As-cast Aluminum Research Articles

Investigating the Impact of Robotic Milling Parameters on the Surface Roughness of Al-Alloy Fabricated by Wire Arc Additive Manufacturing

This paper takes the single-wall wall manufactured by wire arc additive manufacturing (WAAM) as the research object and compares it with the as-cast aluminum alloy with the same series. By using feed rate, cutting depth, spindle speed, etc., as single or compound parameters, the machinability of the sample is analyzed. The results indicate that the influence of varying parameters on the as-deposited aluminum alloy follows the order of feed rate > cutting depth > spindle speed. As the feed rate increases, the surface roughness initially decreases and then increases, with the optimal surface quality achieved at 12 mm/s (with a surface roughness of 2.013 μm). Different from the as-deposited alloy, the influence of the parameters on the as-cast alloys follows the order of spindle speed > cutting depth > feed rate. The experiments reveal that, for both as-deposited and as-cast states, the trends of the impact of cutting depth and spindle speed on surface quality are consistent. However, at low feed rates (2–12 mm/s), for as-deposited states, the surface quality of as-deposited samples becomes smoother as the feed rate increases (contrary to common knowledge). This result can be attributed to the elevated milling temperature, which softens the material, making it easier to remove and reducing the surface roughness.

Development, modelling and optimization of process parameters on the tensile strength of aluminum, reinforced with pumice and carbonated coal hybrid composites for brake disc application

This study focuses on optimizing double stir casting process parameters to enhance the tensile strength of hybrid composites comprising aluminum alloy, brown pumice, and coal ash, intended for brake disc applications. Analytical techniques including X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were employed to characterize the composite constituents. The Taguchi method was utilized for experimental design and optimization to determine the optimal weight compositions of brown pumice and coal ash, as well as stir casting parameters (stirrer speed, pouring temperature, and stirring duration). Regression analysis was employed to develop a predictive mathematical model for the tensile strength of the hybrid composites and to assess the significance of process parameters. The optimized composite achieved a predicted tensile strength of 186.81 MPa and an experimental strength of 190.67 MPa using 7.5 vol% brown pumice, 2.5 vol% coal ash, a pouring temperature of 700 °C, stirrer speed of 500 rpm, and stirring duration of 10 min. This represents a 52.23% improvement over the as-cast aluminum alloy’s tensile strength. Characterization results revealed that brown pumice and coal ash contain robust minerals (SiO2, Fe2O3, Al2O3) suitable for reinforcing metal matrices like aluminum, titanium, and magnesium. Thermogravimetric and differential thermal analyses demonstrated thermal stability up to 614.01 °C for the optimized composite, making it suitable for brake disc applications.

Role of oscillation frequency and amplitude on the microstructure and properties of linear friction welded nickel aluminium bronze joints

This study explores the influence of oscillation frequency and amplitude on the quality of linear friction welded joints using as-cast nickel aluminium bronze. Welding was conducted at 30 Hz, 50 Hz, and 70 Hz oscillated frequencies and amplitudes of 1.5 mm, 2 mm, and 3 mm. The joint’s performance was thoroughly investigated through systematic analysis, including macrostructure examination, peak interfacial temperature measurement, microstructure evaluation, strain assessment, cooling rate determination, microhardness testing, and tensile property characterization. The width of the weld zone varied from 183 μm to 297 μm, and the thermomechanical affected zone (TMAZ) area ranged from 4.48 mm2 to 14.79 mm2 across different process parameters. In the parent material, the volume fraction of the β-phase was as low as 20.2%, contrasting with the dominant α-phase at 79.8%. The average grain size of the lamellar and globular α-phase mixture was 26.4 μm. Notably, the weld zone exhibited extremely refined α-phase grains, with diameters less than 5 μm in all cases. The volume fraction of the β‘-phase increased significantly with higher frequencies, from 15.299% at 30 Hz to 26.98% at 50 Hz, peaking at 40.08% at 70 Hz, leading to varying k phases. This variation in microstructure had a substantial impact on mechanical properties. Tensile strength ranged from 503 MPa to 582 MPa, while ductility varied from 13.5% to 21.7%. Additionally, the hardness of the parent material increased from approximately 155 Hv to 260 Hv. This study demonstrates that controlling the oscillation frequency and amplitude in linear friction welding processes can yield consistent, high-quality welds in nickel aluminium bronze.

Solute micro-segregation profile and associated precipitation in cast Al-Mg-Si alloy

ABSTRACT The micro-segregation in the as-cast AA6082 aluminium alloy were investigated across a range of length scales using a combination of analytical electron microscopes. It is found that the micro-segregation bands form an inter-connected network following grain boundaries and inter-dendritic channels. The micro-segregation can be divided into major micro-segregation and minor micro-segregation; the former is mainly on the grain boundaries consisting of iron-bearing intermetallic; the latter occurs both, along the grain boundaries and inter-dendritic channels, consisting mainly of Mg and Si alloying elements. The atomic-scale imaging reveals that in the minor-segregation bands, the supersaturated solute concertation has formed precipitates that had either nucleated heterogeneously on the dislocation network or homogeneously inside the aluminium matrix. The heterogeneously nucleated precipitates in the dislocation lines are composed of a mixture of phases down the precipitation sequence meanwhile, the homogenously grown ones are discrete phases that appear at the early stages of the precipitation sequence.

Effect of Sc on Al3Fe phase and mechanical properties of as-cast AA5052 aluminum alloy

Effect of Sc on Al3Fe phase and mechanical properties of as-cast AA5052 aluminum alloy

Effect of Solution Concentration and Anodizing Coating Time on Hardness and Thickness Coating Of 7075-O Aluminum Alloy

One of the materials used in ship propellers is aluminum alloy. The advantages of aluminum are that it is easy to cast and relatively resistant to corrosion. This research aims to determine the effect of heat treatment and the effect of variations in the concentration of H2SO4 and immersion time in optimal of the anodizing process on the hardness value of 7075-O aluminum alloy (as-cast aluminum alloy). The method used is solution heat treatment at a temperature of 490ºC with a holding time of 6 hours, quenching using water or oil, with artificial aging at a temperature of 120ºC with a holding time of 24 hours. In the anodizing process, a sulfuric acid solution with various concentrations of 10%, 15%, and 20% with variations in immersion time of 10, 15, and 20 minutes. The results of vickers hardness test on heat-treated specimens with water quenching accompanied by artificial aging is 137.54 HV, it is increased by 47.44%. While the results of the vickers hardness test after anodizing is 213.09 HV, it is increased by 128.42%. Where the optimum hardness value was achieved at a concentration of 15% H2SO4 and an immersion time of 20 minutes. The coating thickness is equal to 25.79 µm.

Remelting of Aluminum Scrap Into Billets Using Direct Chill Casting

An as-cast aluminum billet with a diameter of 100 mm has been successfully prepared from aluminum scrap by using direct chill (DC) casting method. This study aims to investigate the microstructure and mechanical properties of such as-cast billets. Four locations along a cross-section of the as-cast billet radius were evaluated. The results show that the structures of the as-cast billet are a thin layer of coarse columnar grains at the solidified shell, feathery grains at the half radius of the billet, and coarse equiaxed grains at the billet center. The grain size tends to decrease from the center to the surface of the as-cast billet. The ultimate tensile strength (UTS) and the hardness values obtained from this research slightly increase from the center to the surface of the as-cast billet. The distribution of Mg, Fe, and Si elements over the cross-section of the as-cast billet is inhomogeneous. The segregation analysis shows that Si has negative segregation towards the surface, positive segregation at the middle, and negative segregation at the center of the as-cast billet. On the other hand, the Mg element is distributed uniformly in small quantities in the cross-section of the as-cast billet.

The effect of friction stir-back extrusion speed on Al-Cu-Mg-Li alloy microstructure and corrosion behaviour

ABSTRACT In this study, the effect of extrusion speed on the microstructure and corrosion behaviour of a friction stir-back extruded Al-Cu-Mg alloy containing 0.5 wt.% Li was investigated. Results show that friction stir-back extrusion on an as-cast aluminum alloy with a dendritic microstructure forming finely equiaxed recrystallized grains. With decreasing extrusion speed from 80 to 40 mm/min, the average grain size increases from 6.0 ± 1.2–9.8 ± 3.2 µm. After friction stir-back extrusion, the morphology of the Cu-Mg-rich precipitates has completely changed, and the fine precipitates (0.25-0.42 µm) with a uniform distribution have formed in the microstructure of the extruded wires. With the reduction of the extrusion speed from 80 to 40 mm/min, the accumulated strain in the extruded wires increases from 0.006-0.011. Compared to as-cast alloy, friction stir-back extrusion results in at least 23, 37, and 22% increases in yield strength, tensile strength, and elongation. The minimum corrosion current (1.32 × 10−4 A.cm−2) and corrosion rate (0.003 mm/year) were achieved in the wire extruded at a rotational speed of 800 rpm and an extrusion speed of 60 mm/min.

Friction stir extrusion and mechanical alloying of LM13 casting ingot to produce LM28 tubes

Friction Stir Extrusion (FSE) is applied on the as-cast LM13 aluminum alloy to produce tubes accompanied with the microstructural modification. Then, the process was employed to transform LM13 to LM28 alloy by mechanical alloying by adding Si particles during the process. In addition, a numerical model on the Deform 3D software is developed to simulate the process and investigate the temperature and strain distributions at different zones as well as the material flow over the process. The experimental and numerical results show that the peak temperature and strain of 460 °C and 200 are attained in the zone 6–10 mm after the conical part finish, where the material completely enters the tube channel. The temperature and strain distributions were varying through the tube wall, and the result is that the average Si precipitates’ size in the wall inside reduced to almost 0.8 μm while is 2 μm at the center of the tube wall. Furthermore, the material flow from the primary cylindrical ingot towards the tube wall was not uniform in the sample cross-section due to tool design, and the velocity of material movement at various zones was different. Mechanical alloying of LM13 alloy, by the addition of Si particles in ∼6 %, transformed the alloy to LM28 by increasing the silicon content from 12.2 to 19.2 %. The ultimate compression strength of the LM13 base metal increased from 84.7 to 138.7 MPa and 158.2 MPa, respectively, for LM13 and LM28 by breakage of needle-like Si precipitates and fine dispersion of them in the aluminum substrate.

An experimental investigation of the effects of radiation and thermal parameters on the aluminum 1050 obtained from upward directional solidification

During the reactor operation, aluminum tank and the core components can experience radiation damage, resulting in limitation of its life span. Effects of radiation on the aluminum alloys are not yet fully understood, especially when material is obtained from upward directional solidification under transient heat-flow condition. For this paper, an experimental research has been conducted to investigate the radiation effects on the as-cast aluminum 1050, with focus on the microstructure, microhardness and porosity for different position along casting. Firstly, thermal parameters were determined during solidification experiment and then correlated with cellular spacings, microhardness and porosity content. The experimental results show that thermal parameters such as solidification speed, thermal gradient and cooling rate exerts an influence on the microstructure, microhardness and porosity. Experimental laws for microstructure, microhardness and porosity have been determined, indicating that the increase in thermal parameters has induced a refinement effect on the microstructure, increase in microhardness and a decrease in the porosity content. Further, measurable effects of the gamma radiation on the microstructure, microhardness and porosity formation along the ingot of aluminum 1050, were experimentally determined. It stands out among results that gamma radiation has favored an increase in cellular spacings, microhardness and porosity in ingot, obtained from a vertical upward directional solidification. However, even after the gamma radiation exposure, microstructure, microhardness and porosity found along the casting are dependent of the solidification thermal conditions.

Determination of Optimal Modifier Level for Eutectic Silicon Phase in Hypoeutectic AlSi7Mg0.3Cu0.5 Cast Alloy

Silicon particles in as-cast aluminum alloys can be modified using various modifiers, with Strontium (Sr) and Sodium (Na) being the most employed in the aluminum casting sector. However, their concentration diminishes (fades) during the melting furnace process. Modifier fading within the melt can result from three principal chemical reactions: vaporization of the modifier under high vapor pressure conditions at melting temperatures, oxidation driven by a significant affinity for oxygen, or interaction with other elements in the melt leading to the formation of intermetallic compounds. Given the very low vapor pressure of both Na and Sr, their vaporization from the aluminum melt was excluded as a reason for the modifier's fading. Oxidation seems to be like the primary chemical reaction leading to the fading of Na and Sr from the aluminum melt. This study examined the effect of Sr and Na fading on the modification level of silicon particles in the AlSi7Mg0.3Cu0.5 (356) aluminum alloy. The cooling curve analysis has been utilized to quantify modifier fading. Approximately 105 ppm of Sr in the form of master alloy (AlSr10) and 67 ppm of Na in the tablet form were separately added to the melt. Both modifiers were kept in the melt for approximately 200 minutes to monitor their fading. The present paper aimed to quantify the fading of Na and Sr in an AlSi7Mg0.3Cu0.5 alloy. The depletion of modifiers (Na and Sr) while the melt is retained in a furnace can be quantitatively determined through equations derived from existing literature. The surface reaction rate constant (ks), once calculated, serves as a tool for predicting the extent of modifier loss during the melt-holding process in both industrial and laboratory furnaces.

Effect of water temperature and induced acoustic pressure on cavitation erosion behaviour of aluminium alloys

Cavitation erosion is a major challenge for marine and fluid machinery systems. This study investigated the erosion performance of two as-cast aluminium alloys exposed to acoustic cavitation in water at temperatures of 10–50 °C and those were then compared with an extruded wrought alloy tested specifically at the temperature of maximum erosion. The results showed that the as-cast A380 alloy displayed exceptional resistance to cavitation erosion, with the lowest mass loss and surface roughness. This finding suggests that the as-cast A380 alloy is a suitable choice for lightweight, high-performance components in applications where cavitation resistance is critical.

The Characterization of Coatings Formed on As-Cast Al, Al–Si, and Al–Ca Aluminum Substrates by Plasma Electrolytic Oxidation

In this study, ceramic coatings were grown on the surface of as-cast aluminum alloys via plasma electrolytic oxidation (PEO). The effect of the Si- and Ca-alloying elements in aluminum on the growth process, morphology, composition, mechanical, and corrosion properties of the PEO coatings was investigated. Uniform coatings with a minimum number of defects were formed on the surfaces of Al–Ca alloys. Increasing the Si content in Al led to an increase in the bulk and surface porosity of the coatings. The α-Al2O3 phase mainly formed in the coatings synthesized on pure Al and Al–Ca alloys, while an increased amount of Si in Al alloys hindered the formation of the α-Al2O3 phase. The coatings had a microhardness of 660–1180 HV, which was 20–30 times higher than that of the original as-cast alloy. Moreover, the coating on the Al–Ca alloys had the highest peak hardness, which was probably caused by the formation of a greater amount of the α-Al2O3 phase. Electrochemical studies in 3.5% NaCl have shown that PEO coatings reduce the corrosion current density. Of all PEO-treated alloys, Al and Al1Ca have the lowest corrosion current density and hence the highest corrosion resistance due to the composition and uniformity of the coating.

The effect of rolling temperature on the microstructure and properties of multi pass rolled 7A04 aluminum alloy

The current research on 7-series aluminum alloys mainly focuses on solid solution and aging treatments, as well as the flow stress during the deformation process. There are limited researches on the influence of thermal deformation temperature on the microstructure and properties of the aluminum alloy during multi-pass hot rolling process. In this study, the as-cast 7A04 aluminum alloy was subjected to homogenization treatment, followed by multi-pass hot rolling. The effects of different deformation parameters on dislocation density were analyzed. Microstructural characterization of the deformed alloy was performed using optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and micro-hardness tester. The optimal microstructure of the deformed alloy was selected based on the size of recrystallization. Subsequently, the Deform–3D finite element simulation software was used to analyze the multi-pass hot rolling process. The influence of deformation parameters on the uniformity of equivalent strain distribution within the samples was investigated. The results showed that at the deformation temperature of 430 °C, a significant amount of recrystallized microstructure appeared in the alloy, resulting in the lowest dislocation density and a significant reduction in the quantity of coarse precipitates. Finite element numerical simulation revealed that the deformation temperature had a certain influence on the uniformity of strain distribution within the alloy. However, this influence was mostly eliminated when the deformation temperature exceeded 380 °C. Meanwhile, the distribution of strain within the alloy was found to be related to the temperature distribution.

Microstructure evolution and constitutive modeling of as-cast A356 aluminum alloy in semi-solid deformation regime

The present work deals with the semi-solid deformation behavior of A356 aluminum alloys with an emphasis on microstructure evolution and constitutive modeling. The main idea of this research is based on investigating the semi-solid deformation behavior starting with primary dendritic cast structure, instead the conventional approach in which a feedstock is prepared through the various spheroidization process. Toward this end, hot compression tests in the semi-solid temperature range (580, 590, and 600 °C) under different strain rates (0.001, 0.01, 0.1 s−1) and different initial holding times (1, 7, and 14 min) have been conducted. Compared with the thixotropic deformation in which the solid globules slide within the liquid matrix through lubricated flow mechanisms, in the present case, the strain compensation through the deformation of solid grains was increased. The higher portion of the solid-grains from the applied strain provided a proper condition for substructure development and dynamic recrystallization in the semisolid temperature range. The penetration of the liquid phase along the newly developed boundaries was introduced as another factor influencing on the softening behavior of the material. Under these conditions, the specimens were deformed up to the high strain level (>0.5) without creating cracks or tearing under very low stresses less than 2 MPa. A phenomenological-physical constitutive equation was also developed considering deformation parameters (temperature, strain rate, and strain) and material's parameters (grain size, strain rate sensitivity, viscosity) which was capable of predicting the semisolid flow stress behavior of the material.

Primary phase transformation mechanism in a hypereutectic Al-Ce alloy during rapid solidification

Cooling rate plays an important role in determining the microstructure in as-cast aluminum alloys. To obtain a cooling rate gradient, a wedge Cu mould was selected. Here, we found a transition from hypereutectic to hypoeutectic microstructures in a hypereutectic Al-Ce alloy during rapid solidification. There was a distinct interface at a cooling rate of 1598 K/s. When the cooling rate was lower than 1598 K/s, the microstructures were composed of primary Al11Ce3 phases and Al/Al11Ce3 eutectic colonies. As the cooling rate was higher than 1598 K/s, the primary Al11Ce3 phases transformed into α-Al. Compared with the α-Al, the nucleation of Al11Ce3 phases was more favorable because of the lower nucleation energy. The growth rate of α-Al was higher than that of Al11Ce3 phases as the undercooling was larger than 182 K. Primary phase transformation mechanism in the hypereutectic Al-Ce alloy was controlled by nucleation and growth of α-Al and Al11Ce3 phases.

Ultrasonic melt processing upon direct-chill casting of aluminium alloys

Ultrasonic melt processing (USP) has been known for decades for beneficial effects in as-cast aluminium alloys, including degassing, grain and structure refinement. In the last 10 years the authors performed a series of research projects dedicated to understanding the nature of these effects, by dedicated advanced experiments and by developing numerical models that adequately reflect the complicated physics involved, aiming at further optimising the technology so that it becomes feasible for scale-up applications and attractive for industrial use. Based on the main USP mechanisms previously studied by in-situ observations coupled with acoustic pressure measurements, i.e. fragmentation, deagglomeration and dispersion of the solid phases and inclusions, technological approaches are suggested and tested for grain refinement upon direct-chill casting of Al alloys. Results showed that USP in the melt flow in the launder significantly improves the as-cast structure of a billet, opening the way for upscaling.

Artificial neural network approach for mechanical properties prediction of as-cast A380 aluminum alloy

In this study, the dataset of as-cast A380 aluminum alloy involving chemical composition, processing parameter and mechanical properties was experimentally established. On this basis, the relationship between four input variables of Fe/Mn ratio, Sr content, cooling rate and porosity content, and two outputs of ultimate tensile strength (UTS) and elongation (El) was linked by two artificial neural network (ANN) models for comparison: (1) back propagation - artificial neural network (BP-ANN) model, and (2) back propagation optimized by particle swarm optimization - artificial neural network (PSO-BP-ANN) model. The results showed that the established PSO-BP-ANN model has better reliability and prediction accuracy than BP-ANN model, for lower root mean square errors (RMSE), 6.19 MPa for UTS and 0.08% for El, and higher determination coefficient (R2), 0.9775 for UTS and 0.9798 for El, respectively. Sensitivity level analysis result by the preferable PSO-BP-ANN prediction model showed that the order of relative importance for UTS is Sr content, cooling rate, Fe/Mn ratio, and porosity content while the importance ranking for El is Sr content, Fe/Mn ratio, cooling rate, and porosity content. The research results and dataset in this work lay a foundation for the control of casting performance in industrial practice and for secondary development of mechanical properties prediction module in commercial casting software.

Reliability and properties enhancement of as-cast aluminum alloy through gating system design

In this work, the influence of temperature on fluidity and gating system design on the physical, and mechanical properties of as-cast AA6063-T6 aluminum alloy have been examined. The pouring temperature has been used as a controlling parameter for flowability measurement and a spiral ceramic placed in a sand mold for measuring the fluidity index of the molten alloy. A linear relationship between the casting temperature and the fluidity length was observed. These show that fluidity increases linearly with the pouring temperature. Also, an expanding systems and pressurized gating systems were experimented through sprue-runner to cross-sectional area variation. The ultimate tensile strength of the samples was not significantly affected by the in-gate system design. Meanwhile, the fracture elongation seemed to be more dependent on the melt quality than on the in-gate system design. The true stress-strain graph indicates that expanding systems are better than pressurized systems. The plot of residual against fit for regression analysis does not show random distribution about the reference point.

Artificial Neural Network Approach for Mechanical Properties Prediction of As-Cast A380 Aluminum Alloy

Artificial Neural Network Approach for Mechanical Properties Prediction of As-Cast A380 Aluminum Alloy