International Journal of Metalcasting最新文献

In a foundry, optimizing the charge mix is critical to achieving consistent quality, cost-efficiency, and desired qualities in the final metal or alloy product. This paper describes a data analytics-driven strategy for optimizing the charge mix by lowering the cost of the scrap used to prepare the molten metal while maintaining the required chemical composition, tensile strength, and hardness required by the foundry for manufacturing gray cast iron products (Grade FG 220). The linear programming approach is used for this purpose where all the constraints are strictly met. Three categories of constraints are used for this purpose, i.e., composition constraint, foundry constraint, and material grade constraint. In the linear programming approach, the feasible region is considered as an ellipsoidal region and the developed convex optimization problem is iteratively solved. The result showed potential cost savings could be obtained, accompanied by the needed alloy chemical composition and quality.

This research analyzes the technical feasibility of manufacturing jewelry castings using the lost wax technique, substituting wax by the use of resins within the framework of 3D stereolithography printers. To achieve this goal, a pair of distinct 3D ring designs have been crafted: a robust signet ring and an intricate filigree ring. The purpose behind this decision is to determine whether the unique features of these two different designs have any noticeable effect on the result. Five different commercial resins have been utilized, with one of them explicitly formulated for casting purposes. Non-castable resins generate a unique, weathered appearance, due to the variability in ash residue within the mold after resin combustion, yielding unpredictable outcomes and diverse sample characteristics such as grainy texture, cracks, and a corroded effect. Examining the castable resin reveals its optimal performance for smaller elements like the filigree ring, showcasing remnants of supports or layers originating from the resin's printer curing process. On the contrary, larger resin-abundant objects like the signet ring result in notable flaws, attributed to gas accumulation within the mold, exerting internal pressure and causing mold rupture, leading to metal leakage.

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The proposed research of magnesium alloy (AZ61) hybrid nanocomposites followed by advanced liquid-state processing associated with the squeeze die-cast process overcomes the drawbacks (micro-voids, agglomerated particles, and oxidation during open melting) of conventional liquid stir gravity die casting. The boron nitride (BN) and silicon carbide (SiC) nanoparticles are the source of hybrid filler material for composing the AZ61 alloy hybrid nanocomposites. Finding the role of hybrid filler materials during the squeeze casting processing on surface morphological, mechanical, and tribological performance is evaluated by the ASTM standard, and its outcomes are compared with cast AZ61 alloy and AZ61/3 wt% of BN nanocomposites. The advanced liquid-state processing features with squeeze die cast proved void-free structure composite surface and homogenous particle distribution was confirmed by scanning electron microscope analysis. The crystal peaks are confirmed with the support of X-ray diffraction analysis. Besides, the actions of hybrid filler material in AZ61 alloy matrix provided significant results and the composite contained with 3 wt% of BN 7.5 wt% SiC offered improved density (1.851 g/cc), reduced porosity (0.54%), optimum yield, and ultimate tensile strength performance of 184.7 ± 9 and 307.1 ± 6 MPa, maximum hardness (84.6 ± 4 HV), hiked impact strength (24.2 ± 1 J/mm²), reduced volumetric wear loss (0.97 mm³/m) and improved coefficient of friction (0.47). The best functional performance of composite sample (AZ61/3 wt% BN/7.5 wt% SiC) is advised for automotive top roof frame applications.

Knowledge of the relevant stable equilibrium phase diagram is a prerequisite for taking account of deviations from equilibrium when modeling the solidification of silicon cast irons. While a linear description is practical for silicon contents up to 3 wt%, the curvature of the austenite liquidus at higher silicon contents necessitates the use of second-order polynomials. This study was carried out with the aim of obtaining an accurate description up to 4.5 wt% silicon, representative of today’s emerging high-silicon cast irons. In addition, alloying with up to 1 wt% copper, 0.5 wt% manganese and 0.25 wt% chromium and phosphorus was considered. In parallel to a description of the liquidus of austenite and graphite, the austenite-liquid partition coefficients of all alloying elements have been described. This paves the way for future work aimed at providing an accurate description of microsegregation and other non-equilibrium phenomena occurring during the solidification of silicon cast irons.

Permeability of shell molds for investment castings used in high-valu segments including aerospace, biomedical and defense plays a very important role in achieving better quality castings especially free from filling-related defects. Though, guidelines related to permeability measurement techniques have been established for twenty years, the permeability measurement device is not available in most investment casting foundries. This can lead to issues when establishing foundries to supply investment castings for high-value segments. A specific permeability measurement device has been developed by following guidelines published by a globally accepted standard body that further has been facilitated with the fundamentals of the Internet of Things. Different mold materials (using zirconium sand, aluminum silicate and fused silica) that are used in shell mold making for high-valued segments have been tested for establishing benchmark values of permeability. These values of permeability were observed in the range of 8 × 10^-11–37 × 10^-11 cm² to achieve better quality shells as well as investment castings.

In this study, the effects of 10 wt% Zn addition on the microstructure and properties of Al12Si EN AC 44100 alloy were investigated. For this purpose, EN AC 44100 and EN AC 44100 + 10 wt%Zn alloys were fabricated by permanent mold casting. The microstructural examinations were performed using standard metallographic techniques. The phases in microstructures were identified by energy dispersive spectroscopy and X-ray diffraction analyses. The yield strength, ultimate tensile strength, and elongation to fracture of the alloys were determined by tensile testing after measuring their Brinell hardness. The tribological properties of the alloys were examined using a ball-on-disk type wear test apparatus. It was observed that the microstructure of the EN AC 44100 alloy consists of aluminum-rich α, primary silicon and β (Al–Fe–Si) phases together with the eutectic Si particles. The addition of zinc resulted in a significant increase in the hardness and the strength of EN AC 44100 alloy but a considerable decrease in its friction coefficient and wear volume by modifying the microstructure of it. The modification caused a reduction in the size of α grains and eutectic silicon particles. Effects of zinc addition on the mechanical and wear properties of the EN AC 44100 alloy were discussed in terms of the observed microstructural changes.

The present study was undertaken to elaborate on the parameters controlling the microstructural characterization of A319.2 Al–Si alloys, as a function of iron content (0.12–0.8%), Sr addition (~250 ppm), and solidification time (586s vs 513s). For comparison, selected conditions were applied to A356.2 alloys. The use of a hot graphite mold and an end-chill mold provided different solidification rates along the liquid/solid interface, corresponding to DAS values in the range of ~23–85μm, corresponding to levels of 5, 10, 30, 50, and 100 mm above the chill end. Addition of strontium leads to fragmentation of β–Al₅FeSi platelets. Under similar Fe level and solidification rate conditions, the A319.2 alloys exhibit larger pore sizes than the A356.2 alloys, due to the absence of the (Al–Al₂Cu) reaction in the latter and hence longer solidification time. Four types of iron intermetallics were reported viz., δ-, α-, β-, and π-phases.

This study investigates the influence of magnetic fields on the microstructure and mechanical properties for the investment casting A356 Al–Si alloy. A356, known for its significant application in aerospace, defense, and automotive industries, was subjected to various intensities of magnetic fields generated by Helmholtz coils during the investment casting process. Additionally, the alloy was modified with the addition of Al–5Ti–B master alloy, and samples were subjected to T6 heat treatment. The aim was to explore the combined effects of magnetic field, grain refiner, and heat treatment on the alloy’s microstructural evolution and mechanical properties. The characterizations of A356 alloy included tensile strength, Vickers hardness, metallography, scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. The results indicated that magnetic fields applied during the casting process significantly influence the grain refinement of α-Al and the spheroidization of the eutectic silicon, leading to improve its mechanical properties. The study also examined the effects of magnetic fields on the distribution and morphology of eutectic silicon and Mg₂Si phases after T6 heat treatment. The findings of this research provide valuable insights in optimizing investment casting processes and enhancing the material properties of A356 alloy, which will offer potential applications in improving the quality and performance of cast components in various industrial sectors.

Due to severe acoustic attenuation, the effectiveness of single-source ultrasonic vibration (SUV) in dispersing reinforcement particles within Al matrix composites is limited, particularly when dealing with high weight fractions. In this study, a short-spacing multi-source ultrasonic vibration (MUV) technique, specifically quad-source ultrasonic vibration (QUV), was introduced to prepare SiC_p/A356 composites with a high weight fraction of 15wt.% SiC particles. The characteristic of acoustic streaming and the dispersion of particles were systematically investigated through numerical simulations and physical experiments. The results reveal that QUV mitigates acoustic attenuation and expands the potential cavitation region (exceeding the cavitation threshold of 1.1 MPa) compared to single-source ultrasonic vibration (SUV). The synergistic effect of multiple ultrasonic waves not only elevates cavitation intensity but also enriches the structures of acoustic streaming, significantly reducing agglomeration and improving the dispersion of SiC particles within the Al matrix. Without ultrasonic treatment, only a small proportion of SiC particles are embedded in the Al matrix, with an S_SiC/S_t ratio of merely 2.23%. However, as the number of ultrasonic sources increases, the agglomeration of SiC particles was relieved, and the resultant holes diminish. Remarkably, under QUV treatment, the holes in the composites virtually disappear, and the S_SiC/S_t ratio increases to 9.82%. Additionally, the composites exhibit superior mechanical properties, with a tensile strength of 200 MPa and an elongation of 7.0%, which are 10.5% and 38.5% higher than those achieved using SUV, respectively.