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International Journal of Metalcasting
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1939-5981 - ISSN (Online) 2163-3193
Published by Springer-Verlag Homepage  [2351 journals]
  • Metalcasting Industry Research
    • PubDate: 2019-03-19
       
  • Effect of Vibration on Interdendritic Feeding of
           AL–5%CU–0.4%MN Alloy
    • Abstract: In this study, the effect of vibration on the interdendritic feeding of Al–5%Cu–0.4%Mn alloy was investigated using vibration casting experiments and physical simulation. The solidification characteristics of the zinc-oxide paste (used as a mold coating to prevent sand burn during casting) resulted in shrinkage and porosity defects. The experiments were designed to show that vibration can improve feeding and reduce defects. The aqueous solution of sodium carboxmethyl cellulose (CMC) with the same rheological characteristic of metal melt was used in the physical simulation. The seepage calculation model of semisolid fluid in porous media under vibration was established, and the finite difference method and dynamic mesh technique were used to solve the model numerically. The casting results show that vibration can improve the feeding capacity and reduce shrinkage defects of Al–5%Cu–0.4%Mn alloy in gravity sand casting. The physical simulation results show that mechanical vibration can change the blocked structure at the seepage entrance, improve the permeability of porous media and reduce the resistance of interdendritic feeding. Mechanical vibration with the smaller frequency combined with the larger exciting force, or the larger vibration frequency combined with the smaller exciting force, can promote the seepage flow. Meanwhile, the numerical simulation of one-dimensional semisolid fluid seepage reveals that vibration can form a wave field in the porous medium, which can reduce the adhesion force between fluid and the capillary wall and destroy the boundary layer of fluid, thus promoting the seepage velocity.
      PubDate: 2019-03-18
       
  • Open-Source MATLAB Code for Hotspot Identification and Feeder Generation
    • Abstract: An open-source code for identifying metal casting hotspots and generating feeder geometries is outlined. The code takes two inputs and produces feeder information and an interactive visualization. The analysis requires no human interaction. The effects of the code applied to three example geometries are shown. Explanations of code choices, alternatives, assumptions, limitations, and extensions are discussed. A method for using the code to automate casting optimization workflows is also discussed. The code is made available verbatim, both in text and at a publically available repository online.
      PubDate: 2019-03-15
       
  • Permafrost Analysis Methodology (PAM) for Ceramic Shell Deformation in the
           Firing Process
    • Abstract: The deformation of ceramic shell poses a potential and uncertain threat on the dimensional accuracy of the final casting in the investment casting process. In this paper, a finite element analysis method (FEM), permafrost analysis methodology (PAM), is used to simulate the deformation of the ceramic shell in the firing process. In the PAM, the porosity and the phase transformation of the ceramic shell in the firing process are taken into consideration. The comparison of simulation and experimental results indicated that the PAM can predict the deformation of the ceramic shell with high accuracy. The work of this paper presents a new approach to simulate the deformation of the ceramic shell, and there is a great significance to improve the dimensional accuracy of the final casting in the investment casting process.
      PubDate: 2019-03-06
       
  • Cupola Furnace Slag: Its Origin, Properties and Utilization
    • Abstract: A cupola furnace is the most frequently used furnace aggregate for cast iron production. A by-product of the production of cast iron in cupola furnaces is cupola slag. Its amount is 40–80 kg per 1 tonne of the produced cast iron, and that is one of the reasons why this material is not as favoured as, for example, the blast-furnace slag. The purpose of this article is to provide the basic information on the formation of slag in a cupola furnace, and its chemical composition, structure and current potential applications. The greatest potential for the use of cupola slag is in the building industry; therefore, a section of the present article deals with the property that plays an important role particularly with regard to the use of slags in the building industry, i.e. the slag hydraulicity. The achieved results indicate that the hydraulicity of the cupola slag is incomparable with the hydraulicity of the blast-furnace slag; this may be associated with the problems that arise when the slag of this type is used in the building industry. The authors used the air-cooled as well as granulated slags from cupola furnaces in the production of concrete that was made from the slags alone. While the air-cooled slag may be used as a partial replacement for the blast-furnace slag in concrete mixtures, the use of granulated slag from cupola furnaces as a replacement for granulated blast-furnace slag in cement-free concrete has not proven to perform well.
      PubDate: 2019-03-01
       
  • Microstructural Characteristics, Mechanical Properties, Fracture Analysis
           and Corrosion Behavior of Hypereutectic Al–13.5Si Alloy
    • Abstract: Hypereutectic Al–13.5Si alloy containing 1.47% of copper and 1.30% of magnesium was designed as a potential material for internal combustion engine pistons. The optical microscopy and scanning electron microscopy (SEM) revealed the fine dendrites of α-Al phase and significantly dispersed eutectics in as-cast specimens. Several intermetallic phases were observed indicating different crystallization velocities and alloy composition nonuniformities. The tensile testing and hardness measurements performed at room temperature have shown an excellent tensile strength and hardness of as-cast specimens, but low elongation due to a complex multiphase structure. The mechanical examinations at 250 °C and 300 °C have presented a decrease in tensile strength and an increase in elongation, while hardness was slightly changed. The fractographic analysis has shown the features of the brittle as well as ductile fracture. The areas of dimples and areas containing particles with smooth surfaces were detected. Electrochemical methods, Tafel linear polarization, cyclic voltammetry, chronoamperometric measurement and impedance spectroscopy were employed to determine the corrosion behavior of as-cast specimens in 0.5 M NaCl solution. The resistant oxide layer formed on the surface was not entirely consistent due to the appearance of intermetallic phases. SEM examinations of corroded samples did not discover severe pits on their surfaces.
      PubDate: 2019-02-28
       
  • Development and Application of Cast Steel Numerical Simulation System for
           Heat Treatment
    • Abstract: A numerical simulation system for heat treatment of cast steel was developed using C++ environment, which has been integrated into the InteCAST platform as a new feature module. The system mainly includes heat treatment process inquiry module, initialization and property parameter setting module, automatic import and display module of time-temperature-transformation (TTT) and continuous cooling transformation (CCT) curves, heat treatment process design module, organization, performance and stress–strain prediction module. This paper introduces the mathematical model and numerical solution algorithm in the process of numerical simulation of the heat treatment organization, performance and stress–strain as well as the interface operation process and application examples of the system.
      PubDate: 2019-02-14
       
  • Effect of Strontium Modification on Porosity Formation in A356 Alloy
    • Abstract: Sr-modified Al–Si alloys are promising for automotive and aerospace industrial applications. However, Sr modifier increases the porosity level and deteriorates the performance of the castings, which has confused foundrymen for several decades. Many researchers have studied the phenomenon, but there is no unified explanation. In this study, two types of Sr modifier (50 ppm and 250 ppm) are applied to explore the effect of Sr modification on the surface oxide film and the porosity of the castings. The results of optical emission spectrometer and X-ray photoelectron spectroscopy (XPS) reveal that the surface oxide film has some degree of Sr segregation. Combining the high-resolution XPS spectrums with electron probe microanalysis–wavelength-dispersive spectroscopic (EPMA–WDS), it can be found that a small amount of SrO is distributed on the Al2O3 film. Further analyzing the surface oxide film by scanning electron microscopy and EPMA mapping, it can be concluded that the compact Al2O3 film is fractured by congregated SrO and then some new Al2O3 films and oxide inclusions are formed in the cracks. Those can cause the increase in the porosity. And the result of reduced pressure test (RPT) shows that the densities of RPT samples are decreasing with the increase in Sr content. It means that Sr modification dose increase the porosity of the A356 alloy castings.
      PubDate: 2019-02-13
       
  • Electromigration Effects During Resistance Brazing of Zn–Al/Al
           System
    • Abstract: Liquid filler metals often experience electromigration (EM) effects during resistance brazing due to the high current density, which can affect the microstructure of the joint and reduce its strength. However, to date, few studies have investigated this effect. Here, a Zn–Al alloy filler metal was used to braze 6063 Al alloys using direct-current resistance brazing. We clearly observed that EM occurred and analyzed its effect on the microstructures and morphology of joints. Al atoms migrated from the negative side to the positive side under a combined effect of the electric field and chemical gradient, while Zn atoms migrated in the opposite direction due to a back stress gradient. Further, growth of a solid solution layer at the positive side was inhibited by the back stress gradient, which also promoted growth of a similar layer at the negative side.
      PubDate: 2019-02-12
       
  • Effect of Molten Metal Temperature on Mold Filling in Evaporative Pattern
           Casting
    • Abstract: The mold filling rate during evaporative pattern casting was measured in a wide range of molten metal temperatures from 800 to 1450 °C. A polystyrene columnar foam was used as the foamed pattern, and bottom pouring was applied to design the casting. Tin alloy, copper alloy, and cast iron were used as molten metals to vary the molten metal temperature. The mold filling rate increased with increasing molten metal temperature at relatively lower temperatures. In contrast, the mold filling rate decreased with increasing molten metal temperature at high temperatures. These phenomena were verified by in situ observation.
      PubDate: 2019-02-01
       
  • Thermal Analysis and Graphitization Ability of Spheroidal Graphite Cast
           Iron Preconditioned by Al,Zr,Ca–FeSi
    • Abstract: The increasing demand for pre-pouring melt quality evaluation by thermal analysis has led to some important breakthroughs in understanding the solidification of spheroidal graphite cast iron (SGI). The two important parameters which characterize the solidification cooling curve of SGI are temperature of eutectic undercooling (TEU) temperature of eutectic recalescence (TER). In this study, the response of preconditioning treatment (0.1% Al,Zr,Ca–FeSi) on TEU and TER was investigated in several samples from different heats. It was found that preconditioning increases both TEU and TER. The average eutectic graphitization ability after preconditioning was found to increase from 60 to 75. The average undercooling (∆T) and recalescence (∆Tr) in preconditioned samples were 12 °C and 2 °C, whereas in samples without preconditioning average ∆T and ∆Tr are 19 °C and 7 °C, respectively. Preconditioning improves graphitization ability thereby increasing the graphite nodule count. The actual nodule count of SG iron samples obtained by image analysis was found to be in agreement with that of nodule counts predicted by thermal analysis.
      PubDate: 2019-02-01
       
  • Effect of Firing Temperature and Duration on Fused Silica Investment Shell
           Strength at Room Temperature
    • Abstract: Fused silica is widely used in investment casting shell molds as flour, stucco and binder for its superior properties, such as low linear thermal expansion coefficient and high thermal shock resistance. Investment shell molds are usually fired after the de-wax process to remove the residue pattern material, and to improve shell strength through sintering. The firing temperatures are generally high enough to affect the phase constituent and microstructure of the shells, which further influences the shell strength. Firing duration at firing temperature is another important factor having an impact on the shell strength due to grain coarsening, but it is often overlooked by investment foundries. In this article, the room temperature moduli of rupture of investment shells fired at different conditions were determined. The crystallinity of fused silica shells was determined using X-ray diffraction. The differences on the shell strength were discussed and correlated with the microstructure and phase constitution in the shells after different firing processes.
      PubDate: 2019-01-31
       
  • Study on Reduction in Shrinkage Defects in HPDC Component by Optimization
           of Localized Squeezing Process
    • Abstract: In high-pressure die casting component, shrinkage defects plays a major role in leakage of fluid from components; therefore, it becomes necessary to predict the exact location of the shrinkage defect to reduce its intensity to an acceptable level. Nowadays, a localized squeezing process is one of the popular ways of reducing the shrinkage defect in high-pressure die casting components. Squeeze pins can be used to compensate for shrinkage defects in these components. The main reason for the formation of shrinkage porosity at the critical location of a given component is large and poorly fed hot spot. In this paper, shrinkage defects are reduced from level III to level I by determining optimum values of squeeze pin parameters by DOE and flow simulation, obtained results are implemented in order to test and verify effectiveness of the method. An excellent agreement is indicated for the simulation result and the experimental results.
      PubDate: 2019-01-25
       
  • Biocorrosion and Mechanical Properties of ZXM100 and ZXM120 Magnesium
           Alloys
    • Abstract: In this study, as-cast Mg, ZXM100 (1.07Zn–0.21Ca–0.31Mn) and ZXM120 (1.01Zn–1.63Ca–0.30Mn) alloys were produced by gravity die casting method, and microstructure, phase analysis, corrosion and mechanical properties of the alloys were investigated comparatively in order to develop degradable Mg-based biomaterials with improved properties. It is observed that Ca2Mg6Zn3 phase is expected to be present in ZXM100 (1.07Zn–0.21Ca–0.31Mn) alloy totally dissolved in the α-Mg matrix after homogenization heat treatment. However, Mg2Ca phase is expected to be present in ZXM100 (1.07Zn–0.21Ca–0.31Mn) alloy partially dissolved in the α-Mg matrix. Results showed that ZXM100 alloy has a much more homogeneous structure, a better performance, higher corrosion resistance and mechanical properties than those of as-cast Mg and ZXM120 alloy. ZXM100 (0.099 mm/year) alloy has a three times slower corrosion rate than ZXM120 (0.294 mm/year) alloy. It is found that the ZXM100 alloy has closer values to the desired corrosion rate and mechanical properties as a biodegradable implant material.
      PubDate: 2019-01-25
       
  • Particle Method Simulation for Formation and Flow of Cold Flakes in
           High-Pressure Die Casting
    • Abstract: In high-pressure die casting (HPDC) processing of aluminum alloys, solidified layers generated in the sleeve of a die casting machine that flow into the mold cavity are known as “cold flakes.” The prediction and control of them are a crucially important issue for HPDC. This study developed a method to simulate their formation and flow using smoothed particle hydrodynamics. First, a solidified layer was modeled as a set of solid particles with behaviors defined by mechanical constitutive equations. Second, this study proposed an algorithm for ascertaining the phase of particles and for calculating liquid–solid particle interaction. Numerical results demonstrated that the method can predict the formations of solidified layers in the sleeve, their peeling and folding during the plunger movements, their inflow into the runner and the mold cavity, and flow disturbances caused by solidified layers trapped at the gate.
      PubDate: 2019-01-25
       
  • Systematical Approach for Vent Design of Core Out-Gassing Through
           Development of an Inventive Evaluation Device
    • Abstract: Casting defects caused by the core gas evolution impair the performance of a machine. The estimation of core gas evolution and core out-gassing are necessary for thin-wall high-pressure castings with complicated actual size core systems. The development of our patented device for core out-gassing made possible a systematical approach for the vent design of core out-gassing in the design stage of the core shape and the mold concepts of casting, such as engine parts with complicated core systems. Experimental procedures and analytical reviews on the relative performance evaluation of suction routes of core gas were attempted with aluminum thin-wall cylinder head casting. Also, two different distributions of particle sizes of core sand were evaluated in order to review effects of fine particle of core sand on core out-gassing. The device developed for core out-gassing in this study was composed of a chamber, a vacuum pump, pressure sensors, and a data logger.
      PubDate: 2019-01-23
       
  • Defect Susceptibility of Tensile Properties to Microporosity Variation in
           High-Pressure Die-Cast Aluminium Alloy Controlled by Gas Bubbling
           Flotation Treatment
    • Abstract: This study aims to investigate the variability in the tensile properties of high-pressure die-cast aluminium alloy controlled by the gas bubbling filtration or flotation (GBF) process in terms of the defect susceptibility of tensile properties to the variation in the overall microporosity level, including bifilm oxide and pre-existing microvoids. Test specimens were fabricated by adopting a high-pressure die-cast process of the cold chamber type at the production scale using A384.0 aluminium alloy. The volumetric porosity of cast specimens gradually decreased with GBF treatment, even though the fractographic porosity tended to decrease only under a specific GBF condition, with a remarkable microstructural refinement. The degassing treatment of 5 min could achieve a remarkable grain refinement, and further, this optimal condition could induce a practical improvement in the defect susceptibility of tensile properties to microporosity variation as well as the nominal level of tensile properties. The main reason for grain refinement in GBF treatment is the dispersion of small-sized pro-eutectic solid particles by fragmentation of abnormally big-sized dendrites, which are preferentially formed by an undercooling effect in a region around the impeller and gas inlet. Additionally, the improvement in melt quality by degassing action for dissolved hydrogen gas is practically nullified through the coarsening of pro-eutectic solid particles as well as the additional inclusion of bifilm oxide by excessive GBF treatment.
      PubDate: 2019-01-14
       
  • Feasibility of US Foundry Supply Chain Consumables for Three-Dimensional
           Sand Printing
    • Abstract: The purpose of this study was to assess the performance characteristics of commercially available US foundry consumables for use in three-dimensional sand printers. The silica sands selected were 57 grain fineness number (GFN) and 70 GFN. These sands were a high-purity round grain silica and had low trace contaminates, to reduce any possible influence from contaminates. The furan resin system was selected since it is the most widely utilized resin system for 3D printed sand in the USA. The furan resin system was from a domestic US foundry supplier. The printed samples were traditional tensile specimen and rectangle samples for the determination of density. The samples were examined for the following properties: tensile strength, loss on ignition, density, scratch hardness, and permeability. The results of this investigation confirmed that the tested domestic resin system and silica sands matched the original equipment manufacturer performance properties.
      PubDate: 2019-01-07
       
  • Technology of Alloy Layers on Surface of Castings
    • Abstract: The paper presents a technology of layered castings based on the use of a method of mould cavity preparation via spatial skeleton insert. The insert was created as a result of application of 3D printing selective laser melting method. The studied spatial skeleton insert, made from CP2 Ti powder, was placed into the mould cavity directly before pouring grey cast iron. The scope of the conducted studies covered metallographic research using a light microscope and scanning electron microscope with EDS analysis, hardness measurements and abrasive wear resistance tests. The obtained results show that the interaction between the solid spatial skeleton insert and liquid alloy allowed for the production of a casting of pearlitic grey cast iron with flake graphite, containing a surface layer reinforced with titanium carbides. In consequence, a local increase in hardness was obtained and, moreover, an increase in abrasive wear resistance of the whole surface layer of the casting.
      PubDate: 2019-01-07
       
  • The Effect of the Substitution of Silicon by Aluminum on the Properties of
           Lamellar Graphite Iron
    • Abstract: In cast iron, silicon and aluminum are elements that promote graphite precipitation and strengthen the alloy by solid solution. In the present work, Si has been substituted by Al leading to values that easily surpass standard properties of Fe–C–Si gray cast irons, reaching a strength of 466 MPa at moderate hardness (250 HB) for an iron with 3.08% C, 3.15% Al and 0.16% Si. Sequences of heats increasing Al content were carried out. It was found that the UTS increases with the Al content, reaching a maximum at about 3% Al, after which it decreases. Graphite area measurements show a minimum at the maximum UTS, with graphite exhibiting random orientation. Carbides are avoided above 1.5% Al for very low Si content (about 0.2%) in Y2 keel blocks (25 mm thickness). Plates as thin as 2.5 mm were cast free of carbides from irons with more than 3% Al, which makes this material very desirable for thin wall castings. Additions of other elements were necessary, including 0.35% chromium, 0.55% manganese and 0.075% tin to obtain a pearlitic structure.
      PubDate: 2019-01-07
       
 
 
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