Cast Aluminum Alloy Research Articles

Influence of High-Speed Ram Transition Position on Porosity and Mechanical Properties of Large One-Piece Die-Casting Al-Si-Mn-Mg Aluminium Alloy

The high-pressure die-casting process can effectively manufacture aluminium alloy castings with complex shapes and thin wall thicknesses. However, due to the complex flow characteristics of the liquid metal during the mould-filling process, there are significant differences in the mechanical properties of different parts of the casting. This paper analyses the effect of the high-speed ram transition position on porosity and mechanical properties of Al-Si-Mn-Mg aluminium alloys in the high-pressure die-casting (HPDC) process, comparing the 1160 mm and 1200 mm positions. Using a comprehensive methodology that combines CT, tensile tests, and SEM, the research demonstrates that the 1160 mm position improves mechanical properties and reduces porosity, with a larger gap at the near-end of the casting, where the yield limit and elongation of the casting increased by 13% and 25% at 1160 mm compared to 1200 mm, respectively. This result shows that appropriate adjustment of the high-speed ram transition position can effectively optimise the organisational structure of thin-walled castings, and then improve their mechanical properties.

Exploring the Effects of Open-Air Cooling on the Formation of Microstructure in Cast A356 Aluminum Alloy

The lightweight composition, non-magnetic nature, and machinability of aluminum alloy A356 make it an important material in many industries due to its significant mechanical properties such as strength, ductility, fatigue resistance, and castability. Aluminium alloy forms an oxide layer when exposed to air. The microstructure of this alloy plays a critical role in determining its mechanical behavior. This study utilized aluminum alloy A356, composed of 92.05% aluminum, 7% silicon, 0.35% magnesium, 0.20% copper, 0.10% manganese, and 0.10% zinc. This alloy exhibits extremely high corrosion resistance, similar to stainless steel, with a melting point of 650°C. The study examines multi- component (mainly Al with Si) A356 containing small amounts of Mg, Cu, Mn, and Zn for their complex microstructural behavior. It includes observations using techniques such as optical microscopy and X-ray diffraction (XRD). This research was carried out to investigate different areas of the same metal’s microstructure and to discover the influence of cooling rates during the solidification process. The findings revealed that there are dissimilarities between the central parts and outer areas, as well as similarities between the two side portions. Also, this study highlights processing conditions’ impact on the material response while looking at heat transfer rate effects during solid-state transformation. The findings of this study highlight the presence of distinct microstructures (dendritic and equiaxed structures) across different sections of the cast Aluminum alloy A356. These findings contribute to a better understanding of the microstructure-property relationship of Aluminum alloy A356, assisting in improvising design and manufacturing processes for enhanced performance.

Analysis of Different Commercial Solid Fluxes Used During the Rotary Degassing Melt Treatment of Casting Aluminum Alloys

AbstractThis work aimed to get a better understanding of the behavior and melt cleaning efficiency of different commercial solid fluxes used in the foundry industry for the treatment of liquid aluminum alloys. This was realized by combining industrial melt treatment experiments with the application of characterization techniques that can provide information about the phase composition and thermal stability of different fluxes. Rotary degassing treatments coupled with flux addition using 5 different commercial fluxes were conducted on batches of EN AC-46000 alloy (AlSi9Cu3(Fe)) melt. The melt quality was assessed by the Qualiflash technique and Bifilm-Index (BI) analysis of reduced pressure test (RPT) samples. The phase composition and thermal behavior of the fluxes were investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA), respectively. Among the 5 fluxes, two had a rather similar phase composition with the main constituents being NaCl, KCl, CaF2, MgF2, Na2CO3·NaHCO·3H2O, Na2SO4, and K2SiF6. These two fluxes, which contain a relatively high amount of fluoride components (about 11mol pct), and had a melting temperature below 600 °C, proved to be the most efficient in improving the melt quality. The Quality Temperature Index (QTI) values and normalized Bifilm-Index (NBI) results of the RPT samples generally showed a similar tendency, but there was only a loose relationship between the two parameters. Discrepancies between the results of different melt quality evaluation techniques can be traced back to their sensitivity to melt quality changes.

Effect of Graphene Addition on Microstructure and Mechanical Properties of Cast Aluminium Alloy Composite

Aluminium-reinforced metal matrix composites (Al-MMCs) are highly desirable because of their low density, excellent corrosion resistance, high thermal and electrical conductivity, high strength, and stiffness. This research intends to improve the mechanical properties of Al-MMCs for lightweight automotive and aerospace applications. A Taguchi method with two parameters and four levels was used to determine the optimum amounts of graphene nanoplatelets (GNPs) (0.1, 0.25, 0.5, and 0.6 wt%) and stirring duration (1, 2, 4, and 8 minutes). GNPs were added to the molten aluminium alloys through the stir-casting process to enhance the mechanical properties of the Al-MMCs. The results revealed that the Al-MMCs with 0.25 wt% GNPs and 8 minutes of stirring time produced the highest value of hardness and tensile properties. Under these parameters, the microstructure changed from dendritic to rosette, which had a tremendous effect on the improvement of the mechanical properties. The Ultimate Tensile Strength (UTS) and Yield Strength (YS) of the samples were improved after T6 heat treatment with a value of 210.26 MPa and 145.31 MPa, respectively, and the hardness was 116 HV while the elongation to fracture was 4.89%. The results showed that the high GNP concentration improved the mechanical properties of the Al-MMCs.

Surrogate-assisted optimization under uncertainty for design for remanufacturing considering material price volatility

Remanufacturing is a well-established end-of-life (EOL) strategy that promises significant savings in energy and carbon emissions. However, the current design practices are not remanufacturing-inclusive, i.e., the majority of products are designed for a single life cycle. As a result, potential products that can sustain multiple life cycles are deprived of additional benefits of being designed for remanufacturing, such as reduced material usage, lower cost, and improved environmental impact. Moreover, the uncertainty in design, material selection, and economics are not considered to produce remanufacturable designs. Accordingly, this research proposes a design for remanufacturing (DfRem) framework that accounts for design uncertainty and material price volatility. The framework systematically explores the design space, performs design optimization under uncertainty, followed by topology optimization to provide additional mass savings, and finally, a price volatility analysis for plausible design material choices. The candidate designs are evaluated based on their design mass, material price volatility, failure mode characteristics, carbon footprint, and embodied energy impacts. The proposed framework's utility is demonstrated via the use of an engine cylinder head case study subjected to thermo-mechanical loads along with fatigue and wear failure. Considering grey cast iron and aluminum alloy as the design material choices, it was found that the cast iron design reduced the initial design mass by 6% as opposed to a 5% decrease for aluminum. On the other hand, about 8% area of the cast iron design failed due to fatigue, compared to 3% for aluminum. We further observed that although the aluminum design provided better mechanical performance than the cast iron design, this material was more expensive and volatile in price.

Synergistic effects of boron carbide and eggshell particles on mechanical and tribological properties of ultrasonic-assisted stir cast aluminium alloy based composites

Aluminium matrix composites are in high demand for their lightweight nature and favourable properties, yet issues like high thermal expansion, low microhardness or high cost often challenge them. To address these limitations, the integration of sustainable, cost-effective reinforcing agents that can enhance hardness and wear resistance can be explored, as this can broaden the application scope of these composites across various industries. The present study fabricates aluminium matrix composites with aluminium alloy (AA6063-T6) as a matrix and different wt.% (0%, 2% and 4%) of micro-sized eggshell (ES) and boron carbide (B4C) particles as reinforcements through ultrasonic-assisted stir-casting. Analysis of microstructure, mechanical and tribological properties of the fabricated composites are done and compared to those of the as-cast base alloy. Results from optical and scanning electron microscopy (SEM), together with energy-dispersive X-ray spectroscopy (EDS) analysis, revealed the uniform distribution of reinforcements in all three composites. X-ray diffraction (XRD) indicated the formation of several compounds in each composite. Among all, the as-cast base alloy exhibited the lowest porosity at 0.48%. The AA6063-T6/B4C composite demonstrated the highest hardness, with an increase of 46.08%, while the AA6063-T6/ES/B4C composite achieved the highest tensile strength, showing a 62.28% improvement compared to the as-cast base alloy. As the load increased from 20N to 60N, the wear rate of the reinforced composites rises while the coefficient of friction decreased, with the AA6063-T6/B4C composite showing the highest wear resistance.

Tool wear and surface characteristics of TiAlN/AlCrN insert in high-speed turning of bimetal aluminium alloy-grey cast iron engine block

This study investigates the tool wear and surface characteristics of TiAlN/AlCrN-coated inserts during high-speed turning of aluminium alloy and grey cast iron (GCI) in engine blocks. Cutting performance was evaluated at a constant speed of 1,130.4 m/min and a feed rate of 0.18 mm/rev over 300 shots (the number of intermittent cuts). SEM-EDX and roughness analysis revealed abrasion and adhesion as the main wear mechanisms, with a maximum flank wear of 1.14 mm, primarily due to GCI’s abrasive nature. Surface roughness measurements for aluminium HD2 and GCI were 7.09 µm and 9.15 µm, respectively. The results highlight the effectiveness of TiAlN/AlCrN coatings but show eventual breakdown under GCI, offering insights for improving tool design in bimetal machining.

Research on frozen sand mold casting technology for complex thin-walled aluminum alloy castings

With the growing emphasis on environmental sustainability and the modernization of the manufacturing sector, the pursuit of eco-friendly practices within the foundry industry has become a critical objective. This paper proposes an innovative solution for environmentally friendly casting: the digital frozen sand mold casting technology. To evaluate its effectiveness, this study analyzed complex thin-walled grid rudder aluminum alloy castings. A comparative analysis was conducted between the binder jetting 3D printing and frozen sand mold (sand mold milling) casting processes. By utilizing Anycasting software, the research explored the filling and solidification processes of ZL101 grid rudder castings under varying mold conditions, aiming to predict the distribution and severity of shrinkage defects. Validation of this approach indicated a machining error of ±0.25 mm for frozen sand molds. The dimensional accuracy of the grid rudder castings achieved a casting tolerance grade of 9 (CT9), and the direct recovery rate of used sand exceeded 98 %, thus positioning this method as a viable alternative to 3D-printed resin sand. Additionally, the study assessed the economic feasibility of frozen sand mold casting technology in terms of resource consumption and production efficiency. The research findings hold significant relevance, offering valuable insights and guidance for traditional casting enterprises seeking to adopt sustainable development practices through the application of leveraging frozen sand casting technology.

Effect of in-situ submicron Al3Ti particles on grain refinement and strengthening of Al–Zn–Mg–Cu-based alloy

Extensive research has been conducted to improve the efficiency for grain refinement of aluminum cast alloys. Herein, we propose a novel strategy to significantly reduce the cast grain size using in-situ submicron Al3Ti particles. The ZnO nanoparticles with enhanced wettability via mechanical stirring process provide finely dispersed α-Al2O3 particles, which serve as heterogeneous nucleation sites for primary Al3Ti particles. A large number of primary Al3Ti nuclei are formed from the α-Al2O3 particles without coarsening even under a relatively slow cooling rate. As a consequence, the size of Al3Ti particles was reduced to approximately 600 nm, resulting in the fine cast grain size of approximately 20 μm. Furthermore, a sheet made of the refined cast alloy has reduced recrystallized grain size and simultaneously improved strength and ductility.

Improving heat transfer in an air-cooled engine by redesigning the fins

Heat transfer modelling and simulation were carried out in a single-cylinder, four-stroke, air-cooled engine to evaluate the heat transfer rate of the engine block. The modelling studies of cylinders with different numbers of fins and different geometry were performed using the SolidWorks computer platform. The tested components were made of 6063-T6 aluminium alloy castings. The simulation concerned different numbers of fins as well as changing the geometry of fins with circular and rectangular perforations. The results of the studies showed the possibility of improving the power to mass ratio for cylinder efficiency and heat transfer rate. It was shown that a large number of fins leads to an increased heat transfer rate, but it affects the overall engine efficiency due to the increase in the total engine mass. Circular perforation is a better design solution than rectangular perforated fins with the same cross-section. Circular perforation provides a lower engine cylinder mass and gives more than 4 % better heat transfer rate. The perforation size was tested using circular perforations with a diameter of 7.14 mm, 8.5 mm and 10 mm. With a 7.14 mm diameter perforation the heat transfer rate increases slightly compared to the other tested ones, while a 10 mm diameter perforation provides the best mass reduction.

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

Enhancement of Mechanical Properties and Microstructure of Aluminium alloy AA2024 By adding TiO2 Nanoparticles

Modern engineering applications, especially in the automotive and aerospace industries, require essential and appealing properties such as lightweight with high strength and resistance. The key objective of the present study is to investigate the effect of TiO2 nanoparticles on the microstructure, impact strength, hardness and wear resistance of the stir cast aluminum alloy AA2024, An aluminium alloy was reinforced with different mass fractions (0 %, 2.5 %, 5 %, 7.5 %) of titanium dioxide nanoparticles by stir casting followed by solution annealing at 500°C for 3 h, quenching in water and aging at 175°C for 3 h. Results showed that regular morphology and fine grain size of primary AA2024 particles are achieved after the addition of 2.5 wt.% TiO2 compared to the sample without the addition of nanoparticles composite. In addition, it was found that adding nanoparticles increased energy absorption, and this effect is improved by increasing impact strength by adding nanoparticles, the impact strength increased from 5 j/m2 to 7 j/m2 at 5%. At the same time, the increase of nanoparticles effect decreases the mass losses (increase in wear resistance). With a weight fraction of 5 wt.% TiO2, the alloy exhibits the highest value of hardness.

SEM-DIC characterization of the damage mechanism of an AlSi10Fe0.7 casting alloy on the microstructure scale

Various brittle phases are present in commercial cast aluminum alloys, which strongly influence their mechanical behavior. Among these, silicon precipitates are nearly omnipresent, as Si is a common alloying element. In secondary alloys, usually Fe-containing phases cannot be avoided, and they tend to degrade the mechanical properties. The interaction between the silicon phase and the failure-critical intermetallic phase in the Al-Si-Fe phase system (β-Al5FeSi) is studied in this paper in high resolution. A model alloy AlSi10Fe0.7 was defined, which is composed of a large grain Al-matrix, Si-precipitates and the plate-like β-Al5FeSi phase. The goal of the study was to identify “hot spots” in the microstructure from which cracks may initiate under mechanical loading. The main tool was a deformation analysis via digital image correlation in the SEM (SEM-DIC). This allows the identification and tracking of developing strain localizations at different potential crack initiation sites with a high resolution as well as capturing an overview over the whole specimen. An adapted frame averaging script minimized measurement errors induced by drift. The SEM-DIC results show that the deformation field is governed by the elastic incompatibility of the microstructural constituents. Crack initiation occurs because of the detachment of the Si + β-Al5FeSi phase boundary. Cracks then cross the phase boundary and propagate along twin boundaries in the β-Al5FeSi phase. Final failure is caused by linking fractured brittle plate-like particles.

On the Competition between Pores and Hidden Entrainment Damage during In Situ Tensile Testing of Cast Aluminum Alloy Components

The competition between pores and hidden entrainment defects during tensile testing of specimens from Al-Si-Cu alloy high-pressure die castings has been characterized. In all tests, multiple strain concentrations have been identified by using the digital image correlation technique and the final fracture has been preceded by a competition between pores and hidden damage, later identified as oxide bifilms. The results have confirmed previous findings that overall damage to the metal during its liquid state is much more extensive than what can be assessed via X-ray inspection, which looks only for pores. It is concluded that current quality assurance techniques need to be updated.

Surface defect detection method of aluminium alloy castings based on data enhancement and CRT‐DETR

AbstractThe surface quality of aluminium alloy castings is crucial to quality control. Aiming to address the challenges of limited samples and extensive computation in deep learning‐based surface defect detection for aluminium alloy castings, this paper proposes a surface defect detection method based on data enhancement and the Casting Real‐Time DEtection TRansformer. First, to tackle the issue of small sample sizes and uneven distribution in surface defect data sets of aluminium alloy castings, ECA‐MetaAconC Deep Convolution Generative Adversarial Networks is proposed for generating defects with fewer samples and employ the image augmentation (IMGAUG) library for sample enhancement. Second, building upon the Real‐Time DEtection TRansformer (RT‐DETR), a lightweight partial‐rep convolution is designed to decrease the network's parameter count. Simultaneously, the Deformable attention module and the DRBC3 module are introduced to enhance the neck network, thereby improving the model's capability to capture information and enhancing its detection performance. Compared to RT‐DETR, this method reduces the number of model parameters by 38.7%, increases mAP by 1.5%, and achieves a frame rate that is 1.58 times higher than the original model. The experimental results demonstrate that this method can effectively and accurately detect surface defects in aluminium alloy castings, satisfying industrial requirements.

Overview on aluminium alloys as sinks for end-of-life vehicle scrap

Abstract A fundamental principle in metallurgy is that the higher the purity of metals and alloys, the more favourable their properties will be. However, as the recycling of materials in production becomes increasingly significant, the levels of impurities are also on the rise. In the case of aluminium, the consequences can be detrimental due to the low solubility of most elements in this metal, which leads to the formation of brittle intermetallic phases (IMPs). Moreover, once impurities have entered aluminium, it is difficult to remove them. In 2017, almost 100 million cars were produced worldwide. Historically, vehicle design prioritised performance, resulting in a multi-material mix to utilise the best materials for each application. This included over 40 different wrought and cast aluminium alloys, Cu-based materials for electrics, and steels for high-strength applications. In the recycling of end-of-life vehicles (ELVs), high purity wrought Al alloys are today down-cycled to low purity cast engine blocks. However, recent advancements show that the drawback of increase IMP-fractions can be turned into benefits through the strategic design of heterostructured alloys. A first successful alloy example from this approach enables interesting forming properties, previously only found in 5xxx series wrought aluminium alloys, in combination with a matrix composition and age-hardening potential known from 6xxx series wrought aluminium alloys. A second examples reviews compositions directly resulting from ELV scrap. By manipulating IMPs it is feasible to create heterostructures with an interesting balance of strength and ductility. These approaches challenge traditional views, allowing for a greater volume fraction of intermetallic phases. Understanding the formation and role of intermetallic particles is crucial. This work gives an overview to the current problem and the state of the art and addressed the potential of upcycled aluminium alloys that tolerate high impurity levels by using intermetallic phases as impurity sinks.

Nanotechnology enabled casting of aluminum alloy 7075 turbines

Aluminum alloy 7075 is well-known for its high-performance structural systems due to its lightweight and excellent mechanical properties. However, its susceptibility to hot cracking and limited fluidity hinder its casting suitability, posing challenges in manufacturing near-net-shaped structures economically, especially for thin and intricate aerospace components. This paper presents experimental results based on nano-treating, an emerging nanotechnology-enabled manufacturing method by incorporating a low fraction of nanoparticles in liquid aluminum, to allow the casting of complex aluminum alloy 7075 parts. Vacuum fluidity tests demonstrated that nano-treating of aluminum alloy 7075 with only 0.5 vol% TiC nanoparticles increased the fluidity of aluminum alloy 7075 by more than 20%, effectively eliminating hot cracking and enhancing surface quality. Through the Rapid Investment Casting process, nano-treated aluminum alloy 7075 can be successfully cast into turbines with 0.5 mm thick blades. In contrast, aluminum alloy 7075 without nano-treating failed to produce good casting quality due to poor filling and severe cracks. The manufacturing trials highlight the significant improvement in castability achieved through nano-treating, opening a novel pathway for the cost-effective production of complex aluminum alloy 7075 structures for numerous applications.

Nanotechnology-enabled rapid investment casting of high-performance wrought aluminum alloys

High-performance wrought aluminium alloys are widely used in automobiles and aerospace industries owing to their high-volume precipitates after heat treatment. Investment casting as one of the precision manufacturing methods provides great potential to achieve excellent surface finishes and complex geometry for aluminium alloy components. However, these high-performance aluminium alloys are almost impossible to be investment cast due to their hot cracking susceptibility and severe shrinkage during solidification. In this study, we introduce nanotechnology to improve the processability of high-performance wrought aluminium alloys in investment casting by adding a small volume fraction of nanoparticles into the aluminium alloys. This work showed the unprecedented success of nanotechnology-enabled investment casting of high-strength wrought aluminium alloys (AA6061, AA2024, and AA7075) for excellent mechanical properties.

Experimental Performance Evaluation of a Lightweight Additively Manufactured Hydrodynamic Thrust Bearing

In this paper, a lightweight additively manufactured (AM) fixed geometry hydrodynamic thrust bearing fabricated via laser powder bed fusion (LPBF) is experimentally compared to a traditionally manufactured cast aluminum alloy thrust bearing of similar design. The purpose of this study is to evaluate how weight-saving design features in the AM bearing affect active critical hydrodynamic performance parameters to better understand in-service viability. Under various static operating conditions, performance parameters such as hydrodynamic pressure distribution, minimum oil film thickness (MOFT), bearing temperature and increase in oil temperature are measured. Compared to the traditionally manufactured bearing, the AM bearing showed an average increase in minimum oil film thickness of 53%, an average increase in trailing edge hydrodynamic pressure of 116%, while exhibiting an average decrease in bearing temperature of 1%. Experimental results are compared to numerical simulation showing reasonably good agreement.

Rapid investment casting of nano-treated aluminum alloy 2024

Rapid investment casting of nano-treated aluminum alloy 2024