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About this book

This book contains a collection of papers on the science, engineering, and technology of shape casting, with contributions from researchers worldwide. Among the topics that are addressed are the structure-property-performance relationships, modeling of casting processes, and the effect of casting defects on the mechanical properties of cast alloys.

Table of Contents

Frontmatter

Entrainment and Bifilms

Frontmatter

Update on Bifilms—The Fundamental Defect in Metals

The concept of the bifilmBifilm (BI) is now nearly 20 years old. It has been clearly shown to control structural defectsDefects in castings such as porosityPorosity and hot tearingHot tearing , plus, in solid wrought products, mechanical propertiesMechanical properties such as ductility and fatigueFatigue . It appears to explain for the first time the structures of Al–Si alloys and cast irons. Furthermore, although there are a number of proposed mechanisms for crack initiation in metals, it seems most probable that these are invalid. It follows that there is probably no intrinsic crack failure mechanism for most engineering metals; metals should never crack. The only crack-initiating feature appears to be the bifilmBifilm (BI) , introduced accidentally during castingCasting . By appropriate castingCasting techniques, the introduction of bifilmsBifilms can be avoided. For this reason, failure by fatigueFatigue and creepCreep may be eliminated, together with invasive corrosionCorrosion such as pitting, stress corrosionCorrosion cracking and possibly other failure modes.

John Campbell

Entrainment Defects in Cast Iron

Castings were made of two types of cast ironCast iron , flake grey iron (FGI) and spheroidal graphiteSpheroidal graphite iron (SGI), in test bar moulds having both turbulent and quiescent filling systems. The different filling system designs did not seem to affect the scatter of values of the ultimate tensileTensile strength (UTS) in FGI. On the other hand, the turbulently filled moulds had increased scatter of UTS values in the case of the FGI more than in the case of the SGI. Slag particles and ternary eutectic phosphide defectsDefects were identified as responsible for the fracture of FGI test bars. Two types of defectsDefects , (classified as type I and II), symmetrical on either side of the fracture surfaces of tensileTensile test bars, were found in the SGI test bars, but not the FGI test bars. Scanning electron microscopy and EDX analysis of defectsDefects suggested that type I was a thin film of magnesium silicate and type II consisted of folded-over carbon-rich films containing magnesium oxide. These defectsDefects are similar in form and structure to the double oxide film defectsDefects found in Al and Mg alloys.

Zakareya Nashwan, W. D. Griffiths

Measurement of Air Entrainment During Pouring of an Aluminum Alloy

Air entrainmentAir Entrainment during mold filling leads to oxide inclusionsOxide Inclusions that can severely diminish the mechanical propertiesMechanical properties of castings. Despite this, the volume of air that is entrained during pouringPouring of liquid metals has never been quantified. The present research focuses on air entrainmentAir Entrainment for a liquid aluminumAluminum alloy jet plunging into a pool. Experimental measurements with argon and air atmospheres are performed to determine the total volume of gas entrained during pouringPouring and the volume of oxygen consumed. They are used to validate a previously developed model that predicts air entrainmentAir Entrainment as part of a casting simulationCasting simulation . The measured entrainment ratios from the experiments conducted in an argon atmosphere are in approximate agreement with the previously developed model. A large difference between entrainment ratios for argon and air atmospheres is found.

Lucas Archer, F. V. Guerra, Christoph Beckermann

Connecting Oxide Bifilms’ Properties from Atomistic Simulations with Virtual Casting of Aluminum

AluminumAluminum oxide bifilmsBifilms , formed during melt turbulence flow, can have a significant detrimental effect on material properties after they are entrapped in the final cast products. Recently, molecular dynamics (MD) simulations were used to simulate the formation and fracture mechanisms of bifilmsBifilms at the nano-scale, which are hard to obtain experimentally. The results showed that the fracture occurred at the Al/oxide interface instead of the oxide/oxide interface for both amorphous oxide and crystalline α-Al2O3, which represent the “young” and “old” oxides referred in aluminumAluminum castingCasting . The fracture energy is higher for the α-Al2O3 bifilm. However, if OH-termination contamination occurs due to residue hydrogen gas and water trapped in the aluminumAluminum oxide bifilmBifilm (BI) interface, the OH-termination oxide bifilmBifilm (BI) fractured at the oxide/oxide interface and with a much-reduced fracture energy. This is consistent with the general picture that oxide bifilmsBifilms will initiate cracks, especially fatigueFatigue cracks in cast aluminumAluminum products. For macroscopic models, crack initiation and propagation can be modeled by cohesive zone method. Therefore, we propose a simple size bridging relationship to connect the MD-predicted oxide bifilmsBifilms fracture energy and fracture strength with future finite element modeling.

Jialin Liu, Qigui Wang, Yue Qi

Numerical Process Modelling and Simulation of Campbell Running Systems Designs

In the 1980s, John Campbell developed a new castingCasting process from his research in the industry over a number of years. The CosworthCosworth process was for delivering very high-quality aluminium components for the automotive industry. The process was very capital-intensive and not very flexible for smaller companies delivering lower volumes of product. However, the principles behind the process have been taken and used to develop a range of different so-called running systems to help improve the quality of castings. Some of these designs have been published in ‘Castings Handbook’ [1] authored by Campbell. This paper presents the results of an MSc project during which a number of the proposed designs from Campbell’s Mini CastingCasting Handbook [2] for certain features in running systems have been modelled using a validated CFD software.

Chengcheng Lyu, Michail Papanikolaou, Mark Jolly

Synchrotron X-Ray Real-Time Studies of the Nucleation and Growth of Intermetallic Phases in Solidification

In this paper, real-time, direct observation of the nucleationNucleation of primary Al2Cu phases on entrained oxide filmsOxide films during the solidificationSolidification of an Al-35%Cu alloy, and the change of growthGrowth mode from planner to dendritic type structure of Al3Ni phases in an Al-15%Ni alloy under a pulse magnetic field are presented and discussed. Real-time synchrotron X-ray radiography provides clear and unambiguous evidence to confirm that the entrained oxide filmsOxide films can indeed directly nucleate primary Al2Cu intermetallic phasesIntermetallic phases . Combining radiography and tomography together, the critical conditions of changing growthGrowth mode from a planner to dendritic type for the Al3Ni phases were also clearly revealed. The research demonstrates that synchrotron X-ray-based real-time characterisation techniques are the indispensable tools for quantitative solidificationSolidification research.

Jiawei Mi

Determination of Liquid Metal Quality with Deep Etching Method

In this study, the deep etchDeep etch method was applied to Al–Si castingCasting alloys in order to visualize the presence of the bifilmsBifilms . Reduced pressure test was used to quantify the bifilmsBifilms in the melt. The cross section of the RPT samples was subjected to deep etching with H2SO4, HNO3, NaOH, and NaCl solutions at various temperatures and concentrations. The aim was targeted to etch the matrix and reveal bifilmsBifilms on these surfaces. Additionally, the oxide structure on the surface of cast specimens was altered by treatment at 500 °C for 8 h. One half was ground, and these samples were subjected to deep etching again in the same conditions. It was found that bifilmsBifilms were dissolved after 5 min of deep etching in HNO3, H2SO4, NaCl, and NaOH solutions.

Furkan Tezer, Özen Gürsoy, Eray Erzi, Mert Zorağa, Derya Dışpınar

Effect of Fe-Rich Intermetallics on Tensile Behavior of Al–Cu 206 Cast Alloys at Solid and Near-Solid States

Iron is one of the most common impurity elements in Al–Cu 206 cast alloys as it often causes the precipitation of Fe-rich intermetallic phasesIntermetallic phases during solidificationSolidification due to its extremely low solid solubility in aluminumAluminum . The characteristics of the Fe-rich intermetallicsFe-rich intermetallics , such as type, morphology, size, and distribution, have significant influences on the tensileTensile behaviors of the Al alloysAl alloys . In the present work, two Al–Cu 206 cast alloys containing different types of Fe-rich intermetallicsFe-rich intermetallics (dominated by either platelet β-Fe or Chinese script α-Fe) were cast and their tensileTensile tests were performed at both solid (room temperature) and near-solid (2.8 vol. % liquid) states. It is found that the tensile propertiesTensile properties in both solid and near-solid states are improved when the Fe-rich intermetallicsFe-rich intermetallics change from platelet to Chinese script morphologies. During the solid-state tensileTensile deformation, the failure occurs mainly along the platelet β-Fe intermetallics/Al matrix interface or within the Chinese script α-Fe particles. In the near-solid state, the alloy containing mainly Chinese script α-Fe is found to have more free flow paths for liquid feeding, leading to improved tensile propertiesTensile properties . By contrast, the platelet β-Fe can cause the blockage of the liquid flow paths, leading to the degraded tensile propertiesTensile properties and worsened susceptibility to hot-tearingHot tearing .

K. Liu, X. Cao, A. Bolouri, X.-G. Chen

Casting Defects and Their Characterization

Frontmatter

Determining Casting Defects in Thixomolding Mg Casting Part by Computed Tomography

A quantitative analysis on the casting defectsCasting defects is of great necessity to further improve the mechanical propertiesMechanical properties of high-performance alloys, in particular dynamic fatigueFatigue properties. Computed tomographyComputed tomography (CT) is frequently utilized to determine the casting defectsCasting defects of castingCasting parts and thereby evaluate their castingCasting qualities. In this contribution, one Mg castingCasting part (AZ91D, Mg–9Al–1Zn) produced by thixomoldingThixomolding was investigated by computed tomographyComputed tomography . No significant castingCasting defectDefect was observed, strongly indicating that thixomoldingThixomolding could produce high-quality Mg castingCasting parts. Furthermore, newly developed reconstruction software developed in Austria (VrVia GmbH) was used to obtain more details from the same castingCasting part. This investigation demonstrates that computed tomographyComputed tomography is an efficient method to determine casting defectsCasting defects in near-net-shape castingShape casting parts.

Jiehua Li, Bernd Oberdorfer, Peter Schumacher

The Effect of the Addition of Transition Metals on Double Oxide Film Defects in an Al–Si–Mg Alloy

Double oxide film defectsDefects (bifilmsBifilms ) are associated with a reduction in mechanical propertiesMechanical properties in Al and Mg alloys, but also with a variability in mechanical propertiesMechanical properties that is difficult to compensate for when designing castings. This paper reports the effect of the addition of 0.45 wt% Mo, or of 0.45 wt% W, to an Al-7Si-0.3 Mg aerospace and automotive alloy. The additions resulted in an increase in the WeibullWeibull modulus of the UTS (i.e. a reduction in the scatter of the measured mechanical property data), by a factor of about two (about from m = 16 to m = 32). The observation of AlN on the fracture surfaces of some tensileTensile test bars suggests the additions of Mo or W were associated with the acceleration of the reaction between the oxygen and nitrogen in the internal atmosphere of the double oxide defectsDefects and the surrounding liquid metal. This may alter the morphology of the defectsDefects , reducing their size and reducing their impact of mechanical propertiesMechanical properties . The greatest improvement in reproducibility of tensile propertiesTensile properties (UTS) was obtained when an addition of 0.45 wt% W was coupled with a well-designed running system, resulting in a WeibullWeibull modulus of m = 96.

W. D. Griffiths, A. J. Caden, Q. Chen

On Estimating Largest Defects in Castings

The procedure developed by Beretta and Murakami has two issues that were not addressed previously: (i) the selection of the WeibullWeibull plotting position formula for linear regression fits to estimate GumbelGumbel distribution parameters and (ii) the untested hypothesis that the estimates for the upper GumbelGumbel percentiles are distributed normally. Monte Carlo simulations were run to determine the plotting position formula that provided the least bias and the distribution of GumbelGumbel percentiles. It was found that among the nine formulas used in this study, the one developed by Hazen had the least bias, whereas the one by WeibullWeibull had the highest bias. Moreover, 0.999 percentiles of the GumbelGumbel distribution were found to follow the three-parameter lognormal3-parameter lognormal distribution. Empirical relationships between the estimated parameters of the three-parameter lognormal3-parameter lognormal distribution and sample size are provided in the paper.

Murat Tiryakioğlu, Irisi Nini

Ti Grain Refinement Myth and Cleanliness of A356 Melt

Grain refinementGrain refinement of cast alloys provides several advantages such as establishment of finer dendritic structure, lowered porosityPorosity due to increased feeding, and thereby higher mechanical propertiesMechanical properties are reached. For Al–Si alloys, TiTi is the preferred; however, Ti has the tendency to sink to the bottom of the crucible due to density difference. In this work, this phenomenon was used to evaluate the correlation of TiTi nucleationNucleation on bifilmsBifilms and thereby sedimenting the defectsDefects to clean the melt. Primary and secondary A356A356 alloys were used. After grain refinementGrain refinement addition, samples were collected every 10 min to investigate the change in melt qualityMelt quality . Sand and die moulds were used. TensileTensile samples were produced for mechanical characterisation. Step mould was used to check the microstructural changes. Reduced pressure test was used to quantify melt cleanlinessCleanliness . It was found that melt qualityMelt quality was increased by duration. Mechanical propertiesMechanical properties were increased regardless of the microstructureMicrostructure .

Özen Gürsoy, Eray Erzi, Derya Dışpınar

On the Effects of Defects and Imperfections on Tensile Toughness of a Secondary Aluminium Alloy

In order to design and produce high-quality castings with reliable performance, the effect of the melt handling and melt qualityMelt quality during different processing stages needs to be understood and controlled, and numerical methods to provide correct input data to structural analyses of castings enabled. This paper aims to investigate tensile propertiesTensile properties , in particular tensileTensile toughnessToughness , of a secondary high-pressure die castingHigh pressure die casting (HPDC) aluminium alloy with different levels of defectsDefects and imperfections. The melt, which was transported in liquid state from the smelter to the foundry, has been sampled after different holding times by castingCasting into Y-blocks. TensileTensile testing was performed, and the levels of defectsDefects and imperfections were characterized using measurements of porosityPorosity , bifilmBifilm (BI) index, density index, sludge factor and the amount of iron-rich intermetallics. Two different quality indices have been evaluated, and a method to apply the results in simulations of damage in a castingCasting , containing defectsDefects , subjected to load is demonstrated.

Jakob Olofsson, Anton Bjurenstedt, Salem Seifeddine

The Myth of Hydrogen Pores in Aluminum Castings

The equilibrium solubility of hydrogen in liquid and solid aluminumAluminum is reviewed. Homogeneous and heterogeneous nucleationNucleation of hydrogen as pores are evaluated. It has been determined that homogeneous nucleationNucleation of hydrogen pores is impossible. Moreover, in situ observations of pore formation in melts with high hydrogen contents are inconsistent with heterogeneous nucleationNucleation of hydrogen pores. The only mechanism for hydrogen to contribute to pore formation is the inflation of bifilmsBifilms by diffusion. Hence, in the absence of bifilmsBifilms in the melt, measuring and controlling hydrogen content in the melt would be unnecessary.

Murat Tiryakioğlu

Casting Defect Analysis on Fracture Surface of 356 Aluminium Alloy

Investigation of the fracture surfaceFracture surface is an effective method in characterizing casting defectsCasting defects . Some data can be collected such as the population of defectsDefects and initiation of fracture by means of investigation of fracture surfaceFracture surface via a scanning electron microscope (SEM). In this study, tensileTensile test samples from two different 356 aluminium melts that have good and quite bad quality were poured into die and sand moulds under two different conditions: no addition and Al–Ti–B grain refiner addition. After the tensileTensile test, casting defectsCasting defects in fracture surfaces are analysed and classified via SEM. The area fraction of defectsDefects (AFD) is created and correlated with bifilmBifilm (BI) index and tensile propertiesTensile properties such as UTS and elongation.

Özen Gürsoy, Eray Erzi, Derya Dispinar

Investigation of Casting Quality Change of A356 by Duration in Liquid State

This study aims to investigate how casting qualityCasting quality change in aluminumAluminum melt during the holding period in liquid state. 10 kg of ingot was melted in a SiC crucible by using an electrical furnace. A sample was taken every five minutes from 0 to 55 min after the alloy was melted. Reduced pressure test (RPT) samples were collected to be solidified under 80 mbar. All samples were sectioned into two parts vertically, and one of them was prepared for metallographic examination. Surface of the samples was subjected to image analysis by using via image analysis software. Bifilm indexBifilm index and bifilmBifilm (BI) area were analyzed in detail. As a result, it can be concluded that first 30 min of liquid metal is important, because casting qualityCasting quality tends to get worse after 30 min.

Muhammet Uludağ, Mikdat Gurtaran, Derya Dispinar

Characterization of the Effect of Sr and Ti on Liquid Quality in Al8Si3Cu

Al8Si3Cu alloyAl8Si3Cu alloy was studied to investigate the effect of castingCasting conditions on melt qualityMelt quality of the molten metal. While Sr and Ti master alloys were used as additional parameters, holding timeHolding time was performed for effect of held liquid. Experimental study was tried before and after degassingDegassing . The reduced pressure test machine was used to produce samples which are five samples for each parameter. Samples were prepared by metallographic methods to be analyzed with via digital image processing. Pores on the surface of the samples were measured in number density and distribution of them was examined statistically. Results showed that while Sr addition and holding timeHolding time increased casting defectsCasting defects by increasing porosityPorosity , degassingDegassing decreased the number density of defectsDefects , as expected. Therefore, it is a vital result that degassingDegassing process must be applied to every castingCasting . In addition, Ti addition was found to have a slight positive effect to reduce porosityPorosity , but it was almost negligible when compared to that of degassingDegassing process.

Muhammet Uludağ, Derya Dispinar, Murat Tiryakioğlu

Process Innovation and Modelling

Frontmatter

The Nemak Cosworth Casting Process Latest Generation

This current paper provides an update to the well-known CosworthCosworth CastingCasting process. This paper revisits results first reported in 2009 and compares them with the latest generation of innovations that have further improved castingCasting performance for 2019 model year engines. Traditionally only the main bearing saddle areas of the cylinder blockCylinder Block castingCasting were targeted for enhanced solidificationSolidification via integral chilling elements. In this latest evolution, mechanical propertiesMechanical properties of other areas of the castingCasting have further been enhanced and result in a complete solution for high-performance diesel and gasoline cylinder blockCylinder Block castings.

Glenn Byczynski, Robert Mackay

Campbellology for Runner System Design

The runner systems based on the Campbellology, the 10 castingCasting rules of Professor John Campbell, were designed to achieve the bifilmBifilm (BI) -defect Defect free casts during the filling process in gravity castingGravity casting . In this study, three main methods were utilized to control the bottom-gating velocity under the critical velocity (the rule no. 2). In these methods, the kinetic energy form of liquid metal (with high velocity) was transformed to the static pressure form (under the critical velocity) in the bottom of the gating systems. The total head height with low energy loss was maintained in these runner designs. A continuous and positive static pressure of liquid metal against to the wall of mold cavity from the bottom to the top of cast was accomplished throughout the filling. Many design schemes to avoid the filling defectsDefects , such as oxide entrapment, confluence weld, bubble entrainment, and sand core blow defectsDefects , were also suggested in these castingCasting processes.

Fu-Yuan Hsu

A Solidification Model with Application to AlSi-Based Alloys

The behavior of a cast component under service conditions depends primarily on its local microstructural features, such as the amount and morphology of phases and chemical compounds precipitating during the solidificationSolidification process. Therefore, developing a good understanding between the influencing factors (chemical composition of the alloy and cooling conditions) and the solidificationSolidification path is of great importance for establishing the castingCasting process conducive to desired results. Because the solidificationSolidification path of commercial AlSi-based alloys is quite complex, predictive capabilities for this type of alloys have been developed and incorporated into the commercial casting simulationCasting simulation software FLOW-3D® CAST. Models for quantitative description of the precipitation reactionsPrecipitation reactions , their temperature range, precipitation rate of phases and compounds, as well as the secondary dendrite arm spacingDendrite arm spacing in relation to the chemical composition and cooling conditions are presented in this chapter. Comparisons of predicted microstructureMicrostructure with experimental measurements on a test castingCasting are also discussed.

Adrian V. Catalina, Liping Xue, Charles A. Monroe

Physical Modeling of Transport Phenomena in Asymmetrical Multi-strand Tundish with Retaining Wall

In multi-strandMulti-strand tundishTundish , the structure is more complex and has various types compared with single/double-strand tundishTundish and the horizontal distance between ladle shroud and each submerged nozzles is much different which leads to the inhomogeneity between each outlets. In this paper, physical simulationPhysical simulation was conducted in a full-scale physical model of asymmetrical multi-strandMulti-strand tundishTundish to study the effect of the direction of the diversion hole on the retaining wallRetaining wall on tundishTundish performance. The optimized retaining wallRetaining wall is applied to field production, and industrial experiments were conducted to analyze the effect of inclusion removal before and after optimization. The effects were quantified by measuring residence time of fluid in the tundishTundish . According to the results, the optimized retaining wallRetaining wall improved the homogeneity between each outlets and enhanced the metallurgical function of the tundishTundish .

Wei Xiao, Yanping Bao

The Validation of Feeder Modeling for Ductile Iron Castings

A precise feeder designFeeder design for a ductile iron castingCasting is difficult, due to the complexities of its liquid–solid states transformation. During solidificationSolidification , a negative pressure in castings is developed from the volumetric shrinkage as liquid iron solidified, while a positive pressure is added from the volumetric expansion as spheroidal graphiteSpheroidal graphite crystallized from the liquid iron. A unique crystalline structure of Austenite shell surrounds the spherical graphite and also increases the viscosity of feeding fluid flow. First principle model was applied for modeling the flow behavior of the residual liquid iron during solidificationSolidification . The phenomenon of volumetric expansion as spheroidal graphiteSpheroidal graphite crystallized was also considered. The model was validated by real castingCasting a cube-shaped cast. The predictions of the shrinkage area and porosities were confirmed by the hardnessHardness contours in the cross-sectional area of the castings. An optimized solidificationSolidification modulus ratio of the feeder to this cube cast was suggested.

Fu-Yuan Hsu, Yu-Hung Chen

The Contactless Electromagnetic Sonotrode

Ultrasonic pressure waves generated using a tuned electromagnetic induction coil promote cavitation in alloy melts as an alternative to the immersed sonotrode technique. The method targets the same benefits offered by traditional UST (degassingDegassing , microstructureMicrostructure refinement, dispersion of particles), but without some of its drawbacks. The method is contactless, meaning it can be applied equally to high temperature/reactive melts, avoiding contamination due to probe erosion, and consequently, it is maintenance free. Due to induction stirring, larger volumes of melt can be treated (a major limitation of the traditional method), as the liquid is forced to pass repeatedly through zones of cavitation activity. The coil configuration used will depend on application. In the installation shown, a top conical coil immersed in aluminium melt (contactless due to EM repulsion) was used. Simulations of sound, flow and EM fields are given, compared with experiments and indicating strong stirring, evidence of cavitation through emitted sound signals and, most importantly, grain refinementGrain refinement .

Koulis A. Pericleous, Valdis Bojarevics, Georgi Djambazov, Agnieszka Dybalska, William Griffiths, Catherine Tonry

Simulation Analysis Techniques for Investment Casting Process of Ni-Base Superalloy Components

Development of the Ni-base single crystal (SC) superalloy, named MGA1700 (TMS-1700), has been carried out in a collaborative research between National Institute for Materials Science (NIMS) and Mitsubishi Heavy Industries (MHI). Besides the excellent creepCreep strength and dwell thermo-mechanical fatigueFatigue strength, the newly developed alloy for high-efficiency gas turbine blade has no expensive elements such as Rhenium. On the other hand, the mechanical propertiesMechanical properties or manufacturing yield of SC superalloy blades is quite sensitive to castingCasting process conditions. Therefore, in this study, simulation analysis techniques for various steps of investment castingInvestment Casting process, including the solidificationSolidification process and the mold manufacturing process, have been established to find adequate castingCasting conditions. These analysis techniques can be also applied to other components, such as directionally solidified (DS) rotating blade or conventional castingCasting (CC) rotating blade/stationary vane.

Kosuke Fujiwara, Hidetaka Oguma, Masaki Taneike, Ikuo Okada, Kyoko Kawagishi, Tadaharu Yokokawa, Hiroshi Harada

Improvement in Metallurgical Properties of Gravity Die Cast 2024-T6 Aluminum Alloy via Cryogenic Process

The aim of this study is to investigate the effects of cryogenicCryogenic process (CP) on the properties of 2024-T6 aluminumAluminum alloy. So, samples were held at −40 °C medium for 24 h in CP after solution heat treatment. Finally, samples were subjected to aging process at 120 °C for 8 h after CP. Furthermore, aging process was carried out after 0, 1, and 4 h later after CP. Examination of microstructureMicrostructure was executed by SEM, EDS, and optical microscope (OM) observations. HardnessHardness tests were also conducted through HV. Improvement in metallurgical properties of 2024-T6 aluminumAluminum alloy was tested with these parameters, in detail.

Engin Tan, Sinan Aksöz, Yavuz Kaplan, Hilal Can, Derya Dışpınar

Melt Cleaning Efficiency of Various Fluxes for A356 Alloy

DegassingDegassing operations are common methods to remove inclusions and oxides from the melt. In many occasions, fluxes are used through the melt in order to increase efficiency of oxide removal. In this work, a dirty melt was prepared by means of adding 50 wt% swarf to primary A356 alloyA356 alloy . Fluxes with various ratios of NaCl–KCl and MgCl2–KCl salts were prepared. Different weight ratio of Na3AlF6 and AlF3 was added. Melt cleanlinessCleanliness was measured by means of change in bifilmBifilm (BI) index (ΔBIBifilm (BI) ) before and after degassingDegassing . It was concluded that most of the fluxes had cleaning efficiency below 40% while MgCl2 based fluxes had over 70% cleaning effect.

Çağlar Yüksel, Uğur Aybarc, Eray Erzi, Derya Dispinar, Mustafa Cigdem

Properties of Castings

Frontmatter

Characterisation of Lead Sheet Manufactured Using Traditional Sand-Casting Technique

Lead sheetLead sheet is widely used for roofing and flashing applications. Continuous castingCasting and rolling are the most common processes used for manufacture of such sheet. Sand castingCasting of lead sheetLead sheet is a traditional process used since the Romans. Sand cast lead sheetLead sheet is presently used for restoration of heritage buildings, churches and cathedrals. It possesses a distinct texture due to the uniqueness of the manufacturing process and is considered a premium product. In the present study, sand cast lead sheetLead sheet samples were collected and characterised. The observations are then compared with characteristics of continuously cast lead sheetLead sheet obtained from the literature and are reported in this paper.

Arun Prabhakar, Konstantinos Salonitis, Mark Jolly

On the Intrinsic and Extrinsic Microstructure-Property Effects in Cast Aluminum Alloys

The metallurgy of cast aluminumAluminum alloys has been thought to be different from that of wrought alloys. It has been widely accepted that mechanical propertiesMechanical properties are controlled by dendrite arm spacingDendrite arm spacing , the presence of Fe-bearing particles, and the size of Si particles in Al–Si alloys, which fracture and debond during deformation, leading to premature failure. Whether these effects are intrinsic or mere correlations because of the structural quality of the castings is questioned in this study. By comparing with ideal properties, it is shown that the effect of dendrite arm spacingDendrite arm spacing on elongation, precipitation, and subsequent fracture of β-Al5FeSi plateletsΒ-Al5FeSi platelets and finally Si particle fractureSi particle fracture and debondingDebonding are all extrinsic.

Murat Tiryakioğlu

Measurement of Residual Strain in the Cylinder Bridge of High-Pressure Die Cast A383 Engine Blocks Using Neutron Diffraction

This article describes the use of neutron diffraction to measure residual strains in high-pressure die castDie Cast aluminumAluminum alloy engine blocks. High-pressure die castingHigh pressure die casting is widely used to manufacture aluminumAluminum alloy components for automobile applications such as engine blocks. Thermal gradients during this process can generate residual strain and stresses and may cause premature failure during service. Neutron diffraction can be used to measure the residual stress distributions deep inside large castings, as neutrons have much larger penetrating power than X-rays. In this work, neutron diffraction was used to measure the residual strain (in the axial and hoop directions) in the cylinder bridge region of high-pressure die castDie Cast A383 engine blocks in as-cast and heat-treated conditions. The results suggest that the residual strain in the cylinder bridge is tensileTensile in both the axial and hoop components for both as-cast and heat-treated engines. The residual strain in hoop direction is higher than the strain in axial direction. Residual strain in axial and hoop directions is relaxed after heat treatment.

T. Liu, L. N. Brewer, Jeffrey R. Bunn, Chris M. Fancher, L. Nastac, V. Arvikar, I. Levin

Relation Between Microstructure and Tensile Properties of V and B Added Al-7Si Alloy

It is known that vanadiumVanadium and boronBoron elements are used as grain refiners. In this study, it was aimed to increase the mechanical propertiesMechanical properties of A356A356 by grain refinementGrain refinement . BoronBoron and vanadiumVanadium elements were added in an amount of 0.05 wt% and 0.1 wt%. Al–10 V and Al–3B master alloys were used. The melts were casted into sand and permanent molds at 730 °C. The cast samples were investigated by several tests: metallographic examination for microstructureMicrostructure and porosityPorosity measurements, tensileTensile tests, and hardnessHardness tests for mechanical property characterization. Additionally, bifilmBifilm (BI) index was examined by reduced pressure test (RPT). The effect of alloying elements on the distribution, size, and shape of porosities has been determined. WeibullWeibull analysis was used. In both V and B additions, sand castings with larger grain size revealed higher and more reliable tensileTensile values than permanent castings.

Özkan Kesen, Ahmet Can Filiz, Selim Temel, Özen Gürsoy, Eray Erzi, Derya Dispinar

The Effect of Friction Stir Processing on Bifilms and Structural Quality in A356 Alloy Castings

The effect of friction stir processing (FSP) on the structural quality was tested in two A356 alloyA356 alloy ingots: conventional and continuously cast. Reduced pressure tests and microstructural analysis showed that the initial quality and microstructureMicrostructure in the two ingots were significantly different. The structural quality, as measured by the quality indexQuality index QT, of the conventional ingot improved with each FSP pass, whereas that of the continuously cast ingot went up after the first pass and remained essentially constant with additional passes. The contribution of microstructural refinementMicrostructural refinement as a result of FSP on the improvement of structural quality remains unknown. However, the largest contribution comes from bifilmsBifilms breaking up during the friction stir process.

Nelson Netto, Murat Tiryakioğlu, Paul D. Eason, Boğaçhan Őndeş, Eray Erzi

Effect of Copper and Nickel Addition on Mechanical Properties of A356 Alloy and Assessment of Mechanism of Pore Formation

In this study, changes in mechanical propertiesMechanical properties and hot tearingHot tearing properties were investigated by adding 0.2 wt% Ni and 2 wt% Cu to Al–Si–Mg alloyMg alloy . In addition, the porosityPorosity formation with regard to liquid metal cleanlinessCleanliness was investigated. CastingCasting experiments have been carried out in certain compositions. The melt was degassed and up-gassed slowly. Micro100 alloy was added to the melt to investigate the effect of the distribution of porosityPorosity on the mechanical propertiesMechanical properties . A ring permanent mould was used to test the hot tearingHot tearing characteristic and a tensileTensile test bars were poured into permanent mould to test the mechanical properties.

Kerim Yildirim, Johannes Brachmann, Derya Dispinar, Andreas Bührig-Polaczek, Uwe Vroomen

Aluminum Alloy with High Mg Content: Casting Studies for Microstructural Evolution, Phase Formation and Thermophysical Properties with Different Alloying Elements

Global strategy for material science in the automotive industry is to use the lightweight material. In the present work, the castingCasting of aluminumAluminum alloy with high magnesium content has been performed with the addition of B, Sr, Ti and Zr. Gravity sand castingGravity sand casting and permanent mold castingCasting methods were used. Microstructural evolution has been studied along with phase formations during solidificationSolidification . Microstructural changes of each alloying element have been observed via optical and SEM microscopy. XRD analysis has been done for evaluation of phase formations. TGA analysis has been done to evaluate thermos physical properties. The reduced pressure test was carried out to quantify melt cleanlinessCleanliness and bi-filmBifilm (BI) content. Indentation tests were carried out, and a linear relationship was found between mechanical test results and bi-filmBifilm (BI) index.

Armagan Gul, Özen Gürsoy, Eray Erzi, Derya Dispinar, Eyup Kayali

Correlation Between Melt Quality and Machinability of Al9Si3Cu HPDC Alloy

High-pressure die castingHigh pressure die casting is the most suitable method for mass production of Al–Si alloys. The cast parts are typically subjected to machining for the final finish. In this work, the cutting toolCutting tool life was investigated with regard to the melt qualityMelt quality . The melt cleanlinessCleanliness is defined by reduced pressure test and bifilmBifilm (BI) index was measured. Since bifilmsBifilms are oxides, the tool life can significantly be affected by the presence of bifilmsBifilms in the cast part. The study was carried out with four different melt cleanlinessCleanliness . Sixteen cutting tools were changed after 10000 parts for the castings with bifilmBifilm (BI) index higher than 200 mm. When bifilmBifilm (BI) index was decreased to 20 mm, the tool life was increased to an average of 4500 parts and totally four cutting tools were changed in 12000 parts.

Ibrahim Halil Kalkan, Omer Vardar, Ibrahim Göksel Hızlı, Eray Erzi, Ozen Gürsoy, Derya Dışpınar

Change in Sr Modification by Duration and Its Effect on Mechanical Properties of A360 and A413 Alloy

Strontium modification has many advantages for the mechanical properties of Al–Si alloys. Holding timeHolding time is an important factor in Sr modificationSr modification . Its high affinity to oxygen may result in forming of $$ {\text{SrO}}.{\text{Al}}_{2} {\text{O}}_{3} $$ SrO . Al 2 O 3 spinel oxides. Therefore, Sr quantity in the melt can decrease by time due to fading. In this work, this phenomenon was investigated in A360A360 and A413A413 alloys under different castingCasting conditions. The melt was held at 700 °C for 4 and 17 h after the addition of 300 ppm Sr. Metallographic examination was carried out to observe the change in eutectic morphology. Melt qualityMelt quality change was measured by means of reduced pressure test. In addition, tensileTensile test samples were produced. It was found that there is a clear correlation between mechanical properties and bifilmBifilm (BI) index of Al–Si alloys.

Inal Kaan Duygun, Ozen Gursoy, Eray Erzi, Derya Dispinar

Poster Session

Frontmatter

Aluminum Matrix Graphene-Reinforced Composite Materials

In this study, due to the enhanced properties of grapheneGraphene , it was aimed to produce aluminumAluminum matrix compositeComposite by grapheneGraphene reinforcement. Several different methods were applied such as lost foam castingCasting , sand castingCasting , die castingCasting , ceramic mold castingCasting and squeeze castingCasting . The incorporation of the grapheneGraphene was established by only squeeze castingCasting method. GrapheneGraphene was added by two methods: as layers and in aluminumAluminum foils. The produced samples were subjected to bending tests, and it was found that 25% increase in bending strength was achieved by 0.1 wt% grapheneGraphene addition to A356 alloyA356 alloy .

Okan Aydın, Aziz Kocaveli, Özen Gürsoy, Eray Erzi, Derya Dışpınar

Influence of Melt Quality on the Fluidity of AlSi12Fe

The usage of secondary aluminumAluminum has a large volume in the industry due to the economic benefits. The effect of degassingDegassing on the melt qualityMelt quality , microstructureMicrostructure , and mechanical propertiesMechanical properties of secondary alloys was studied in this article. FluidityFluidity and melt qualityMelt quality are having important roles on mold filling. FluidityFluidity was examined with new design mold, and melt qualityMelt quality was determined by bifilmBifilm (BI) index (BIBifilm (BI) ) via using reduces press test (RPT). In summary, the relationship between melt qualityMelt quality , mechanical propertiesMechanical properties , and fluidityFluidity has been investigated. Inverse ratios were observed between bifilmBifilm (BI) index and fluidityFluidity distance. The aspect ratio is constant at all parameters. DegassingDegassing was sufficient to increase the fluidityFluidity .

İbrahim Göksel Hızlı, Meltem Salkır, İbrahim Halil Kalkan, Derya Dışpınar

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