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Showing 43 results for Casting

Babaei R., Varahram N., Davami P., Sabzevarzadeh A.,
Volume 1, Issue 2 (6-2004)
Abstract

In this investigation, ^5 2-D Finite Volume Method (FVM) with unstructured triangular mesh is developed to simulate the mould filling process. The simulation of fluid flow and track of free surface is based on the Marker And Cell (MAC) technique. This technique has capability ofhandling the arbitrary curved solid boundaries in the casting processes. In order to verify the computational results of the simulation, a thin disk plate with transparent mould was tested. The mould filling process was recorded using a 16mm high-speed camera. Images were analyzed frame by frame, in order to tracking of free surface and filling rate during mould filling. Comparison between the experimental method and the simulation results has shown a good agreement.
Saghi S., Divandari M., Kharazi Y.h.k.,
Volume 1, Issue 2 (6-2004)
Abstract

The effects of gating system and pattern geometry on the metal flow in the lost foam casting (LFC) process have been investigated using glass covered mold and video recording system. Unlike convectional casting process, the type of the gating system showed little effect on fillability in lost foam, but pattern thickness had large effect on mold filling. The mold filling behavior seems to be controlled by the combined influences of heat and mass transfer. The flow rate increased with increasing pattern thickness.
Mirbagheri S.m.h., Ashouri H., Varahram N., Davami P.,
Volume 1, Issue 2 (6-2004)
Abstract

In this investigation a new model was developed to calculate gas pressure at the melt/foam interface (Gap) resulting from foam degradation during mould filling in the Lost Foam Casting (LFC) process. Different aspects of the process, such as foam degradation, gas elimination, transient mass, heat transfer, and permeability of the refractory coating were incorporated into this model. A Computational Fluid Dynamic (CFD) code was developed based on the numerical technique of the SOLution Algorithm- Volume Of Fluid (SOLA- VOF) utilizing model, for the simulation and prediction of the fluid flow in the LFC process. In order to verify the computational results of the simulation, a thin plate of gray iron was poured into a transparentfoam mould. The mould filling process was recorded using a 16mm high-speed camera. Images were analysed frame by frame, in order to measuring foam depolymerization rate and the gap volume during mould filling. Comparison between the experimental method and the simulation results, for the LFC filling sequence, has shown a good agreement.
Javadpour J., Sakhaii K., Masihiyanpour A.a.,
Volume 1, Issue 4 (12-2004)
Abstract

Thin sheets of hydroxyapatite were fabricated by tape casting process. The non-aqueoustape casting formulation was optimized by adjusting the concentration of organic additivesspecially those of binder and plasticizer in the slurry. The optimized slurry was cast on a glasscarrier using a designed laboratory scale doctor blade. Following a binder removal stage, thetapes were sintered at different temperatures in air atmosphere. Heat treatment at 1250 °C led tothe formation of a dense microstructure as was evidenced by the scanning electron microscopy.
Attar E., Babaei R., Homayonifar P., Asgary K., Davami P.,
Volume 1, Issue 4 (12-2004)
Abstract

During mold filling, molten metal can only advance as quickly as the air inside thecavity is expelled. In this work an analytical model describing air flow is developed based on aincompressible flow theory. Air pressure has serious effects upon the filling behaviour such assurface profile and filling time. In this work a new mathematical model is proposed for calculationthe air pressure during the mold filling. A single phase computational fluid dynamic code based onthe SOLA-VOF algorithm used for prediction the fluid flow. Air discharged through the vents ismodelled by ideal gas assumption, conservation of mass equation and Bernoulli law. A newalgorithm was developed to interpolates the air pressure on the surface cell. The creation of airback pressure was correlated with sizes of vents and pouring basin height. In order to verify thecomputational results a series of experimental test was conducted. Comparison between theexperimental data and simulation results has shown a good agreement.
Kharazi Y.h.k., Divandari M.,
Volume 2, Issue 1 (3-2005)
Abstract

The mold-filling behavior in the casting of aluminum alloy (A413) using lost foam casting (LFC) was explored. The effects of gate numbers, type of gating and casting thickness on the filling behavior were evaluated. Although, unlike convectional casting process, the gating system showed little effect onfilling ability, casting thickness created a greater effect on the mold filling. In contrast with convectional casting process, the mold filling seems to be controlled by castinggeometry as a consequence of combined influence of heat and mass transfer. The melt used to enter from the first gate instead of last gate which is in contrast with convectional casting process.
Aneziris C.g., Borzov D., Schmidt G.,
Volume 2, Issue 1 (3-2005)
Abstract

Improved structures of MgO carbon bonded materials due to new binder systems and due to the application of electrical currents during operation have been achieved for advanced applications in the secondary metallurgy and during near net shape metal casting.
Arabi H., Divandari M., Hosseini A.h.m.,
Volume 3, Issue 3 (12-2006)
Abstract

In this research the influence of Ti contents on the amounts of inclusions formation and mechanical properties of a high alloy high strength steel, C300, has been investigated. For this purpose several bars were casted under the same solidification conditions, but different amounts of Ti element. All the seven casted bars were homogenized at 1200°C for a period of 2 hours. Then, they were immediately hot rolled after homogenization so that the out rolling temperature was kept in the range of 1000-1200° C. The specimens were then solution annealed at 820°C for hour and finally they were aged for a period of 3 hours at 500°C. The samples were subjected to tensile, impact and hardness tests in order to relate the variation in volume percent of inclusions due to different amount of Ti, to mechanical properties. The results showed that by increasing the amount of Ti a serious decline in toughness properties of the alloy due to increase in inclusion population occurred. So this research provides a very useful information about the relation between volume fraction of inclusions and mechanical properties of a C300 high strength steel.
Babaei R., Shahinfar S., Homayonifar P., Dadashzadeh M., Davami P.,
Volume 3, Issue 3 (12-2006)
Abstract

In the present study a Finite Difference Method has been developed to model the transient incompressible turbulent free surface fluid flow. A single fluid has been selected for modeling of mold filling and The SOLA VOF 3D technique was modified to increase the accuracy of simulation of filling phenomena for shape castings. For modeling the turbulence phenomena k-e standard model was used. In order to achieve an accurate model, solving domain was discrete to three regions includes: laminar sub layer, boundary layer and internal region. This model was applied to experimental models such as a driven cavity, Campbell benchmark [1] and top filled cavity. The results show that the suggested model yield favorable predictions of turbulence flow and have a good consistency in comparing with experimental results.
M. Divandari,, H. Arabi, H. Ghasemi Mianaei,
Volume 5, Issue 3 (9-2008)
Abstract

Abstract: Thermal fatigue is a stochastic process often showing considerable scatter even in controlled environments. Due to complexity of thermal fatigue, there is no a complete analytical solution for predicting the effect of this property on the life of various components, subjected to severe thermal fluctuations. Among these components, one can mention car cylinder, cylinder head and piston which bear damages due to thermal fatigue. All these components are usually produced by casting techniques. In order to comprehend and compare the thermal fatigue resistance of cast Al alloys 356 and 413, this research was designed and performed. For this purpose, several samples in the form of disc were cast from the two alloys in sand mould. The microstructures of the cast samples were studied by light microscopy in order to choose the samples with the least amounts of defects for thermal fatigue tests. The results of thermal fatigue tests showed that the nucleation of microcracks in Al-356 alloy occurred at shorter time relative to those occurred in Al- 413 alloy under the same test conditions. In addition, the density of micro-cracks in Al-356 alloy was more than that of Al-413 alloy. The results of fractography on 356 alloy indicated that the cracks were generally nucleated from inter-dendritic shrinkage porosities and occasionally from the interface of silicon particles with the matrix. The growth of these micro cracks was along the dendrite arms. Fractography of 413 alloy fracture surfaces showed that nucleation of microcracks was often associated with silicon particles.
M. Ghalambaz, M. Shahmiri,
Volume 5, Issue 3 (9-2008)
Abstract

Abstract: Cooling slope-casting processing is a relatively new technique to produce semisolid cast feedstock for the thixoforming process. Simple equipment, ease of operation, and low processing costs are the main advantages of this process in comparison with existing processes such as mechanical stirring, electromagnetic stirring, etc. The processing parameters of cooling slope casting are length, angle and the material of the inclined plate and their combinations, which usually affect the micro structural evolutions of the primary solid phase. In order to clarify the effect of the processing parameters on the evolution of the particle size, based on experimental investigation, Artificial Neural Network (ANN) was applied to predict the primary silicon crystals (PSCs) size of semisolid cast ingot via a cooling slope casting process of Al-20%(wt.%) Si alloy. The results demonstrated that the ANN, with 2 hidden layers and topology (4, 3), could predict the primary particle size with a high accuracy of 94%. The sensitivity analysis also revealed that material of the cooling slope had the largest effect on particle size.
S. Kianfar,, S. H. Seyedein, M. R.aboutalebi,
Volume 5, Issue 4 (12-2008)
Abstract

Abstract: The horizontal continuous casting process has received a significant attention for near net shape casting of non ferrous metals and alloys. Numerical Simulation has been widely used for process design and optimization of continuous casting process. In the present study, a 3-dimensional heat flow model was developed to simulate the heat transfer and solidification in a horizontal billet continuous casting system in which the air gap formation and its effect on heat extraction rate from solidifying billet was also considered. In order to test the developed model, it was run to simulate the heat transfer and solidification for an industrial billet caster. The predicted temperature distribution within the mold and billet was compared with those measured on the industrial caster in which a good agreement was obtained. Finally, parametric studies were carried out by validated model to evaluate the effects of different parameters on solidification profile and temperature distribution within the model brass billet. The microstructure of cast billet was analyzed to determine the secondary dendrite arm spacing (SDAS) under different cooling conditions. Based on measured SDAS and predicted solidification rate a correlation between SDAS and cooling rate was proposed for continuously cast brass billet.
I. Ebrahimzadeh, Gh.h. Akbari,
Volume 6, Issue 1 (3-2009)
Abstract

Abstract: Horizontal continuous casting is widely used to produce semi-finished and finished metallic products. Homogeneity in metallurgical characteristics and mechanical properties in such products is of importance. In the present work microstructure and mechanical properties of a horizontal continuous cast pipe have been studied. Microstructural features were investigated by an optical microscope equipped with image analyzer and SEM was used to characterize precipitates. Tensile behavior, impact strength and hardness variations were the mechanical properties which were studied. Results showed that microstructure and mechanical properties had diversities in different parts of the pipe and distinct differences were observed between upper and lower parts of the pipe. A meaningful correlation was found in microstructure and mechanical properties in different parts of the component.
A. H. Shafie Farhood, F. Akhlaghi,
Volume 7, Issue 1 (3-2010)
Abstract

Abstract:

structures in alloys. This method is based on pouring the melt through a small sized nozzle into a mould located at a

certain height under the crucible. This simple method generates globular structures without using equipments such as

impellers, electromagnetic stirrers, ultrasonic probes and cooling slopes. Therefore it is cost effective. In the present

study, the effect of casting size and mould casting modulus on the globular structure evolution in A356 aluminium alloy

specimens prepared by NMS process was investigated. The results showed that regardless of the different casting

modulus and their sizes, all the specimens exhibited globular structures. However, the size and shape factor of the

globules decreased with increased casting modulus and casting size indicating the influential effect of the surface area

of the mould in generating globular structures in this process.

Narrow Melt Stream (NMS) is a relatively new semisolid metal processing technique for producing globular

A. Jafaria, S. H. Seyedeina, M. R. Aboutalebia, D. G. Eskinb, L. Katgermanb,
Volume 7, Issue 3 (8-2010)
Abstract

ABSTRACT Macrosegregation has been received high attention in the solidification modeling studies. In the present work, a numerical model was developed to predict the macrosegregation during the DC Casting of an Al-4.5wt%Cu billet. The mathematical model developed in this study consists of mass, momentum, energy and species conservation equations for a two-phase mixture of liquid and solid in an axisymmetric coordinates. The solution methodology is based on a standard Finite Volume Method. A new scheme called Semi-Implicit Method for Thermodynamically-Linked Equations (SIMTLE) was employed to link energy and species equations with phase diagram of the alloying system. The model was tested by experimental data extracted from an industrial scale DC caster and a relatively good agreement was obtained. It was concluded that a proper macrosegregation model needs two key features: a precise flow description in the two-phase regions and a capable efficient numerical scheme
W. Orlowicz, M. Tupaj, M. Mróz, J. Betlej, F. Ploszaj,
Volume 9, Issue 1 (3-2012)
Abstract

Abstract: This study presents the research results of effect that refining process has on porosity and mechanical properties of high pressure die castings made of AlSi12S alloy. The operation of refining was carried out in a melting furnace with the use of an FDU Mini Degasser. Mechanical properties (UTS, YS, Elongation, Brinell Hardness) were assessed on samples taken from high pressure die castings. The effect of molten metal transfer operation and the time elapsing from completion of the refining process on the alloy mechanical properties was determined.
A. Fardi Ilkhchy, N. Varahraam, P. Davami,
Volume 9, Issue 1 (3-2012)
Abstract

Abstract: During solidification and casting in metallic molds, the heat flow is controlled by the thermal resistance at the casting-mold interface. Thus heat transfer coefficient at the metal- mold interface has a predominant effect on the rate of heat transfer. In some processes such as low pressure and die-casting, the effect of pressure on molten metal will affect the rate of heat transfer at least at initial steps of solidification. In this study interfacial heat transfer coefficient at the interface between A356 alloy casting and metallic mold during the solidification of casting under pressure were obtained using the IHCP (Inverse Heat Conduction Problem) method. Temperature measurements are then conducted with the thermocouples aligned in the casting and the metallic mold. The temperature files were used in a finite-difference heat flow program to estimate the transient heat transfer coefficients. The peak values of heat transfer coefficient obtained for no pressure application of A356 alloy is 2923 and for pressure application is 3345 . Empirical equation, relating the interfacial heat transfer coefficient the applied pressure were also derived and presented.
Mr. Hossein Minouei, Dr. Mohammadhossein Fathi, Dr. Mahmood Meratian, Mr. Hossein Ghazvinizadeh,
Volume 9, Issue 3 (9-2012)
Abstract

ASTM F-75 Cobalt-base alloy castings are widely used for manufacturing orthopedic implants. This alloy needs both homogenization and solutionizing heat treatment after casting, as well as bioactivation of the surface to increase the ability of tissue bonding. In this study, ASTM F-75 Cobalt-base substrate was heat treated at 1220°C for 1 hour in contact with Hydroxyapatite-Bioglass powder in order to solutionize and homogenize the microstructure and promote surface bioactivation. For bioactivity evaluation, heat treated specimens were immersed in Simulated Body Fluid (SBF). Surface of specimens before and after the immersion was analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and X-Ray Diffraction (XRD). Results showed an appropriate microstructure with bioactive layer on the surface of specimens after heat treatment. In vitro result and formation of bone-like apatite layer on specimens indicated that heat treated samples were potentially suitable for bone replacement and tissue regeneration under highly loaded conditions.
Dr Mohammad Reza Allazadeh,
Volume 9, Issue 3 (9-2012)
Abstract

Abstract: A combination of a finite element method (FEM) algorithm with ANSYS codes and post image processing of NDT ultrasonic images along with laboratory cooling experiments and microstructural analysis provide a guideline to determine the optimum cooling rate for any grade of steel in which the highest productivity can be achieved without any degradation of the cast steel products. The suggested FEM algorithm with ANSYS codes is introduced to develop a quasi real models to simulate quenching of as-cast steel with any cooling rate from any initial temperature below steel’s melting point. The algorithm builds a model which is capable to approximate the thermodynamic stresses generated by thermal strain and possible solid-solid phase transformation for as-cast steel with any chemical composition. The model is applicable for any casting geometry (slab, billet and bloom, bar, etc) and adaptable for any method of cooling (unidirectional or multidirectional). Cooling with any cooling agent can be simulated with the algorithm in an ideal case. The phase transformation of the steel in the algorithm can be controlled by Continuous Cooling Transformation (CCT) Diagram obtained from analytical calculation or real time-temperature-transformation experiments for the cast steel. A function for optimizing cooling rate is suggested.
M. Alipour, S. Mirjavadi, M. K. Besharati Givi, H. Razmi, M. Emamy, J. Rassizadehghani,
Volume 9, Issue 4 (12-2012)
Abstract

In this study the effect of Al–5Ti–1B grain refiner on the structural characteristics and wear properties of Al–12Zn–3Mg–2.5Cu alloy was investigated. The optimum amount for Ti containing grain refiners was selected as 2 wt.%. T6 heat treatment, (i.e. heating at 460 °C for 1 h before water quenching to room temperature and then aging at 120 °C for 24 h) was applied for all specimens before wear testing. Dry sliding wear resistant of the alloy was performed under normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu alloy to dry sliding wear.

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