys, only easily-weldable Al–Si casting alloys have succeeded commercially today. This article discusses the influences of boundary conditions during LBM of EN AW-2219 on sample porosity and tensile test results, supported by metallographic microsections and fractography. Load direction was varied relative to LBM build-up direction. T6 heat treatment was applied to half of the samples. Pronounced anisotropy was observed. Remarkably, elongation at break of T6 specimens loaded along the build-up direction exceeded the values from literature for conventionally manufactured EN AW-2219 by a factor of two.

Electron beam welding of aluminum alloy casting and wrought aluminum alloy

Electron beam welding of aluminum alloy casting and wrought aluminum alloy

Effect of Particle Size on Mechanical Properties of Al-RMp Metal Matrix Composites

Particle reinforced aluminum matrix composites (AMC) have invoked a potent interest in recent times for applications in aerospace industries. Al- MMCs have improved mechanical, tribological, strength to weight ratio when compare to monolithic metals and alloys. Red mud (RMp), a residue of a Bayer process was selected as reinforcement with three different grain sizes of 90,120,180 microns and wrought aluminum alloy 8011 as a matrix material. Normal stir casting route is adopted to cast the composites by varying the wt.% of the RMp from to 4% to 20% in increment of 4%. Prepared composites are then tested for mechanical properties as per the ASTM standards. From the obtained results it is observed that 24.45% increase in tensile strength in Al-14wt% RMp90 composition and good hardness and compressive strength in Al-20wt% RMp180 composition is obtained.

Comparison of the Effects of Surface Roughness of Wrought Aluminium Alloys on the Surface of Steel

The effect of roughness of wrought aluminium alloys on the surface of steel is investigated. Roughness average (Ra) was a fixed polishing at 14 ± 0.05 μm. Also was using a pin–on disc, made of AISI 1045 steel and Ra=0.15 ± 0.05 μm, Hv=312 ± 20 kg/mm2. All tests were carried out as per ASTM G-99 standard. The angular speed of the disc was a fixed 200 rpm and a load range of (5, 10, 15) N, and relative humidity 65%. The microstructure for samples and worn surfaces were analyzed and characterized using X-ray diffraction the residual voltage (XRD), energy dispersive spectroscopy (EDS), scanning of electron microscopy (SEM) and atomic force microscopy (AFM), respectively. It was noticed that the dry sliding wear of aluminium alloys against a steel counterface resulted in severe wear for all alloys. At a load of 10 and 15 N, performs a better effect of wear resistance of A 6092 alloy and was wear reduction is 18% comparison with A5056 and A 3003 alloys and reduce friction. However, at a heavy load of 15 N, only the pattern can effectively reduce friction. The maximum reduction rate of the average wear depth is 20% of A 6092 alloy while a reduce 29% and 40% in A5056 and A3003 alloys respectively. However, there was correlation between roughness and wear rate. In all cases, a mechanically mixed layer was formed. Deformation below worn surface and wear resistance is discussed.

Effect of Different Cooling Rates Condition on Thermal Profile and Microstructure of Aluminium 6061

Thermal analysis and microstructure characterization provide information regarding material thermal profiles and microstructure formation. Wrought aluminium alloys offer significant advantages in terms of higher ultimate tensile strength (UTS) and yield strength but relatively poor fluidity properties. The objective of this experiment presented in this paper was to understand the relationship between solidification rate, metallurgical behaviour, and fraction phase growth of wrought aluminium 6061. This information was crucial and important to the foundry industry to understand the material behaviour that will help to cast wrought aluminium 6061. Thermal analysis and microstructure of wrought aluminium 6061 on different cooling conditions are present in this paper. In this work, Aluminium 6061 heated and melted in a graphite crucible at a temperature of 800°C. Two thermocouples located at the centre and 20 mm from the graphite crucible wall. Slow cooling rate condition experiment rig was developed by placing graphite crucible into a chamber with kaowool insulation. Normal cooling rate condition was developed by allowing the molten solidify at room temperature. Fast cooling rate condition was prepared by applying a forced airflow over the graphite crucible. The slow, normal, and high cooling rates were calculated at 0.03°C/s, 0.2°C/s and 0.3°C/s respectively. Cooling curve analysis was performed to predict various areas of solidification phase and fraction solid. In Addition, the microstructure formation was observed, recorded, and compared between different cooling conditions. The results show slow cooling rate condition formation of eutectic and solidus temperatures occurred far from liquidus temperature. The eutectic and solidus temperature was increased with the increment of the cooling rate. Furthermore, the DCP temperature of slow cooling rate condition at 638.3°C was the lowest while gives wider temperature range corresponding to the fraction solid percentage increment. Meanwhile, an increase in cooling rate refined the microstructure, improved the grain circularity and at the same time reduced the aspect ratio.

Effect of pre-homogenization deformation treatment on the workability and mechanical properties of AlMg5Si2Mn alloy

This study evaluated the effect of a novel treatment method on the potential application of AlMg5Si2Mn die casting alloy as a substitute for wrought aluminum alloy in products. The proposed pre-homogenization deformation treatment was intended to increase the hot workability of the AlMg5Si2Mn alloy, which is typically not malleable due to the presence of interconnected brittle phases. By disintegrating interconnected eutectic Mg2Si phases into fragmented particles, the slight cold rolling before homogenization significantly enhanced hot rolling workability. Rolled sheets were successfully fabricated by hot and subsequent cold rolling, and the sheets exhibited enhanced mechanical properties compared to cast samples.

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Heat Transfer Modeling and Thermal History Analysis

Friction stir welding (FSW) is a technique that can be used for materials joining and local microstructural refinement. Owing to the solid-state character of the process, FSW has significant advantages over traditional fusion welding, including reduced part distortion and overheating. In this study, a novel heat transfer model was developed to predict weld temperature distributions and quantify peak temperatures under various combinations of processing parameters for different wrought and cast Al alloys. Specifically, an analytical analysis was first developed to characterize and predict heat generation rate within the weld nugget, and then a two-dimensional (2D) numerical simulation was performed to evaluate the temperature distribution in the weld cross-section and top-view planes. A further three-dimensional (3D) simulation was developed based on the heat generation analysis. The model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for all studied materials and conditions.

Modeling of path-dependent multi-axial fatigue damage in aluminum alloys

This paper presents a comprehensive investigation into non-proportional loading induced multi-axial fatigue damage in aluminum alloys using a recently developed multi-axial fatigue damage parameter. The moment of load path (MLP) based fatigue damage parameter is formulated in a form of an equivalent stress or strain range that measures both the extent of load-path deviation from proportionality within a fatigue cycle and material sensitivity to load-path non-proportionality. The use of such a fatigue damage parameter for correlating a large amount of test data is given in a recent publication by Mei and Dong (2016) for structural steels that were shown very sensitive to non-proportional loading. This study examines another class of materials such as various types of wrought aluminum alloys (including 2000, 5000, 6000 and 7000 series) that are typically viewed as being less sensitive to non-proportional loading. A generalized procedure for extracting material sensitivity parameter from stress-life or strain-life test data under simple multi-axial loading conditions is first presented. After obtaining material sensitivity parameter for each of the wrought aluminum alloys examined in this study, it is found that material sensitivity parameter can be related to material ductility (in terms of percentage of elongation from tensile tests) in an approximately linear manner in both low-cycle and high cycle regimes. An excellent agreement (mostly within a factor of 3) is achieved between model-estimated fatigue lives and test lives for all materials under various non-proportional multi-axial loading conditions considered in this study.

Application of Vertical-Type High-Speed Twin-Roll Casting for Up-Grade Recycling and Clad Sheets Fabrication of Aluminum Alloys

A horizontal-type twin roll casting method has been popular for producing aluminum alloy strips, however, it is characterized by a relatively low productivity (1~6 m/min). In contrast, a vertical-type high-speed twin-roll casting method possesses an extremely high productivity (60~120 m/min (1~2 m/s)) and an excellent heat extraction ability. The rapid cooling effect provided significant microstructure refinement and mechanical properties improvement in various kinds of cast aluminum alloy products. Not only “product to product recycling” but also “up-grade recycling” can be achieved by making good use of these merits. Two examples of application showing the potential of vertical-type high-speed twin roll casting method are presented. (1) Several kinds of Al-Si base alloy were cast into the strips. Not only strength and toughness but also formability was increased in the twin roll cast products. In particular, great improvement in deformability shows the potential of the twin-roll cast aluminum alloy products as substitutes for some wrought aluminum alloy products. (2) The vertical-type tandem twin-roll caster was able to fabricate a clad strip by single step. The A4045/A3003/A4045 aluminum alloy clad sheets produced by the twin-roll casting showed better mechanical properties than the conventional hot-roll bonded clad sheets.

Determination of Metal/Die Interfacial Heat Transfer Coefficients in Squeeze Casting of Wrought Aluminum Alloy 7075 With Variations in Section Thicknesses and Applied Pressures

Squeeze casting of wrought aluminum 7075 was carried out on a 75-ton hydraulic press. Metal/die interface heat transfer phenomena in squeeze casting of the alloy were investigated. To facilitate experimental measurements, a five-step casting mold was designed for the experiments. The five-step casting consisted of five different section thicknesses of 2, 4, 8, 12, and 20 mm. Squeeze casing experiments were performed under the applied hydraulic pressures of 30, 60, and 90 MPa. Temperatures were measured at the casting surface and at various specific locations inside the die. At each step, thermocouples were placed at 2, 4, and 6 mm away from the inside die face. Based on the measured temperature results, the interfacial heat transfer coefficients (IHTCs) and heat fluxes were determined by solving the one-dimensional transient heat conduction equation with the inverse method. With increasing the casting section thicknesses from 2 to 20 mm, the peak IHTC values varied from 1683.46 W/m2 K to 9473.23 W/m2 K, 2174.78 W/m2 K to 13,494.05 W/m2 K, and 3873.45 W/m2 K to 15,483.01 W/m2 K for the applied hydraulic pressures of 30, 60, and 90 MPa, respectively.

A New Al-Zr-Ti Master Alloy for Ultrasonic Grain Refinement of Wrought and Foundry Aluminum Alloys

The authors wish to acknowledge financial support from the ExoMet Project, which is co-funded by the European Commission in the 7th Framework Programme (contract FP7-NMP3-LA-2012-280421), by the European Space Agency and by the individual partner organisations.

Investigation on Tensile and Impact Behavior of Aluminum Base Silicon Carbide Metal Matrix Composites

Objectives: The scope of this work was to: 1. to fabricate Silicon Carbide (SiC) particle Metal Matrix Composites (MMC) by vortex method; 2. to investigate the effect of SiC particles on the tensile and impact behavior of SiC particle reinforced 6061 aluminum alloy composites. Recently, the material technology has seen many contemporary developments in the field of fabricating new materials which reinstates the current materials for different applications. Amidst these, the composite materials have an important aspect which is a combination of different materials possessing various physical and chemical properties. Methods: This Aluminum base metal Matrix Composite (AMC) has been manufactured by wrought aluminum alloy by varying the weight fractions of silicon carbide to compose five distinct forms of composites. Stir – casting has been chosen as the manufacturing technique, in this study. Findings: The manufactured composites were tested to determine their tensile and impact properties and the result proves that the sample with higher percentage of silicon carbide has better mechanical properties, comparably. Applications: This study essentially focuses on establishing AMC as they find applications on aerospace and automotive industries because of their admirable properties compared with the unreinforced alloysKeywords: Aluminum 6061, Mechanical Properties, Metal Matrix Composite, Silicon Carbide, Stir Casting

Effect of Globular Microstructure on Cavitation Erosion Resistance of Aluminium Alloys

In this paper the effect of globular microstructure on the cavitation erosion resistance was assessed and compared to that of conventional dendritic one. Three different wrought aluminum alloys in as-cast conditions were investigated. The samples were completely characterized by metallographic analyses and microhardness measurements. Cavitation erosion tests were performed according to ASTM G 32 standard. The volume loss was evaluated during the test by periodical interruptions. It was identified the damaging mechanism in case of both dendritic and semisolid microstructure. It was also found that the globular microstructure increases the cavitation erosion resistance only for one of the studied alloys.

Advances and Potentials in Friction Stir Welding of Aluminum Alloys

Within the last decade, Friction Stir Welding (FSW) has increasingly been gaining relevance for joining nonferrous metals, especially aluminum alloys. Possible applications range from the aerospace and automotive sector up to manufacturing electrical components. Compared to conventional fusion welding processes, FSW offers numerous advantages, as it for example does not require shielding gas or filler material. However, FSW is still not applied or taken into account during the product development process in proportion to its potential. This is mainly caused by the lack of data in order to evaluate the process economically and differentiate it to other processes like arc and laser welding, also regarding technological factors. Therefore, this investigation focusses on the possibilities and limits when joining wrought and cast aluminum alloys, like EN AW-6082 T6, EN AW-7075 T651 and AlSi11Mg0,3, respectively, by FSW compared to MIG. The weld quality of the samples is characterized by tensile testing, hardness measurements and microstructure analysis. Furthermore, an approach to reduce the process forces by using FSW tools with reduced diameters and respectively adjusted process parameters is presented.

Microstructure and Rheological Properties of Semi-Solid 7075 Slurries Using SEED Rheocasting Process

The SEED rheocasting process was used to produce semisolid slurries of high strength 7075 aluminum wrought alloys. The effects of the SEED processing parameters on the microstructure of semisolid slurries were studied. The impact of grain refinement on the grain morphology and size was investigated. The rheological properties of semisolid 7075 alloys were characterized at different solid fractions using a parallel plate compression viscometer. Results indicated that the grain refinement could greatly improve the globularity of α-Al grains and rheoformability. The relationships between viscosity and shear rate at different solid fractions in the transient state for both unrefined and refined semisolid slurries were evaluated and discussed.

Wrought Al - Cast Al compound casting based on zincate treatment for aluminum wrought alloy inserts

The surface properties of solid inserts are critical to the development of a reaction zone in compound castings. In contrast to prior works (based on Al99.5) the goal of this paper is to apply the zincate treatment to different aluminum wrought alloys. This enables the possibility to create compound structures with enhanced mechanical properties. During zincate treatment the aluminum oxide layers are dissolved and a thin layer of zinc (<500nm) prevents reoxidation. Coating parameters are optimized especially for compound castings: maximum coverage of the surface and high coating adhesion implemented by double zincate treatment. The pretreated inserts are embedded in an aluminum component by high pressure die casting. A sound metallic bonding between both aluminum alloys develops due to diffusion and reaction zones. Mechanical tests confirm a sound metallic bonding. Depending on the integrated wrought alloy enhanced mechanical properties of the compound structure can be achieved. Microprobe and fracture analysis provide detailed information about the interface properties of the compound structure, which can be enhanced by thermal treatment.

Mechanical Properties Evaluation of Zr Addition in L12-Al3(Sc1−x Zr x ) Using First-Principles Calculation

L12-Al3(Sc1−x Zr x ) can be used as a grain refiner and recrystallization inhibitor in forming and heat-treatment of wrought aluminum alloy. In this work, the mechanical properties of L12-Al3(Sc1−x Zr x ) (0 < x< 0.5) have been systematically evaluated using first principles calculations. The optimized structural parameters obtained through the virtual crystal approximation were in good agreement with available experimental and calculated data. The computed bulk modulus of L12-Al3(Sc1−x Zr x ) increased while the shear modulus and Young’s modulus decreased with increasing Zr addition. The ductility of L12-Al3(Sc1−x Zr x ) estimated by Pugh empirical criterion and Cauchy pressure were improved with Zr addition. The calculated ideal strength of L12-Al3(Sc1−x Zr x ) along the [001], [110] and \( \{ 111\} [1\bar{1}0] \) directions increased linearly with Zr additions. The addition of Zr gave great improvements in the ideal strength along the [110] direction and the ductility in the [001] direction, respectively. The calculated electronic density of states and the charge density distribution revealed that the valence electron increased with Zr addition and hence strengthened the p–d covalent bonding and d–d bonding, resulting in the improvements in ideal strength and ductility. The evaluation data would be useful in materials design and process optimization for Al alloys in forming and heat treatment.

Microstructure and properties of rheo-diecasting wrought aluminum alloy with Sc additions

In this paper semisolid slurry of Al-6.3Zn-1.9Mg-1.8Cu-0.15Zr alloy with different levels of Sc was prepared, and the effect of Sc content on the morphology of microstructure and mechanical properties of the rheo-diecasting samples was investigated. The results indicate that the excellent semisolid slurry of the wrought Al alloy could be obtained with the addition of 0.22%Sc. Sc additions not only influenced the morphology of the primary α-Al particles in the slurry, but also promoted the formation of fine α-Al globules in the solidification process of the remaining liquid, which contributed to the considerable improvement in tensile strength and elongation. The tensile strength and elongation of the rheo-diecasting samples with 0.45%Sc after T6 heat treatment increased by 82% and 147% respectively compared to the die-casting samples of the base alloy.