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Alloy wheels must meet rigorous durability and safety tests to meet structural demand during use. The use of aluminum (Al) alloyed with silicon (Si) stands out due to the good relationship between density and strength and also its esthetic appeal, which is made possible by the suitable alloy machinability. The use of A356 alloy processed through low-pressure die casting and T6 heat treatment comes from the need for suitable mechanical properties and ease of large-scale cyclic processing. The wheel sector's high competitiveness demands accelerated development with less time-to-market and better performance. The use of numerical cast simulations helps predict the thermal and microstructural parameters of the alloy resulting from the solidification process inside a metallic mold. Understanding the solidification thermal parameters is of great importance for predicting either the phase morphologies or the dendritic length-scale of the casting, since these features have a direct impact on the alloy's strength. The present study aims to develop a computational simulation tool using commercial casting software to predict the tensile properties of as-cast and heat-treated automotive wheels. To achieve this objective, directional solidification (DS) experiments with the A356 alloy were carried out in order to determine equations relating the solidification time and cooling rate along the casting. The generated casting by the DS was further divided into parts, heat-treated and untreated, and each half part was examined for both tensile testing and the determination of secondary dendrite arm spacing (λ2). This allowed the development of key experimental equations relating λ2 with solidification time and tensile properties with λ2. In the end, a coupled simulation tool underwent testing using real tensile test data from wheels before and after T6 treatment. This testing involved two methods of correlating tensile properties with λ2: Hall-Petch-type (HP) and Ludvig model approaches. The HP model more accurately represents the strength data from various wheel regions, with a small average error of approximately 5.6% for ultimate strength. [ABSTRACT FROM AUTHOR]

This study explores the development of a novel side core design with an integrated cooling system for the low-pressure die casting (LPDC) of A356 aluminum alloy wheel rims in Indonesia. The objective is to reduce cycle time and minimize casting defects. The methodology involves 3D modeling using SolidWorks and simulations performed with MAGMAsoft to evaluate filling and solidification behavior, air pressure, and air entrapment. Notably, this is the first application of a cooling system in Side cores within the Indonesian automotive industry, motivated by the need to improve production efficiency and product quality, as current manufacturing processes suffer from long cycle times and high defect rates. Simulation results show a significant reduction in cycle time by 72 seconds, improving both efficiency and product quality. This study demonstrates the effectiveness of integrating cooling systems into side cores to enhance the LPDC process.

This article aims to study the metallurgical and mechanical changes that occurred due to the T6 heat treatment of SiC particle-reinforced A356 matrix composite. The stir-casting technique was used for the fabrication of the composite. The fabricated composite was T6 heat-treated. Along with Mg2Si, MgAl2O4 a new phase, MgO was identified through energy dispersive X-ray spectroscopy mapping. An improvement in the mechanical properties was observed. All the mechanical properties are not equally influenced by T6 heat treatment. The formed phases act as strong obstacles to the slip and dislocation of the matrix which improves the ultimate tensile strength value by 40–42%, and impact strength 3 times higher than that of unheat-treated composite but only 10–12% improvement in hardness. [ABSTRACT FROM AUTHOR]

In the present work, the effects of Zr and/or Y addition on microstructure and mechanical properties of cast A356 alloy were investigated using X-ray diffractometer (XRD), differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The heterogeneous nucleation effect on Zr-rich phases generated by the peritectic reaction, the increased constitutional undercooling caused by Y addition and serve as surfactant led to the grain refinement. Besides, The average size of eutectic Si reduced from 8.5 μm in the base alloy to 6.2, 1.3, and 1.7 μm with the addition of Zr/Y/Zr + Y, respectively. Zr can slightly refine eutectic Si due to the limited growth space caused by grain refinement, while Y can modify the morphology of eutectic Si from plate-like into fibrous-like through high density twins formed by the IIT mechanism. The optimal mechanical properties are obtained when Zr and Y are added simultaneously with the ultimate tensile strength, yield strength, and elongation values of 104 MPa, 201 MPa, and 7.6%, respectively. The YS and UTS increase was due to grain-refining, Si modification and precipitation strengthening. The enhancement of El was mainly caused by Si modification, which reduced the possibility of crack initiation and propagation at Si/α-Al interfaces.

The challenges commonly associated with conventional high pressure die casting (HPDC) have led to increased interest in semi-solid metal (SSM) forming processes. In the present study, semi-solid slurries of A356 alloy prepared by the Swirled Enthalpy Equilibration Device (SEED) process were used for manufacturing components with complex shape by using a high pressure die casting machine. The segregation phenomenon and the effect of heat treatment on the microstructure evolution and mechanical properties were investigated. The results showed that the alloy consists of primary spherical α-Al grains, secondary solidified α-Al grains, eutectic Si, iron-rich intermetallic phases and low porosities. The microstructural investigations revealed that the eutectic Si particles underwent fragmentation, spheroidization and coarsening with increasing solution temperature. Furthermore, the solution treatment results in the dissolution of the π-Al8FeMg3Si6 phase and the growth of the β-Al5FeSi phase. The hardening peaks at 170 °C could be obtained with ageing for 5 h. Due to both solution and precipitation strengthenings, the yield strength, ultimate tensile strength and hardness of A356 alloy after heat treatment increase significantly compared to those in the as-rheocast state: they reach 266 MPa, 343 MPa and 110 HV0.2, respectively. The analysis of fracture surfaces of rheo-HPDC samples in both the as-rheocast and the heat-treated states revealed a mixed mechanism of dimples and quasi-cleavage. The microstructure inside the part was found to be quasi-homogeneous while the segregation phenomenon in different zones of the part is affected by die geometry during the filling process. The results imply that the SEED-HPDC process has the potential to be industrialized by implementing appropriate heat treatments for producing complex components with good mechanical properties.

Manufacturing by casting method in aluminum and its alloys is preferred by different industries today. It may be necessary to improve the mechanical properties of the materials according to different industries and different strength requirements. The mechanical properties of metal alloys are directly related to the microstructure grain sizes. Therefore, many grain reduction methods are used during production or heat treatment. In this study, A356 alloys were molded into molds at 750 °C and exposed to vibration frequency at 0, 8.33, 16.66, 25, and 33.33 Hz during solidification. Optical microscopes images were analyzed in image analysis programs to measure the grain sizes of the samples that solidified after solidification. In addition, microhardness tests of samples were carried out to examine the effect of vibration and grain reduction on mechanical behavior. In the analyzes made, it was determined that the grain sizes decreased from 54.984 to 26.958 µm and the hardness values increased from 60.48 to 126.94 HV with increasing vibration frequency. [ABSTRACT FROM AUTHOR]

The comparative analysis of the two hybrid composites, obtained by the compocasting process, based on A356 and ZA-27 alloys and reinforced with 10 wt. % SiC and 0, 1 and 3 wt. % graphite (Gr) is presented. Optimisation of their tribological behaviour was performed by the Taguchi method and the artificial neural network (ANN). Tribological tests were performed on a block-on-disk tribometer, at three sliding speeds, three normal loads and a sliding distance of 600m, without lubrication. Results obtained by the ANOVA showed that the hybrid composites based on A356 alloy have the better wear resistance and that the composite reinforced with 10 wt. % SiC and 1 wt. % Gr has the lowest wear rate. The lowest coefficient of friction was obtained for a composite based on ZA-27 alloy reinforced with 10 wt. % SiC, at a normal load of 10 N and sliding speed of 1 m/s. [ABSTRACT FROM AUTHOR]

The Indian foundry industries are facing problems to produce the casting at a lower cost due to an increase in the cost of the raw materials. On the other hand, the use of Fe–Cr slag as a mold material in foundry industries was not explored. Therefore, the present investigation was focused on the designing and optimization of Fe–Cr slag mold's constituents for Al-alloy (A356) castings. The optimum properties of the Fe–Cr mold such as mold hardness number, permeability number, compressive, and shear strength were found to be 87, 158, 1.45 kg/cm2, and 0.38 kg/cm2, respectively. Aluminum alloy (A356) castings were made from Fe–Cr slag and silica sand mold. It was observed that Fe–Cr slag mold casting has good dimensional stability in comparison to silica sand mold casting. The Brinell hardness and microstructure of the castings were evaluated and a possible structure-property relationship was explained. It was observed that Fe–Cr slag has a lot of potentials to be used as an alternative to silica sand mold for Al-alloy castings. However, its recyclability, production of required particle size of Fe–Cr slag using atomization, and its cost need to be studied before recommending its use in Indian foundry industries. [ABSTRACT FROM AUTHOR]

Mechanical properties of the castings are directly affected negatively by the inclusions, such as its own oxide occurring during melting, if proper and logical liquid metal processes could not be carried out. To overcome this issue, different compositions and types of fluxes were practiced. Na2SiF6, NaF/AlF3 (cryolite ratio) = 1.85, 2.8, and 3, NaF, Na3AlF6 (commercial cryolite) added with different ratios to the mixture of NaCl+KCl, and also only Na2SiF6 to the mixture of MgCl2+KCl were appended to the liquid metal to remove inclusions, such as old oxide bifilms. Average effectiveness values of the fluxes concerning mechanical properties were investigated as well. The change in the melt cleanliness before and after degassing has been taken into account to establish a model that correlates bifilm index and tensile properties. Since bifilm index is directly interested in porosity shape and amount to quantify liquid metal quality, any other techniques, such as density index, were not be consulted. In addition, the main focus was based on how much the melt was cleaned rather than the cleanliness of the melt after degassing. Thus, the difference of bifilm index as a melt cleanliness indicator firstly was introduced to the literature. In addition to this, the contour plots of mechanical properties and bifilm index values were used to evaluate the correlation, and it was found that there was an exponential relationship, a quality index, between elongation at fracture, tensile strength, and bifilm index. [ABSTRACT FROM AUTHOR]

The present investigation was focused on designing and developing Narmada riverbed sand (NRS) as an alternative to commercial-grade silica sand (CGSS) for the green sand mold casting process. The green NRS mold constituents were modeled and optimized through response surface methodology (RSM) to achieve the mold's desired physical and mechanical properties. The RSM model predicted the optimum constituents of NRS mold and found it to be 4.4 wt% moisture, 11.7 wt% bentonite, and 3.9 wt% coal dust to achieve the desired mold properties. The properties of NRS mold, such as mold hardness, permeability number, compressive strength, and shear strength, were found to be 88, 209, 1.6 kg/cm2 (0.156 MPa), and 0.38 kg/cm2 (0.037 MPa), respectively. A laboratory trial of aluminum-silicon alloy (A356) cuboid casting was conducted using green NRS and CGSS mold. The as-cast dimensions, surface roughness, hardness, and microstructure were evaluated and compared. It is observed that the NRS mold is suitable for A356 alloy casting. However, the recyclability of Narmada riverbed sand may be studied further to understand its commercial use as an alternative material to CGSS for non-ferrous alloy casting in Indian foundries. [ABSTRACT FROM AUTHOR]

In order to obtain the optimal parameters for thixoforging of A356 aluminum alloy parts, the effects of heating temperature and holding time on the microstructure and mechanical properties of the formed parts with or without T6 heat treatment obtained via thixoforging hot-deformation A356 aluminum alloy directly heated to semi-solid temperature were investigated. Microstructure results showed that lower temperature and shorter holding time refined the grains. The tensile tests results showed that optimal parameters for thixoforging of A356 were heating temperature of 590 °C and holding time of 1 min. TEM results showed that needle-like β" aging precipitated particles with a size of 5 × 5 × 50 nm and equiaxed silicon particles of 50 nm were uniformly distributed in the matrix after T6 heat treatment, which were the strengthening phases of A356 alloy. The needle-like β" phases were parallel to the < 001 > crystal orientation of the matrix. The strengthening phase precipitated by aging increased the yield strength and tensile strength and decreased the elongation. The thixoforging parts under optimal parameters exhibited a yield strength of 291.3 MPa, the tensile strength of 324.9 MPa and the elongation of 10.2% after standard T6 heat treatment. [ABSTRACT FROM AUTHOR]

In this paper is presented the tribological behavior of A356-based aluminum composites using Taguchi design. Testing of tribological characteristics of aluminum composites was done on a tribometer with block on disc contact geometry. Composite materials were obtained by compocasting. The orthogonal matrix L18 is used to form the experimental design using the Taguchi method. The tribological characteristics of the aluminum composite reinforced with SiC (A356/10 wt.% SiC) were compared to the base material A356 for three sliding speeds (0.25 m/s; 0.5 m/s and 1.0 m/s), three values of normal load (10 N, 20 N and 30 N) and sliding distance of 150 m under lubrication conditions. ANOVA analysis showed that the least wear has a composite material at a load of 10 N and at sliding speed of 0.25 m/s.

The automobile industry has been concentrating on developing eco-friendly materials that improve the safety and fuel efficiency of automobiles. Aluminum alloys, well known as lightweight materials, have been studied, particularly as the demand for high-strength and lightweight materials has been increasing. This study focuses on the technique of rheocasting using electromagnetic stirring (EMS), which is a typical semi-solid method for manufacturing aluminum products. Focusing on EMS, the effect of current input methods on the castability, roundness, and mechanical properties of products manufactured by rheocasting was evaluated. A large electromagnet was used to stir the molten metal, with a maximum weight of 5 to 20 kg of molten metal used in industry, using two types of current input methods—direct current (DC) and alternating current (AC). The microstructure, roundness, and mechanical properties were evaluated by fabricating a tensile specimen using EMS experimentation. The experimental results showed that excellent castability appeared at solid fractions of 20 and 30%. In addition, when the products were manufactured with a solid fraction of 20% and an AC input, the apparent tensile strength was the highest at 177 MPa. The equivalent diameter of the α-Al particles was 53 μm and the roundness was 1.8. [ABSTRACT FROM AUTHOR]

In this research, Cr3C2-NiCr and WC-Co-Cr cermet coatings were developed on A356 aluminum-based alloy substrate by the high-velocity oxy-fuel (HVOF) technique for use in wear and corrosion applications. The substrate and coatings were characterized using a field emission scanning electron microscope (FESEM) equipped with the energy dispersive spectroscope (EDS), microhardness, wear, and corrosion test instruments. Microstructural observations revealed that the coatings with an average thickness of about 250 μm were well bonded with the substrate. The microhardness of the Cr3C2-NiCr (~930 HV) and WC-Co-Cr (~1300 HV) coatings were about eleven and sixteen times higher than that of the A356 substrate (~80 HV), respectively. Cermet coatings showed significantly lower mass losses, wear rates, and friction coefficients in comparison with the A356 substrate. WC-Co-Cr coating illustrated higher tribological performance in comparison with Cr3C2-NiCr coating. The mass loss and friction coefficient of the WC-Co-Cr coating under an applied load of 10 N was about 0.2 mg and 0.13 (about 99.5% and 79.7% lower than that of the A356 substrate, e.g., 41.5 mg and 0.64), respectively. Rising applied load increased the wear characteristics of the A356 substrate with the more pronounced degrees. FESEM observations on wear test specimens illustrated the different wear mechanisms on the surfaces. The results illustrated significant improvements in the corrosion performances of the coated samples. [ABSTRACT FROM AUTHOR]

The paper discusses the response to free vibration and also to forced vibration of the A356-SiC AMMCs in the as-cast and T6 temper conditions for the comparative assessment of the damping capacities. The base A356 aluminium alloy and seven A356-SiC composites with SiC percentage ranging from 2% to 12% were stir cast and cantilever specimens of 180 mm length were tested for their frequency and amplitude responses. From the results obtained, it was concluded that the A356-SiC composites with 8% SiC and 3% SiC in the T6 condition could be favourably considered as candidate materials for diesel engine parts in the automotive industry. [ABSTRACT FROM AUTHOR]

The present investigation focuses on the development of metal casting mold using stone-dust as an alternative mold material to silica sand. The stone-dust aggregate mold having 4 wt.% of moisture and 11 wt.% of bentonite clay shows desired mold properties as per AFS standard. The mold properties such as permeability number, hardness (B-scale), compressive, and shear strength are 147, 88, 1.48, and 0.33 kgf/cm2, respectively. The fusion point of stone-dust is found to be below 1350 °C and phase changes are observed above 1000 °C. Hence, the stone-dust mold is suitable for Al alloy casting. Therefore, a laboratory-scale casting trial is taken to cast A356 alloy using green stone-dust and silica sand mold. The hardness (HRB), as cast surface roughness (Ra) and microstructure of silica sand and stone-dust mold casting are evaluated and compared. It is observed that stone-dust mold shows higher hardness as compared to silica sand mold. Hence, stone dust mold may be used as an alternative to silica sand in Indian foundries for aluminum alloys casting. [ABSTRACT FROM AUTHOR]

An A356 alloy is a classic casting light alloy, which is able to be processed into complex geometrical shapes with tailored static and dynamic mechanical properties. As a promising material to reduce fuel and energy consumption in future vehicle designs, there is an interest in understanding the impact of heat treatments on the damping capacity of this alloy. The Granato–Lücke theory is used to detail the forced vibration response in gravity cast A356. It is shown that a solution treatment enhances damping capacity in lower stress states (i.e., strain-independent regime) due to the increase in weak pinning length. However, in high-stress states (i.e., strain-dependent regime), peak-aged (T6) samples display higher damping capacity. This is proposed to be originated by releasing dislocations from weak pinning points, which start bowing in the precipitates that act as strong pinning points. Based on these results, it is shown for the first time that the selection of heat treatments to optimize damping in forced vibration is highly dependent on the expected stress–strain state and must be considered in the design of cast components. [ABSTRACT FROM AUTHOR]

Anticipating the processes and parameters involved for accomplishing a sound metal casting requires an in-depth understanding of the underlying behaviors characterizing a liquid melt solidifying inside its mold. Heat balance represents a major factor in describing the thermal conditions in a casting process and one of its main influences is the heat transfer between the casting and its surroundings. Local heat transfer coefficients describe how well heat can be transferred from one body or material to another. This paper will discuss the estimation of these coefficients in a gravity die casting process with local air gap formation and heat shrinkage induced contact pressure. Both an experimental evaluation and a numerical modeling for a solidification simulation will be performed as two means of investigating the local heat transfer coefficients and their local differences for regions with air gap formation or contact pressure when casting A356 (AlSi7Mg0.3). [ABSTRACT FROM AUTHOR]

Purpose: This study aims to present a novel methodology for the evaluation of tribological properties of new nanocomposites with the A356 alloy matrix reinforced with aluminium oxide (Al2O3) nanoparticles. Design/methodology/approach: Metal matrix nanocomposites (MMnCs) with varying amounts and sizes of Al2O3 particles were produced using a compocasting process. The influence of four factors, with different levels, on the wear rate, was analysed with the help of the design of experiments (DoE). A regression model was developed by using the response surface methodology (RSM) to establish a relationship between the observed factors and the wear rate. An artificial neural network was also applied to predict the value of wear rate. Adequacy of models was compared with experimental values. The extreme values of wear rate were determined with a genetic algorithm and particle swarm optimization using the RSM model. Findings: The combination of optimization methods determined the values of the factors which provide the highest wear resistance, namely, reinforcement content of 0.44 wt.% Al2O3, sliding speed of 1 m/s, normal load of 100 N and particle size of 100 nm. Used methods proved as effective tools for modelling and predicting of the behaviour of aluminium matrix nanocomposites. Originality/value: The specific combinations of the optimization methods has not been applied up to now in the investigation of MMnCs. In addition, using of small content of ceramic nanoparticles as reinforcement has been poorly investigated. It can be stated that the presented approach for testing and prediction of the wear rate of nanocomposites is a very good base for their future research. [ABSTRACT FROM AUTHOR]

The spheroidization of the silicon eutectic phase in aluminum is an important parameter for casting and significantly influences the material properties. Sr has been used for a long time for eutectic modification in aluminum and many researches have been made on this subject. In this study, the effect of holding time after Sr addition on the mechanical properties and eutectic phase modification of the aluminum were investigated. 200 ppm Sr was chosen as the amount of Sr and the holding times were chosen as 20, 40 and 80 minutes. Tensile test was performed for the determination of mechanical properties and ultimate tensile strength and percentage of elongation values were measured. In order to quantify eutectic modification, the length / width (aspect ratio) ratios of eutectic silicon particles were measured. In addition, Bifilm Index of the molten metal was determined with the reduced pressure test (RPT). With the increase in the holding time, an increase in the aspect ratio and in the Bifilm Index was measured. It has been observed that the tensile strength and elongation values have decreased as the holding time has increased.

Aluminium alloys have found application in many areas like aerospace industries and automobiles specifically in Machine tool parts, aircraft wheels, pump parts, marine hardware, valve bodies and automotive pistons, owed to their strength to low weight ratio. The present study deals with the growing demand for more durable aluminum alloys for the engine components with improved mechanical property/ tribological properties majorly focusing on the area of wear and tear in engine piston systems. In the present research, the simultaneous effect of cobalt (Co) addition and wear testing factors on the wear resistance of Al-6.6Si-0.4Mg hypoeutectic alloy is investigated through response surface methodology (RSM), a system employed in the design of experiments. Using Minitab software, the regression analysis was done and an equation was formulated to forecast the wear rate and also to investigate the significance of each experimental parameter on the subsequent wear rate. It was found from the current research that, with a surge in the cobalt content, the wear resistance of the alloy increased. It was also noted that, the wear rate was found to increase with an increase in the sliding velocity and load. Whereas, wear rate decreases with an increase in the sliding distance. In order to obtain the minimal wear rate, optimal values for each parameter were found out. FESEM investigation was conducted on the worn-out specimen to evaluate the worn-out surface of the regular and modified alloy for different wear testing conditions.

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Production of the defect-free casting of aluminium alloys is the biggest challenge. Porosity is known to be the most important defect. Therefore, many cast parts are subjected to several non-destructive tests in order to check their acceptability. There are several standards, yet, the acceptance limit of porosity size and distribution may change according to the customer design and requirements. In this work, the aim was targeted to evaluate the effect of size, location, and distribution of pores on the tensile properties of cast A356 alloy. ANSYS software was used to perform stress analysis where the pore sizes were changed between 0.05 mm to 3 mm by 0.05 mm increments. Additionally, pore number was changed from 1 to 5 where they were placed at different locations in the test bar. Finally, bifilms were placed inside the pore at different sizes and orientations. The stress generated along the pores was recorded and compared with the fracture stress of the A356 alloy. It was found that as the bifilm size was getting smaller, their effect on tensile properties was lowered. On the other hand, as bifilms were larger, their orientation became the dominant factor in determining the fracture. [ABSTRACT FROM AUTHOR]

The experiments were planned to fabricate an A356 as a matrix material with 3, 6, 9, 12 wt. % of SiC and 3 wt. % of Gr as reinforcements to cast the hybrid composites at optimal process variable conditions using squeeze casting technique. Further T6 heat treated casted samples are prepared for testing as per standard procedure to record the responses like density, porosity, hardness, ultimate tensile strength, and percentage elongation respectively. There is a gradual increment in density because of adding an optimal level of up to 9 wt. % of SiC and 3 wt. % of Gr strengthening particles available in the A356 matrix and the porosity present in the sample diminishes, which in turn increases the hardness.

The A356 castings were fabricated using a well-developed temperature controlled permanent mold. To improve the strength and hardness of cast A356, the microstructures and mechanical properties of as-cast and T6 heat treated A356 alloy with various mold and pouring temperatures were studied. The results reveal that the undercooling is closely related to the mold and pouring temperatures. As the mold/pouring temperature changed from 258 °C / 680 °C and 270 °C / 680 °C to 288 °C / 650 °C, the in-situ undercooling is 12 °C, 17 °C and 11 °C, respectively. It is observed that the Si phase changes from long continuous flake to discontinuous globular-fibrous morphology after T6 heat treatment as the mold and pouring temperature is 270 °C / 680 °C, and the T6 heat treated specimens exhibit better mechanical properties in comparison to those as-cast ones with an increase of 162% and 102% in yield strength and elongation, which are 34.6% and 190% higher than the ASTM B108-03a standard, respectively. As a result, the tensile fracture morphology of the as-cast A356 alloy shows quasi-cleavage fracture and the T6 heat treated A356 alloy shows ductile fracture.

The present study addresses the utilization of induction furnace steel slag which is an anthropogenic waste, for enhancing the mechanical properties of a commercial aluminium alloy A356. Different weight percentage (3wt%, 6wt%, 9wt%, and 12wt%) of steel slag particles in 1 to 10 μm size range were used as reinforcing particles in aluminium alloy A356 matrix. The composites were prepared through stir casting technique. The results revealed an improvement in mechanical properties (i.e. microhardness and tensile strength) and wear resistance with an increase in weight percentage of the steel slag particles. This research work shows promising results for the utilization of the steel slag for enhancing the properties of aluminium alloy A356 at no additional cost while assisting at same time in alleviating land pollution.

The automobile industry has been concentrating on developing eco-friendly materials that improve the safety and fuel efficiency of automobiles. Aluminum alloys, well known as lightweight materials, have been studied, particularly as the demand for high-strength and lightweight materials has been increasing. This study focuses on the technique of rheocasting using electromagnetic stirring (EMS), which is a typical semi-solid method for manufacturing aluminum products. Focusing on EMS, the effect of current input methods on the castability, roundness, and mechanical properties of products manufactured by rheocasting was evaluated. A large electromagnet was used to stir the molten metal, with a maximum weight of 5 to 20 kg of molten metal used in industry, using two types of current input methods—direct current (DC) and alternating current (AC). The microstructure, roundness, and mechanical properties were evaluated by fabricating a tensile specimen using EMS experimentation. The experimental results showed that excellent castability appeared at solid fractions of 20 and 30%. In addition, when the products were manufactured with a solid fraction of 20% and an AC input, the apparent tensile strength was the highest at 177 MPa. The equivalent diameter of the α-Al particles was 53 μm and the roundness was 1.8.

Aluminum casting alloys are widely used in especially automotive, aerospace, and other industrial applications due to providing desired mechanical characteristics and their high specific strength properties. Along with the increase of application areas, the importance of recycling in aluminum alloys is also increasing. The amount of energy required for producing primary ingots is about ten times the amount of energy required for the production of recycled ingots. The large energy savings achieved by using the recycled ingots results in a significant reduction in the amount of greenhouse gas released to nature compared to primary ingot production. Production can be made by adding a certain amount of recycled ingot to the primary ingot so that the desired mechanical properties remain within the boundary conditions. In this study, by using the A356 alloy and chips with five different quantities (100% primary ingots, 30% recycled ingots + 70% primary ingots, 50% recycled ingots + 50% primary ingots, 70% recycled ingots + 30% primary ingots, 100% recycled ingots), the effect on mechanical properties has been examined and the maximum amount of chips that can be used in production has been determined. T6 heat treatment was applied to the samples obtained by the gravity casting method and the mechanical properties were compared depending on the amount of chips. Besides, microstructural examinations were carried out with optical microscopy techniques. As a result, it has been observed that while producing from primary ingots, adding 30% recycled ingot to the alloy composition improves the mechanical properties of the alloy such as yield strength and tensile strength to a certain extent. However, generally a downward pattern was observed with increasing recycled ingot amount. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to understand the effect of particle content, applied load and sliding speed on the tribological properties of A356-SiCP composites manufactured using a newly developed vacuum stir casting technique. Design/methodology/approach: A356 alloy reinforced with 10, 15 and 20 vol% SiC particles was prepared by vacuum stir casting. Tribological tests were carried out on block-on-ring tribometer under dry sliding conditions, room temperature. Wear mechanism was investigated by scanning electron microscope and energy dispersion spectrum. Findings: SiCP is homogeneously dispersed in the matrix. The increase in SiCP content decrease wear rate, but it leads to an increase in coefficient of friction. The wear rate increase and friction coefficient present different variation trends with increasing load. For A356-20%SiCP composite, when the load is less than 10 MPa, wear rate and friction coefficient under sliding speed of 400 rpm are lower than those of 200 rpm. Wear mechanism transition from abrasion, oxidation, delamination, adhesion to plastic flow as load and sliding speed increasing. Practical implications: Results of this study will help guide the use of A356-SiCP in many automotive products such as brake rotors, brake pads, brake drums and pistons. Originality/value: There are few paper studies the effect of particle content, applied load and sliding speed on the tribological properties of A356-SiCP composites. Aluminum matrix composites with uniform distribution of reinforcing particles were successfully prepared by using the newly developed vacuum stir casting technique. [ABSTRACT FROM AUTHOR]