Gravity Casting Research Articles

Effects of applied pressure and residual heat quenching on the mechanical and thermal properties of cast Al–Mg–Zn–Mn–Fe alloys

In this study, the effects of applied pressure (AP) and residual heat quenching (RQ) on the mechanical properties and thermal conductivities of Al-4.6Mg-3.6Zn-0.86Mn-0.48Fe alloys were investigated based on intensively microstructure analysis by scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM) and synchrotron X-ray tomography (SXT). The results indicated that AP and RQ did not change the type of intermetallic; instead, they reduced the length and quantity of lath-like Al6(Fe,Mn) and significantly refined the grain by increasing the cooling rate. Moreover, η′ precipitation particles were enriched near the grain boundaries, which was beneficial for the yield strength of the alloy; the AP + RQ sample exhibited the best mechanical properties of the ultimate tensile strength, yield strength and elongation of 269 MPa, 164 MPa and 11.4 %, respectively, which were 19 %, 17 %, and 83.8 % higher than those of the gravity cast (GC) sample. Moreover, the thermal conductivity of the AP + RQ sample did not show significant changes, which were attributed to the reduction in solid solute caused by the increased volume fraction of η′ precipitates, thus improving the thermal conductivity; however, the formation of numerous semi-coherent interfaces between η′ and the matrix led to increased lattice distortion, resulting in electron scattering.

Effect of Al on microstructure and mechanical properties of HPDC Mg-6Y-3Zn alloys

The effect of Al on microstructure and mechanical properties is investigated in novel Mg-6Y-3Zn (WZ63) alloys produced by high-pressure die-casting (HPDC). The morphology of (Al,Zn)2Y phase varies from lamellar to flower-like and then to block shape with 0.4–1.0 wt% Al. The HPDC alloys exhibit fine grain sizes ranging from 4 μm to 7.4 μm, and significant grain refinement is obtained with Al as low as 0.4 wt%, which is different from that in gravity casting. The (Al,Zn)2Y phase is the crack source, and the dimple depth and elongation (EL) reduce with increasing Al content. Still, all the studied HPDC WZ63-xAl alloys maintain excellent tensile properties, keeping 256–274 MPa for tensile strength (UTS) and 7.4–9.7 % EL at room temperature and 188–213 MPa UTS and 10–35 % EL at 250 °C. Optimal mechanical properties are obtained with Al content around 0.4–0.5 wt%.

3D numerical simulation and experimental validation of resin-bonded sand gravity casting: Filling, cooling, and solidification with SPH and ProCAST approaches

This article provides a comprehensive investigation into the resin-bonded sand gravity casting process, with a focus on the filling, cooling, and solidification steps. The research combines numerical simulations and experimental validation in a three-dimensional (3D) configuration, utilizing a realistic filling system. The study employs three approaches—experimental tests, Smoothed Particle Hydrodynamics (SPH) simulations, and ProCAST simulations—to analyze the filling, cooling, and solidification steps. Two different molds were used in the experiments. The first mold has a transparent glass component in front of the plate, enabling observation and recording of the filling process, while the second mold, used solely for thermal analysis, did not incorporate any glass component. The SPH approach yields more accurate results for the filling time, liquid level height, and morphology when compared to ProCAST. The discrepancy in final filling time for the desired casting part between the experiment and SPH is 5.13 %, and the difference between the experiment and ProCAST is 15.38 %. Additionally, the cooling and solidification steps are investigated through an analysis of cooling curves. The numerical methods demonstrate slightly higher cooling rates and deviations in solidification times compared to the experimental data, mainly due to the thermal Neumann boundary condition. Furthermore, the average discrepancy in solidification time for five points of the intended casting component between the experiment and SPH is 8.60 %, whereas when compared with ProCAST, the discrepancy increases to 9.13 %.

Evaluation of Interfacial Thermal Resistance of Al-Si Alloy by Using Image-Based Simulation

Interfacial thermal resistances of Al-Si alloys were evaluated by comparing the measured thermal conductivities and the simulated thermal conductivities. Al-7%Si, Al-18%Si and Al-18%Si held in the solid-liquid coexistence temperature for 90 minutes were fabricated by gravity casting. Thermal conductivities were measured with the steady state thermal conductivity measuring device. Thermal conductivities were also simulated by using optical microscope images. Comparing the measured thermal conductivities and the simulated thermal conductivities, interfacial thermal resistances in Al-Si interfaces were evaluated as about 2.5-4.8×10-9 m2K/W.

Dry and Lubrication Sliding Wear Characteristics and Wear Mechanism Mapping for In Situ Al–25Mg2Si Composites

This study investigates the wear characteristics of Al–25Mg2Si composite synthesized via gravity casting. The research aims to understand the influence of applied load, test temperature, contact condition (dry and lubrication), and sliding distance on wear characteristics. Results show that higher loads and temperatures lead to increased wear loss and coefficient of friction. The worn surface morphology for higher loads and temperature shows deeper scratches and grooves, indicating severity in wear. The debris size and volume increase with an increase in load and temperature. The dominant mechanism is abrasive, adhesive, and oxidative for both the room‐ and high‐temperature dry sliding conditions. However adhesive and oxidative wear increase with the increase in test temperature. Abrasive wear is the only wear mechanism present during the lubricating sliding condition. Wear transition is noticed during the wear map analysis subjected to load, temperature, and sliding distance. In the case of room‐temperature test, severe–moderate–mild wear transition occurs with the increase in sliding distance and mild–moderate–severe wear transition occurs with the increase in test temperature and applied load. The roughness of the worn surface increases with an increase in applied load and temperature and the use of lubricant hugely reduces the surface roughness.

Mechanical Properties Enhancement of AZ91 Magnesium Alloy Reinforced with Various Ratios of Titanium Particles and Processed by ECAP

This study utilized AZ91 magnesium-aluminum alloy as the matrix for magnesium-based composites, reinforced with micron-sized titanium (Ti). Gravity casting and mechanical stirring were employed to fabricate specimens with 0 wt.%, 0.3 wt.%, and 0.5 wt.% Ti reinforcement. Heat-treated samples underwent Equal Channel Angular Pressing (ECAP), and microstructures were analyzed via SEM and XRD. The experimental results demonstrate that the addition of micron-sized titanium improves the yield strength, ultimate tensile strength, and hardness. The inclusion of 0.5 wt.% titanium powder resulted in a 17.5% increase in ultimate tensile strength and a 37% increase in yield strength. After secondary processing with ECAP, the ultimate tensile strength showed an additional 25% increase, while the yield strength increased by 13.5%. Vickers hardness test results reveal a significant 13.7% strength improvement with the addition of 0.5 wt.% titanium powder, and after ECAP secondary processing, there was a marginal additional increase of 0.8%.

Study on casting simulation and wear properties of honeycomb configuration ZTAp-Fe composite

The primary objective of this research is to develop a honeycomb configuration ZTAp-Fe composite, with varying concentrations of ZTAp (zirconia-toughened alumina particles) at 5 wt%, 10 wt%, and 15 wt%, to address wear-related issues in mining machinery components. A numerical simulation of the casting process to study the temperature field variation in composites and gravity casting was subsequently performed using 30SiMn steel liquid. A comprehensive examination of the composite's characteristics was conducted, employing XRD, SEM, EDS, three-body abrasive wear, and scratch testing. The study revealed a metallurgical bonding between the interface of 30SiMn steel and the iron matrix, characterized by a fusion zone with a width of approximately 182 μm. Furthermore, the honeycomb configuration of the preform was found to enhance heat transfer during the casting process. Both 30SiMn steel and the iron matrix exhibited a room temperature organization of α-Fe, and the micron granular precipitates in the iron matrix are (Fe, Cr)7C3. However, it was observed that when the ZTAp content reached 15 wt%, particle accumulation hindered heat transfer, which led to pore defects, resulting in poor mechanical bonding between ZTAp and the iron matrix. Compared to various three-body abrasive wear loads (50 N, 90 N, and 130 N), the wear properties initially improved with an increase in ZTAp content from 5 wt% to 15 wt% but then weakened. The presence of hard-phase ZTAp was found to play a significant role in blocking scratches, and composites with 10 wt% ZTAp content exhibited excellent wear properties.

Chemical Composition Effects on the Microstructure and Hot Hardness of NiCrSiFeB Self-Fluxing Alloys Manufactured via Gravity Casting

Ni-Cr-Si-Fe-B self-fluxing alloys are commonly used in hardfacing applications; in addition, they are subjected to conditions of wear, corrosion, and high temperatures, but are not used in casting applications. In this work, gravity casting is presented as a potential manufacturing route for these alloys. Three alloys with different chemical compositions were investigated with a focus on microstructure characterization, solidification path, and strengthening mechanisms. Phases and precipitates were characterized using a field emission scanning electron microscope employing energy-dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and electron backscatter diffraction. Nano- and microhardness indentations were performed at different phases to understand their contribution to the overall hardness of the studied alloys. Hardness measurements were performed at room temperature and high temperature (650 °C). The borides and carbides were the hardest phases in the microstructure, thus contributing significantly to the overall hardness of the alloys. Additional hardening was provided by the presence of hard Ni3B eutectics; however, there was also a small contribution from the solid solution hardening of the γ-Ni dendrites in the high-alloy-grade sample. The amount and size of the different phases and precipitates depended mainly on the contents of the Cr, C, and B of the alloy.

Recycling of Hard Disk Drive Platters via Plastic Consolidation.

The paper presents the comparison of two methods of recycling aluminum from HDD platters-the melting method and the method of plastic consolidation. The main elements of HDD memory, i.e., data carriers (platters), were examined via the percentage share of the total HDD mass and also via EDS analysis. The most common are platters made of the aluminum alloy series 5XXX, which are covered with a thin magnetic layer made of nickel. The research involved removing data carriers from about 30 HDDs and fragmenting them. The next step was to divide the platters into three groups; one was melted, the second was subjected to plastic consolidation, and the third group was fragmented into chips and also subjected to the consolidation process. Then, in the process of co-extrusion, rods were extruded from each material, and were subjected to EDS analysis, microstructure testing, Vickers hardness, and uniaxial tensile tests, and then the obtained results were compared. The obtained results of the microstructural tests in the case of gravity cast material confirmed the presence of the Al3Ni globular phase in the matrix. In the case of pressed and extruded materials, the Al3Ni phase appeared at the Ni-AlMg contact. After plastic consolidation, all the tested rods were characterized by their comparable strength properties (a tensile strength of 250 MPa and yield strength of 105 MPa).

Effect of Bi Content on the Microstructure, Mechanical and Tribological Properties of Cu-Sn Alloy.

To reduce the use of the toxic Pb element in the Cu-Sn alloy with high friction performance, Cu-xBi-10Sn alloys with different Bi contents were prepared by gravity casting, and the effect of Bi content on the microstructure, mechanical properties and wear property of Cu-Sn alloys were studied. The results showed that the Bi element was distributed in bands or long strips on the dendritic arms and did not form compounds with other elements. With the increase in Bi content, the hardness and tensile strength of Cu-xBi-10Sn alloys present a trend of increasing first and then decreasing. When the Bi content was 7 wt.%, the maximum hardness value was obtained, and the ultimate tensile strength was close to that of Cu-10Pb-10Sn alloy. Compared with Cu-10Pb-10Sn alloy, Cu-7Bi-10Sn alloy also possessed better friction reduction and wear resistance under the oil lubrication condition.

Analysis of the Quality of Incoming AlSi9Mn Alloy Ingots

Previous research revealed that the quality of the ingots produced by different primary or secondary alloy suppliers can differ remarkably. In this way, the quality of the liquid metal and the castings produced from it can be affected by the impurity content of the ingots used as charge material. In this work, a modified reduced pressure test (RPT) technique, which is based on the remelting of samples extracted from ingots, was applied to investigate the quality of primary AlSi9Mn ingots made by horizontal direct-chill (HDC) casting and gravity casting techniques. For the evaluation of metal quality, image analysis of the cross sections was applied. Pore area fraction, number density, normalized bifilm index, and normalized total pore perimeter were determined, and the relationships between the different metrics were analyzed. The results were compared with the melt quality assessment of the as-melted batches made from the ingots. Solidification simulations, thermal analysis, and microstructural investigations were conducted to investigate the solidification conditions of traditional and remelted RPT samples. Based on the results, the HDC cast ingots possess lower oxide and gas concentrations, which can be traced back to the differences in the melt preparation and casting technologies of the ingots. The comparison of the parameters evaluated by image analysis revealed that there is a strong linear relationship between normalized bifilm index and normalized total pore perimeter. The possible sources of error in ingot quality evaluation are highlighted.

Optimization and fuzzy model for evaluation of mechanical and tribological properties of Al-CNT-Si3N4 based nano and hybrid composites

Silicon Nitride (Si3N4) has an extraordinary combination of high hardness, strength, toughness, and advanced properties like excellent wear and corrosion resistant, thermal shock resistance. Also, Carbon Nano Tube (CNT) has grasped interest among the researchers owing to its superior mechanical and thermal properties. Hence, the present study intents to fabricate Al matrix reinforced with Si3N4 nano particulate and Al matrix reinforced with CNT and Si3N4 particulate called hybrid composite via gravity casting route. The fabricated composites were tested for compression test, hardness and tribological test. The L9 orthogonal array was selected to conduct the tribological test in dry sliding conditions. Furthermore, SEM, an optical microscope, and image analysis tools were used to characterize the created composites. To determine the ideal operating conditions of the tribology test, analysis of variance was performed. The correlation between the input parameters and the wear rate, COF, was established using regression models. In order to predict the rate of wear with greater than 95% accuracy, a fuzzy model was developed based on the experimental data.

New Addressable Applications for Rheocasting to Escape from an Oversupplied Market

The current market change of aluminium HPDC castings started with the “Dieselgate”. First, there was a shift from diesel to petrol engines. In the second step, hybrid and battery-powered cars gained significant market shares in sales statistics. Therefore, lucrative powertrain components are falling away. As powertrain foundries still want to utilize their machines to capacity, they are pushing into the structural castings market. As a result, there is an oversupply of casting machines here, which massively depresses prices and, thus, margins for tenders. With rising energy costs, these declining margins were eaten up, bringing foundries into crisis. Implementing Rheocasting at the existing die-casting cells is the solution to move into new market shares that are now not accessible in conventional HPDC.One of the new applications is electronic housings, high wall thickness parts, and fatigue bearing parts. These parts are commonly manufactured in sand or gravity castings because of their high wall thickness and low tolerance of porosity. Rheocasting is the perfect process for high-wall thickness components. Because of the semisolid melt preparation and the lamellar filling behavior, these components can be manufactured from the same alloy without pores or voids.This flow behavior of the semisolid slurry also results in a longer flow length. Slower casting speeds and lower pressure settings result in lower clamping forces. This gives an advantage in production costs and targets battery constructions made of castings and sheet metal. Structural battery housings must be leak-tight, even in a crash event. Having it in one casting instead of an assembly reduces the leakage area and improves crash performance.Another industry that relies on Rheocasting is the telecommunications industry. The power electronics in these 5G modules are significantly larger and generate much more waste heat. Until now, many antennas have been actively cooled or milled from a block of aluminum. The milled housings are significantly too expensive to enable series production. Therefore, the goal is to reproduce the passively cooled modules in die casting. Due to the process, the thermal conductivity in conventional HPDC is around 120 to 130 W/m*K. Similarly, no slim cooling fins can be formed. Only the Rheocasting process makes it possible to cast other alloys with low proportions of alloying elements, such as AlSi2Mn. This allows fins with a wall thickness of down to 0.4 mm and thermal conductivity of up to 190 W/m*K.Rheocasting enables access to market segments out of reach. These bring an unbeatable cost advantage against the current suppliers: gravity and sand casters. The low cycle time in Rheocasting brings back the high margins needed to sustain the business. Also, these products can be delivered with even better properties on smaller casting machines.

Thermochemical modelling and mechanical property of the Al-7.6Si-xZr alloy

This study utilised the gravity casting method to modify hypoeutectic Al-7.6Si alloys with Zr at varying weight percentages (0.1%, 0.2%, and 0.3%). The unmodified alloy typically consists of a needle or platelike eutectic silicon within the dendritic α-Al phase. The addition of Zr increases the liquidus temperature of the alloy and results in the formation of ZrSi and ZrSi2 compounds, which act as nucleation sites for both the eutectic Si and α-Al grains. As a result, the needle or platelike eutectic silicon transforms into a fibrous structure with a more uniform distribution, and the α-Al phase becomes finer and globular. These microstructural changes lead to improved bulk hardness, ductility, and mechanical properties of the alloy.

Quantifying the effects of hydrogen concentration and cooling rates on porosity formation in Al–Li alloys

The addition of Li to Al alloys produces such benefits as a 6% increase of modulus and a 3% weight reduction upon adding 1 wt% Li, and yet it has led to difficulties for manufacturing due to the highly active Li and 25 times equilibrium [H] concentration in the liquid at elevated temperatures. In this study, the 3D porosity morphology was quantified using the X-ray computed tomography (X-CT) from both sand gravity and vacuum castings. A cellular automaton model has been adopted to predict porosity distribution as a function of equilibrium hydrogen concentration and thermal boundary conditions. Combining experimental and simulation results, it was found that the mechanical properties of vacuum casting Al–Li alloy have been improved significantly due to the reduction of hydrogen porosity. The prediction of porosity as a function of hydrogen levels and cooling conditions agrees well with experiments, and porosity has been found to decrease Young's modulus and initiating cracks in Al–Li alloys.

Development of manufacturing technology for a hybrid induction rotor

General Motors is developing designs and manufacturing processes for new generations of electric motors intended for use in electric vehicles. There is interest in replacing the aluminum traditionally used in induction motor rotors with copper to improve motor capability. This work explored the use of casting aluminum end-rings to copper conducting bars (spokes) in the fabrication of copper rotors. Gravity casting trials were carried out in experimental foundry. Pure aluminum end-rings were overcast and interlocked over C101 copper conductor bars encapsulating a laminate stack of highly magnetic steel. Steel permanent mold was designed and constructed specifically for the project. The mold was capable of casting one end-ring of the rotor at a time and allowed for the assembly to be reoriented for casting of the opposite end-ring. The objective of this work is to investigate the effects of intermetallic compound (IMC) formation at the interfaces of cast-bonded Cu-Al bars on the rotor mechanical integrity and electrical resistance. The Cu-Al bonding strength was measured by tension tests, and the influence of IMC layer variation on the tension load and electrical resistance were analysed. This research phase showed that sufficient bonding and interlocking were achieved among the aluminum and copper by using a special feature and/or flux at the bar ends in the permanent mold casting process. The paper reviews the data collected for evaluation of the quality of hybrid rotor cage.

Vacuum Stir Cast Developed Aluminium Alloy Hybrid Nanocomposite Performance Compared with Gravity Cast: Mechanical and Tribological Characteristics Study

Vacuum Stir Cast Developed Aluminium Alloy Hybrid Nanocomposite Performance Compared with Gravity Cast: Mechanical and Tribological Characteristics Study

A 2D filling and solidification benchmark test: validating smoothed particle hydrodynamics (SPH) simulations for sand gravity casting

A 2D filling and solidification benchmark test: validating smoothed particle hydrodynamics (SPH) simulations for sand gravity casting

Microstructure and mechanical properties of suction-cast aluminium–cerium alloys

ABSTRACT In the present investigation, the microstructure and tensile properties of Al–12Ce, Al–12Ce–4Si, and Al–12Ce–4Si–0.4Mg alloys (wt-%), fabricated by suction-casting (SC) and gravity-casting (GC) were compared. The SC alloys exhibited finer grains and a higher number of precipitates than the GC alloys. Addition of Si and Mg in Al–12Ce alloy improved the hardness substantially. Incorporation of 4Si and 0.4Mg enhanced the yield and tensile stress but reduced ductility in the SC alloys. The SC Al-12Ce-4Si-0.4Mg alloy illustrated the best hardness and tensile strength. The fracture behaviour of the SC Al–12Ce alloy changed from quasi-cleavage to complete cleavage fracture following the addition of 4Si and 0.4Mg.

Influence of squeeze casting pressure on nanoparticle distribution and mechanical properties of nano-SiCp/Al−Cu composites assisted with ultrasonic vibration

The influence of squeeze casting pressure on nanoparticle distribution and mechanical properties of 2 wt.% nano-SiCp/Al−Cu composites assisted with ultrasonic vibration was investigated. Results show that as the applied pressure increases from 0 to 400 MPa, the α(Al) grains are significantly refined at first and then the refinement trend slows down, and the porosity of composites is gradually reduced. When the applied pressure is 400 MPa, α(Al) grain size is reduced from 105 to 25 μm, and the nanoparticle distribution is significantly improved, resulting in the optimal mechanical properties of the composites. The ultimate tensile strength, yield strength and elongation of the composites are 290 MPa, 182 MPa and 10%, which are 52.6%, 25.5% and 400% higher than those of the nano-SiCp/Al−Cu composites prepared by gravity casting (0 MPa). The enhancement in strength and elongation of nano-SiCp/Al−Cu composites under high pressure is mainly attributed to grain refinement, reduction of porosity and uniform distribution of nanoparticles.