Aluminum Components Research Articles

Microstructure and Fatigue Behavior of High-Performance Aluminum Alloy Al2024 Produced by Laser Powder Bed Fusion

Aluminum-based alloys are widely used in high-performance structural applications. Therefore, the opportunity to fabricate aluminum components using Laser Powder Bed Fusion (L-PBF) is a matter of great interest. In particular, the Al2024 alloy is extensively used for conventional part production but its processability by L-PBF remains a challenge because of its hot cracking sensitivity upon solidification. The new Reactive Additive Manufacturing (RAM) technology by Elementum 3D enables the production of innovative powders characterized by metal matrix and nanoceramic particles that can be processed using L-PBF. The ceramic nanoparticles of 2 % by weight improves properties and prevents Al2024-RAM2 alloy cracking during solidification. The present study investigates the fatigue performance of Al2024-RAM2 alloy manufactured by L-PBF using an SLM 280 HL equipment with a nominal layer thickness of 60 µm. A set of miniature vertical fatigue specimens were manufactured then underwent to a heat treatment T6. The specimens were tested in the as-built state (i.e., without any surface post-processing) under cyclic plane bending at a load ratio R = 0 at a frequency of 25 Hz. The fatigue performance was determined and compared to that of another Al-alloy produced by L-PBF. Specimens were examined by using optical microscopy and SEM analysis to determine the microstructure. The fracture surfaces of vertical specimens were investigated in the SEM to determine the mechanisms of crack initiation.

Fatigue crack initiation and propagation of wire arc additive manufactured Al-Mg alloy

Wire arc additive manufacturing technology has many advantages in producing large engineering structures and is being applied in aerospace structures. It is necessary to explore the fatigue failure mechanism of wire arc additive manufactured aerospace aluminum components to ensure these structures' safe application. Crack initiation and propagation behavior for wire arc additive manufactured Al-Mg alloy are investigated under fatigue loading. The microstructure characteristics of different regions are analyzed by metallographic and electron back-scattered diffraction measurements. The fatigue test results show that multi-crack initiation is the fatigue damage characteristic for the additive manufactured parts. The small cracks are distributed in the deposition and layer band zones, and the number of small cracks increases with the cyclic numbers. The main crack initiates from the coarse columnar grain boundaries in the deposition zone, and the final fracture is in the strain concentration zone. The fatigue fracture morphologies show that the fatigue cracks initiate at the pores, non-melted particles, and grain boundaries.

Plasma Welding of Aluminum in an Oxygen-Free Argon Atmosphere

Abstract Plasma welding is characterized by a high concentration of energy, which allows for high welding speed and leads to less distortion and residual stresses compared to conventional welding processes. Due to the local and controlled heat input, the process is suitable for sheet metal from ≈ 0.1 mm (micro plasma) up to ≈ 10 mm. In the case of aluminum and its alloys, the natural aluminum oxide layer on the metal surface limits the productivity of the plasma welding process. The electrically isolating and thermally insulating Al2O3 layer has a significantly higher melting point compared to the aluminum (T m(Al2O3) = 2072 °C vs. T m(Al) = 660 °C). The oxide layer hinders the formation of a stable arc and can even impede the joining formation. In order to remove the oxide layer and to produce quality welds with a DC process, it is necessary to weld with reverse polarity to use the principle of cathodic surface cleaning. However, this leads to increased electrode wear and increased penetration depth, which is not always desirable. In the study presented, the use of silane to reduce the oxygen content in the welding atmosphere as well as to remove the natural aluminum oxide layer on the metal surface was investigated. As previous studies have shown that the use of silane-doped plasma-gases is suitable for removing the superficial oxide layer on aluminum components, high-quality welded joints were expected. Quality welds with sufficient dilution were achieved using a transferred arc silane-doped helium plasma. In contrast, welding with an argon-silane mixture led to excessive pores formation. Additionally challenges to stabilize the arc process were identified and ramifications with respect to process optimization are discussed.

Characterization of the Tribological Behavior of Different Tool Coatings and Dry Lubricant for High‐Strength Aluminum Alloys at Elevated Temperatures

The use of high‐strength aluminum components in automotive manufacturing offers the opportunity to reduce vehicle weight significantly and provide new lightweight potentials. In the past, the so‐called hot forming and quench process (HFQ) successfully demonstrates the potential for the production of complex‐shaped components made out of age‐hardenable high‐strength aluminum alloys. Currently, no method permits wear‐free quench forming without the use of lubricants. To fulfill the increasing ecological and economic requirements, it is necessary to identify wear‐reducing techniques to promote this forming technology in the future. This contribution investigates the interaction of lubricant and tool coatings on the tribological performance during quench forming of the high‐strength aluminum alloy AA7075 at elevated temperatures. For this purpose, the tribological behavior is investigated using both, flat strip drawing tests and deep drawing operations. Subsequently, the component quality is compared and discussed. The results demonstrate that tool coatings are effective for the production of high‐strength components in the HFQ process with minimal or even no lubrication and thus provide ecological as well as economic advantages.

IntelliScan: Improving the quality of x-ray computed tomography surface data through intelligent selection of projection angles.

X-ray computed tomography (XCT) enables the dimensional measurement and inspection of highly geometrically complex engineering components that are unmeasurable using optical and tactile instruments. Conventional XCT scans use a circular scan trajectory where X-ray projections are acquired with a uniform angular spacing; this approach treats all projections as being of equal importance, in practice, some projections contain more object information than others. In this work we capitalize on this concept by intelligently selecting projections with a view to improve the quality of surface models extracted from an XCT data-set. Our approach relies on using a priori object information to select X-ray projections in which the surfaces of the object are aligned with a ray-path, thus ensuring the surface of the object is fully sampled. Results are presented showing that the proposed method is able to reduce CAD comparison errors by 16%, reduce surface form error by 3%, and improve edge contrast by 14% for a machined aluminium component.

Antifrictional Effects of Group IVB Elements Deposited as Nanolayers on Anodic Coatings

The utilization of anodized aluminum (Al) components would contribute greatly to combat against dry friction if good tribological properties could be attained. Despite its hardness, the wear rate of anodic coatings presents a major problem in many applications, including automotive, aerospace and high-tech industries. Recently, nanolayers of Ti demonstrated high tribological effectiveness and unusually low dry friction on anodic coatings. However, few researchers focus on the tribological characterization of nanolayers of other elements. In this study, nanolayers of Ti, Zr, Hf, Cu, Cr, Nb and Sn were deposited on anodized 1050 and 6082 alloys by magnetron sputtering and Atomic Layer Deposition. Major attention was devoted to surface roughness and hardness measurements, because of their importance for static friction. The results showed that structural, chemical and other intrinsic properties of nanolayers of Group IVB elements in many cases led to significant friction reduction, when compared to those of Cu, Cr and Hf. Nanolayers of 15 nm to 75 nm thicknesses appeared most effective tribologically, while 180 nm or thicker layers progressively lost their ability to sustain low dynamic friction. Deposition of nanoscale structures could provide advantages for the anodized Al industry in protection against incidental friction and wear.

Data sets for "Aluminum components in bridgmanite coexisting with corundum and the CF-phase with temperature"

data sets for "Aluminum components in bridgmanite coexisting with corundum and the CF-phase with temperature"

Aluminum Components in Bridgmanite Coexisting With Corundum and the CF‐Phase With Temperature

AbstractPhase relations in the MgSiO3–MgAl2O4–Al2O3 system are investigated at 27 GPa and 2000–2600 K using a multi‐anvil apparatus. The AlAlO3 content in the bridgmanite increases from 8.6 to 20.0 mol% with increasing temperature from 2000 to 2600 K, while the MgAlO2.5 content remains nearly constant, that is, 3–4 mol% at these temperatures. Therefore, the presence of an additional Al‐bearing phase suppresses the oxygen vacancy substitution for Al3+ in bridgmanite. Conversely, significant amounts of the Al8/3O4 component can be dissolved into the calcium‐ferrite type MgAl2O4–Mg2SiO4–Al8/3O4 phase (CF‐phase), implying that the CF‐phase likely contains some amount of vacancies. Therefore, the CF‐phase could also be a candidate mineral for transporting volatiles into the lower mantle. Our results, combined with previous studies on Al‐bearing bridgmanite, indicate that, once the Al per formula unit exceeds 0.12 in bridgmanite, the MgAlO2.5 content remains nearly constant and the AlAlO3 component becomes dominant.

Criteria of structural durability proof regarding testing time for substituting of steel by aluminium components by the example of commercial vehicle wheels

AbstractDer experimentelle Nachweis der Betriebsfestigkeit von Sicherheitsbauteilen stützt sich auf eine schädigungsäquivalente Reduzierung des Bemessungskollektives auf ein Versuchskollektiv mit verkürztem Umfang unter Berücksichtigung statistisch begründeter Sicherheitsfaktoren. Historisch bedingt, wurden entsprechende Versuchskollektive zunächst für Bauteile aus Stahl anhand von Wöhlerlinien für Stahl, durch Anwendung der Palmgren‐Miner Regel mit der Modifikation nach Haibach, vorgenommen. Bei der späteren Einführung von Aluminiumbauteilen stellte sich allerdings die Frage, ob der für Stahlbauteile entwickelte Sicherheitsnachweis ohne Änderung übernommen werden kann. Bedingt durch die gegenüber Stahl unterschiedlichen Neigungen der Wöhlerlinien vor und nach dem Abknickpunkt, ergeben die für Stahlbauteile abgeleiteten Versuchskollektive bei Aluminiumbauteilen eine geringere Schädigung im Vergleich zum Bemessungskollektiv. Aus diesem Grund muss, bei Verwendung eines für Stahlbauteile entwickelten Versuchskollektives oder einer Erprobungsstrecke, der geringeren Schädigung bei Aluminiumbauteilen mit einer Erhöhung der Versuchslaufzeit begegnet werden. Am Beispiel von Nutzfahrzeugrädern aus Stahl und Aluminium mit vergleichbaren höchstbeanspruchten Stellen werden die werkstoffbedingten Sachverhalte im Hinblick auf die Versuchslaufzeit für Aluminiumbauteile dargestellt.

Mechanical performances of the interface between the substrate and deposited material in aluminium wire Direct Energy Deposition

Wire and Arc Additive manufacturing (WAAM) is a Direct Energy Deposition process suitable for the manufacture of large aluminium components. Additive Manufacturing can enable the production of functionally graded structure which could be done by integrating the substrate required to start the deposition into the final component. This paper aims to assess the possibility of including a substrate in a component by investigating the mechanical performances of the interface between a wrought plate and WAAM deposit. Four substrates alloys and 2319 WAAM alloy were investigated. Inter-layer rolling and heat treatment, process steps known for improving the properties of WAAM deposit, were implemented. Each interface was examined using microhardness profiles, tensile tests, post rupture fractography and microstructural analysis. The WAAM deposit hardness was lower than that of the substrate in the as-deposited condition. Although the interface had no impact when using the same alloy for both substrate and wire, the weakest point of the combination was at the interface in dissimilar alloy combination. Heat treatment reduced the properties difference between the substrate and WAAM deposit. Inter-pass rolling strengthen the WAAM deposit without impacting the substrate and eliminated the micro crack that occasionally formed in the fusion zone in the as-deposited condition.

Adaptive inspection planning using a digital twin for quality assurance

The integration of a digital twin into inspection planning enables a novel procedure that reduces avoidable inspection times and costs. This paper shows a method for component-specific adaption of inspection plans by feeding back data-based quality results into inspection planning. An initial evaluation of the method on a real aerospace aluminum component is carried out using a 3-axis milling process. Machine learning based quality models were implemented for the inspection features shape deviation and surface roughness. With the knowledge gained, the inspection time for the process can be reduced by up to 75 % per component.

Effects of bauxite tailings and sodium silicate on mechanical properties and hydration mechanism of magnesium phosphate cement

Aiming at the problem of poor water resistance of magnesium phosphate cement (MPC) and large amount of bauxite tailings (BTs) accumulation, the effects of BTs and sodium silicate (NA) on mechanical properties and the hydration mechanism of MPC are investigated. The experimental results show that adding 15.0 wt% BTs can decrease the production cost without decreasing the strength of MPC, while NA can enhance the strength and water resistance of MPC with BTs, delay the setting time, and decrease the cumulative heat release during hydration. The compressive strength reaches 42.6 ± 0.4 MPa after curing in air for 28 d. Microanalysis shows that the main hydration product is struvite-K (MgKPO4·6H2O). NA can activate BTs, release silicon and aluminum components from BTs, and produce the zeolite-like hydration product sodium silicate aluminate hydrate (N-ASH) gel. Adding BTs and NA to MPC reduces the generation of microcracks and makes matrix more compact. Therefore, this work not only improves MPC performance, but also promotes the resource utilization of BTs.

Improving the irradiation resistance of inverted flexible 3J solar cells by adjusting the structure

Highly efficient, flexible, and lightweight thin-film solar cells play an important role in the aerospace field. To improve the radiation resistance of GaInP/GaAs/InGaAs triple-junction inverted metamorphic (IMM3J) solar cells under intense electron irradiation in space, the back field of the top cell and band gap of the middle cell were optimized. Under 1 × 1015 e/cm2 electron irradiation, compared with the reference cell, the attenuation of the conversion efficiency of the backfield-optimized cell and bandgap-adjusted cell was reduced by 10.3 % and 2.8 %, respectively. According to the spectral response and electrical properties, the current-limiting units of the different cells before and after irradiation were analyzed. The increase in the aluminum (Al) component increased the barrier of the AGaInP back surface field, promoted the carrier absorption of the top cell, and increased the initial current of the solar cell. Optimization of the bandgap in the middle cell enables the bottom cell with a redundant current to resist irradiation attenuation. Both adjustments optimize the current-matching relationship between the sub-cells after irradiation. The decay coefficient of the minority carrier was calculated using the electrical displacement damage theory, and the lifetime decay coefficient of the minority carrier was further estimated, which indicated that the radiation resistance was improved. In addition, the mechanism of improving the radiation resistance is discussed in detail by the characteristics of carrier transport, which provides an optimal direction for improving the irradiation characteristics of solar cells in the future.

Feasibility study of a novel multi-container extrusion method for manufacturing wide aluminium profiles with low force

Extrusion profiles are extensively used in industries and any improvement in the process could potentially have a large impact on energy and cost savings. In this study, a novel extrusion method, namely multi-container extrusion, was proposed for producing thin-walled wide aluminium components with low force. Its basic principle is to enable multiple billets to be welded and forced through die orifice simultaneously. To demonstrate its feasibility, a series of studies have been conducted including the experimental design and set-up of multi-container extrusion, microstructural and mechanical characterisations of the extruded components, and the comparison with the existing extrusion method. A three-container extrusion tooling was designed and manufactured to produce wide hollow profiles with plasticine and aluminium alloy AA6063. Optical microscopic observations and tensile tests were carried out for different positions of AA6063 extrudates. For the specimens near the extrudate front (8 mm and 23 mm away), tensile fractures occurred exactly along the distinct welds which were formed when individual billets met inside the die during extrusion. Further away from the extrudate front (83 mm, 98 mm and 113 mm), the welds were hardly observed, and the tensile fractures occurred outside the welds, indicating that good welding quality can be obtained in the multi-container extrusion process. Compared with the conventional porthole extrusion method, three-container extrusion could significantly reduce the required force to about 15 % for extruding the same profile. This study demonstrates that the proposed multi-container extrusion method can form wide profiles and greatly reduce the extrusion force requirement.

Hydrogen Recovery from Waste Aluminum–Plastic Composites Treated with Alkaline Solution

An alternative solution to the problem of aluminum-plastic multilayer waste utilization was suggested. The process can be used for hydrogen generation and layer separation. Three different sorts of aluminum-plastic sandwich materials were treated with an alkali solution. In the temperature range of 50-70 °C, for tablet blisters of polyvinylchloride and aluminum (14.8 wt.%), the latter thoroughly reacted in 15-30 min. For sheets of paper, polyethylene, and aluminum (20 wt.%), full hydrogen 'recovery' from reacted aluminum component took 3-8 min. From the lids of polyethylene terephthalate, aluminum (60 wt.%), and painted polyethylene with perforations, the aluminum was consumed after 45-105 min. The effect of perforations was the reduction of the process duration from nearly 90 min for the lids with no perforations to nearly 45 min for the perforated ones (at 70 °C). Perforations provided better contact between the aluminum foil, isolated between the plastic layers, and the alkali solution. Hydrogen bubbles originating near those perforations provided foil separation from the upper painted plastic layer by creating gas gaps between them. The remaining components of the composite multilayer materials were separated and ready for further recycling.

Renovating Modern Heritage

The post-war building stock is increasingly being transformed. Even at objects protected as listed heritage, renovation usually results in a high degree of material exchange and replacement. This is especially the case in regard to historic curtain wall constructions. Based on the case study of the Commerzbank High-rise and original planning documents by Gartner, the paper focuses on the applied strategy of disassembling and reassembling the curtained aluminium sandwich elements, and the resulting upgrading of the original façade with a newly installed interlayer for insulation. The paper discusses the possible transfer of this strategy, which largely depended on the existing high quality of the aluminium components, their corrosion-resistant properties and low weight. The case study of the former Commerzbank High-rise indicates that a long-term preservation of post-war modern building stock can be achieved without wholesale replacement of original building components. The reuse of existing materials and components represents a promising approach.

Non-destructive Evaluation of Workpiece Properties along the Hybrid Bearing Bushing Process Chain

To combine the advantages of two materials, hybrid bulk metal workpieces are attractive for subsequent processes such as metal forming. However, hybrid materials rely on the initial bond strength for the effective transfer of applied loads. Thus, a non-destructive evaluation of the bonding along the production process chain is of high interest. To evaluate to what extent non-destructive testing can be employed to monitor the bonding quality between the joining partners steel and aluminum and to characterize the age hardening condition of the aluminum component, ultrasonic testing and electrical conductivity measurements were applied. It was found that a lateral angular co-extrusion process can create homogeneous bonding although the electrical conductivity of the aluminum is altered during processing. A previous bonding before the subsequent die forging process leads to a sufficient bonding in areas with little deformation and is therefore, advantageous compared to unjoined semi-finished products, which do not form a bonding if the deformation ratio is too small. An influence of the subsequent heat treatment on the bonding is not visible in the ultrasonic testing signals though a homogenized electrical conductivity can be detected, which indicates uniform artificial aging conditions of the aluminum alloy

Form of the Occurrence of Aluminium in Municipal Solid Waste Incineration Residue—Even Hydrogen Is Lost

In the bottom ash (BA) of municipal solid waste incineration, the content of iron and aluminum is relatively high. The efficiency of eddy current extraction of non-ferrous metals (including aluminium) routinely used in incineration plants is limited. The determination of the form of occurrence of aluminium or aluminium-rich components in BA is important in terms of its recovery or utilisation. BA from a newly built incineration plant in Poland was analysed using chemical analysis, X-ray diffraction, optical microscopy, and scanning electron microscopy with chemical microanalysis. Samples of water-quenched BA were analysed. For comparison, a non-quenched sample (collected above a water tank) was analysed. The obtained results indicate that aluminium-rich components in BA are present in both the melt phase and quench phase. In the melt phase (glassy material), the content of aluminium is low (usually below 2 wt%). Aluminium-rich components present in glass, inherited after aluminium products are usually oxidised, and occur as platy or irregular forms. Aluminium components in the quench phase are significantly transformed with the common presence of Cl− and SO42− phases formed during reaction with the quench water. Secondary phases form simple or complex rims around metallic or slightly oxidised cores, of which the size is significantly reduced during transformations. The variety in the forms of aluminium occurrence in BA makes its recovery challenging and inefficient. The reduced content of metallic aluminium indicates that the potential for hydrogen generation of BA is low.

Influence of the mold type on the mechanical properties of the piston alloy with nano alumina in casting and metal mold

This research is an experimental comparison study to show the influence of mold type casting on mechanical properties. The study considers the aluminum alloy of a gasoline engine piston with nanoparticles alumina Al2O3 size 25 nm manufactured in two types of molds. Sand mold and cast-iron mold were selected to cast the aluminum composite components. A systematic comparative study of tensile strength and hardness properties of cast aluminum components is made on sand and metal molds production. The nano powder can add to enhance the mechanical properties must not exceed 4 % for metal and sand mold casting. According to data for hardness, adding nano alumina powder has minimal impact on metal mold casting, but it significantly improves sand casting. From a financial standpoint, metal casting provides higher economic values for making piston aluminum castings. The hardness rises as the alumina content does in two molds as compared to the obtained specimen. It demonstrates that the highest hardness occurs at 4 % alumina in the sand-casting mold and at 6 % alumina in the metal. When the compositions of the casting materials are the same, a comparison of the fracture morphology between sand and mold casting reveals more ductile fractures for metal molds compared to brittle fractures in sand cast by large silicon separation grains because of higher grain growth in sand casting by longer solidification time. The same is seen in mold casting, which exhibits reduced ductility due to the alumina nanoparticles' dispersion strengthening process in the aluminum matrix. This arises as a result of nano alumina dispersion acting as barriers to dislocation motions in the aluminum matrix, enhancing strength but reducing ductility.

Assessment of Mechanical and Optical Properties of Al 6060 Alloy Particles by Removal of Contaminants

The use of aluminum as a light‐weight construction material in automotive engineering has increased steadily in recent years among other sectors. However, the production of primary aluminum requires significantly more energy than the production of steel, which motivates the recycling of existing aluminum components. Based on the results of past investigations, this interdisciplinary study expands the potential applications of a friction‐induced solid‐state recycling process to reduce the amount of energy, which is needed in the aluminum production and thus also to reduce the CO2 footprint of the industrial sector. To increase the processability of different conditions of the aluminum chips, a chemical pretreatment was performed to remove an applied cooling lubricant. This study shows that under the use of the chemical cleaning method presented here, it is possible to improve the mechanical properties significantly.