Centrifugal Casting Research Articles

Approach to Estimate the Phase Formation and the Mechanical Properties of Alloys Processed by Laser Powder Bed Fusion via Casting.

A high-performance tool steel with the nominal composition Fe85Cr4Mo8V2C1 (wt%) was processed by three different manufacturing techniques with rising cooling rates: conventional gravity casting, centrifugal casting and an additive manufacturing process, using laser powder bed fusion (LPBF). The resulting material of all processing routes reveals a microstructure, which is composed of martensite, austenite and carbides. However, comparing the size, the morphology and the weight fraction of the present phases, a significant difference of the gravity cast samples is evident, whereas the centrifugal cast material and the LPBF samples show certain commonalities leading finally to similar mechanical properties. This provides the opportunity to roughly estimate the mechanical properties of the material fabricated by LPBF. The major benefit arises from the required small material quantity and the low resources for the preparation of samples by centrifugal casting in comparison to the additive manufacturing process. Concluding, the present findings demonstrate the high attractiveness of centrifugal casting for the effective material screening and hence development of novel alloys adapted to LPBF-processing.

Utilization of machining chips waste for production of functionally gradient magnesium matrix composites

In this study, lightweight functionally gradient materials (FGMs) with graded behavior were produced utilizing AZ91D magnesium chips reinforced with boron carbide particles through a centrifugal casting method. Innovatively, the influence of reuse magnesium chips generated during machining processes on the gradient formation and mechanical characteristics of graded composites was investigated. Also, the effect of strengthening mechanisms on graded composites was deeply explored. The results showed a considerable improvement in particle distribution inside the matrix, owing mostly to a pre-mixing technique for chips and particles before melting during the preparation steps. The study also found that due to the higher particle concentration, the mechanical characteristics of the graded composite were much better in the outer region than in the transition and inner regions. As a result of the microstructure gradient, the tensile strength of the graded composites increased from 164 MPa to 210 MPa (at the outer zone), the compressive strength increased from 312 MPa to 339 MPa (at the outer zone), and the hardness increased from 63.7 HV to 110.8 HV (at the outer zone). Additionally, the findings reveal that the theoretical values are in good agreement with the experimental values of the concentration of B4C particles within the AZ91D matrix alloy. The above research work can provide a new perspective on using magnesium chips as a matrix material reinforced with ceramic particles for fabricating gradient composites, hence promoting potential applications.

Experimental and numerical studies on the influence of centrifugal casting parameters on the solidification structure of Al-Cu alloy

A horizontal centrifugal casting experiment was designed to determine the change in the solidification structure of Al-Cu alloy casting and the underlying variation in temperature, then obtained interface heat transfer coefficient by inverse calculation. The continuous simulation of metal melt filling from the gate to copper mold cavity is realized. The influence of centrifugal speed, pouring temperature, and mold preheating temperature on the solidified structure was analyzed. Simulation results showed that increasing the centrifugal speed mainly enhance the solidification rate of the molten metal and then refined the solidified structure of the Al-Cu alloy. Increasing the pouring temperature and mold preheating temperatures coarsen the grain size of the casting, but the range of change is small.

A literature review on Al-Si alloy matrix based in situ Al-Mg2Si FG-composites: Synthesis, microstructure features, and mechanical characteristics

The current study examined a comprehensive review of the literature on functionally graded composites, particularly Al-Mg2Si in situ metal matrix composites. Functionally graded Al-Si-Mg2Si in situ metal matrix composites are potential materials for meeting a variety of property demands in various components of automotive engines. The in situ formed intermetallic compound Mg2Si in Al-Si matrix exhibits a high melting temperature, low density, high hardness, a low thermal expansion coefficient, and a reasonably high elastic modulus. Due to all of aforementioned characteristics, Mg2Si is an attractive form of reinforcement that can be created in situ using a simple melt reaction approach. However, the coarse size of primary Mg2Si reinforcement in cast composites is a demerit which reduces the strength and ductility of the ultimate composite. Hence several researches have been attempted to refine the primary Mg2Si particles as well as to change the morphology of the eutectic structure. Apart from the monolithic in situ cast composites, attempts have been made to develop functionally graded (FG) composites in which the volume% of segregation of reinforcements are intentionally varied from one surface to another. These types of FG composites are economically developed by centrifugal casting technique in which Mg2Si reinforcements are segregated to inner the surface due to lower relative density with respect to the molten Al matrix. This type of graded microstructure results in higher strength, hardness and wears resistance at the inner surface of the tubular products. The as-cast microstructure and properties are significantly improved by solution treatment and aging. In the last, some of the most recent manufacturing techniques for FG-composites are addressed, along with their benefits, drawbacks, and applications. In general, all cutting-edge and detailed surveys of the present state of knowledge are included in this article.

Infiltration of aluminum in 3D‐printed metallic inserts

AbstractAluminum structural composites through the infiltration process can be performed by vacuum, centrifugal, or squeeze casting, involving the infiltration of molten Al into fibers, particles, foams, or even porous preforms. This methodology creates hybrid structures of two distinct metal alloys that can be used to locally strengthen components or even to improve the properties of bulk materials, such as ultimate tensile strength and thermal conductivity. New approaches involve the infiltration of liquid Al into a three‐dimensional (3D)‐printed structure of the more rigid metal, such as steel, that the Al matrix. In the current study, stainless steel and copper inserts were produced by fused filament fabrication techniques with various geometries. Moreover, some 3D inserts were electrochemically coated with pure copper to enhance the wettability of the steel insert by Al. Then, the infiltration of these inserts was evaluated by gravity casting, centrifugal casting, and low‐pressure sand casting (LPSC). Evaluations involved microstructural characterization using optical microscopy and SEM for interface analysis. It is revealed that centrifugal casting is highly reliable to infiltrate the inserts with Al, filling detailed cavities in depth. The copper coating aided in the creation of intimate interfaces. The infiltration at the insert's surfaces, curved‐like topography, is obtained through LPSC though it is affected by the direction in respect of material flow.

Comprehensive analysis of the microstructure, properties and environmental performance of Al2O3-ZrO2 composites obtained via centrifugal slip casting

This research investigates the possibility of preparing Al2O3-ZrO2 composites with different proportions of the Al2O3 and ZrO2 phases by centrifugal slip casting (CSC) method and the effect of the solid phase content (50 vol%, 45 vol%, 40 vol%) on the microstructure and selected properties of the produced materials. The hardness results showed that all the series produced were characterised by high hardness, in the range of 16–19 GPa. The results of the static compression test demonstrated that increasing the solid phase content of the slip in the samples promotes the formation of fewer cracks during the monotonic compression loading of the composites. The LCA results demonstrated that as the content of ZrO2 in the composites increase, their environmental footprint increases.

Effects of different process parameters on microstructure evolution and mechanical properties of 2060 Al–Li alloy during vacuum centrifugal casting

In a vacuum environment, large and near-net-shaped 2060 Al–Li alloy tubes were fabricated by centrifugal casting for the first time, and a heat-flow simulation model was established to study process parameters and the solidification behavior. The microstructure and mechanical properties of the alloy were investigated. It was found that in the forming range, the texture was gradually dominated by fine and homogeneous equiaxed grains (average grain size = ∼64 μm) with the decrease in pouring temperature, and segregation decreased because solute particles moved in orientation for less time under the physical field. The tensile strength of the T8 state reached 541 MPa under the process parameters of pouring temperature = 680 °C and rotational speed = 900 r/min. With the increase in rotational speed, the filling capacity was improved and shrinkage defects were reduced; thus, the alloy exhibited excellent strength. The tensile strength of the T8 state reached 516 MPa under the process parameters of pouring temperature = 760 °C and rotational speed = 1000 r/min.

Ellipsoidal equiaxial grain of 7055 aluminium alloy in vacuum centrifugal casting

The 7055 aluminium alloy cast tube was prepared by vacuum centrifugal casting technology. The radial and axial microstructure of the alloy was observed by optical microscope and electron probe. The results showed that the as-cast microstructure is uniform and fine equiaxed, and intermetallic compounds are distributed at grain boundaries. In addition, the circumferential grain size and the number of intermetallic compounds were larger than that in the axial direction. The grains are ellipsoidal and equiaxed. This is the result of directional heat conduction, solid solubility migration and redistribution of solute during the solidification process of centrifugal casting. After homogenisation, the grains tend to be spherical equiaxed crystals, which is the result of different degrees of recrystallisation in the circumferential and axial directions.

Numerical Simulation of Density Segregation of Al Alloy During Centrifugal Casting

The centrifugal casting process of 6082 Al alloy was simulated by ANSYS Fluent software. The effect of rotation speed on the flow field and the degree of density segregation of Mg2Si particles was analysed. The linear velocity of the molten metal increased as the rotational speed increased. The Discrete Phase Model was used to track the movement of the particles. In centrifugal casting, the Mg2Si with low density is segregated toward the inner wall of the casting. As the rotation speed increased, the thickness of the enriched layer decreased, but the mass fraction in enriched layer increased, and the degree of segregation intensified.

Study on the preparation technology of centrifugal Al-18Si-X composite reinforced with in situ particles

Al-18Si-X (X=Mg, Ti, Ni) composite tubular castings were prepared by centrifugal casting. The microstructure of cylindrical casting of Al-18Si-X composite was observed along the radial direction, and the segregation behavior and distribution characteristics of primary particles formed in different alloys under the action of centrifugal field were studied. The results show that the in situ particles in Al-18Si-7Mg, Al-18Si-7Ti, and Al-18Si-7Ni tubular castings have different segregation behaviors under the action of centrifugal field, which results in the formation of particle reinforcing layers in different regions of the castings. It is found that the volume fraction, size and particle morphology of primary particles in particle reinforcement layer of different castings are different.

Understanding centrifugal casting in the manufacture of functionally graded materials

Centrifugal casting is a shaping technique intended for ceramic tubular structure manufacture, where the particle size and density are exploited to produce asymmetrical membranes and functionally graded materials. However, some well-established insights about particle segregation are debatable and remain unclear. For instance, small particles do not necessarily stay in the inner region, and the bigger particles do not accumulate in the outer. Herein several manufacturing parameters were studied through Taguchi’s robust design, using discrete element method-based simulations to generate the data. Alumina powder was used as model material and water as the liquid phase, to assess the green cast formation time, the cast thickness, the roundness, the changes in relative density, and particle size distribution along the cast’s cross-section. The mean particle diameter and the rotation speed are the most influential parameters for the casting time. The volume fraction of solids on the precursor slurry is decisive regarding the cast structural properties, and particle segregation is negligible, except for size differences above one order of magnitude. When a fraction of denser nickel powder was added, density segregation was also observed, but the size differences can overshadow its effect. In addition, alumina and nickel particles were cast in a lab-scale centrifuge and experimentally validated the segregation of particles. The centrifugal casting method was successfully applied for producing the Al2O3-Ni composites with a gradient distribution of the Ni phase.

The anisotropy of bonded ferrite magnets obtained by centrifugal casting in magnetic field

• The orientation of bonded magnets in an external magnetic field depends on the powder particle size. • For powders composed of multidomain particles, the orientation occurs in the circumferential direction. • The orientation of the powder occurs in a way that leads to a minimization of the energy. Bonded magnets were produced by centrifugal casting of a powder mixture comprising a magnetically hard material (strontium ferrite) and a chemically hard polymer (epoxy resin) in an external, constant magnetic field perpendicular to the axis of rotation. The tests were carried out for commercial strontium ferrite powder, with micrometre-sized particles. At 5% and 10% powder content by volume, the magnets exhibited a gradient structure, i.e. the proportion of magnetic powder was highest at the surface and decreased towards the sample’s axis. At higher powder content, the viscosity of the slip was high enough to prevent particles to move over significant distances, and no marked change in the proportion of ferrite in the sample volume was observed. Measurements of the magnetic properties in the characteristic directions of the cylindrical sample (radial, axial and circumferential) showed that the powder particles tend to align their easy axis with the axis of the cylinder, i.e. perpendicular to the direction of the magnetic field. These results indicate that the magnetization anisotropy obtained is different from that described in earlier work, where strontium ferrite powder with a particle size above 100 μm was oriented circumferentially (the easy axis was perpendicular to the radius and axis of the cylinder). These differences are due to the different proportion of single and multidomain particles in the two powders and to the different mechanisms of their remagnetization. The results are explained on the basis of the presented model assuming that the single domain particles rotate in such a way that their remagnetization during mould centrifugation is achieved by rotating the magnetization vector in a plane perpendicular to the easy axis, which minimises the energy loss in this process.

Preparation, microstructure, and mechanical behaviour of Ni3Al-based superalloy reinforced with carbide particles

The preparation, microstructure, and mechanical behaviour of Ni3Al-based superalloy have been studied. The superalloy reinforced with carbide particles forming in-situ in the melt was prepared by vacuum induction melting (VIM) followed by centrifugal casting. The as-cast alloy was subjected to heat treatment consisting of solid solution annealing, quenching, and ageing. The microstructure of the heat-treated superalloy consists of blocky MC carbides (6.9 vol%), which are uniformly distributed within the columnar grains containing cuboidal γ′(Ni3Al) precipitates (57.3 vol%) embedded in the γ (Ni-based solid solution) matrix and along γ′ grain boundaries. The equivalent plastic strain distribution in the plastic zone underneath Vickers macroindentation and within the compression specimens deformed to engineering strains ranging from 0.05 to 0.27 is calculated using finite element analysis (FEA). The correlation curve between experimentally measured Vickers microhardness values and calculated equivalent plastic strains has been proposed to quantify the level of local strain hardening state of the studied Ni3Al-based superalloy. The room temperature compressive strain hardening behaviour is evaluated and measured strain hardening exponent and strain hardening rate are discussed.

Fabrication of Highly Transparent Y2O3 Ceramics via Colloidal Processing Using ZrO2-Coated Y2O3 Nanoparticles

An easy approach is described for the preparation of ZrO2-coated Y2O3 nanopowder from a solution of zirconium nitrate with commercial Y2O3 nanopowder. The evolution process of the ZrO2 coating layer upon calcination, such as the phase and microstructure of the particles’ surface, was studied. Calcination of the powder at 700 °C resulted in ZrO2-coated Y2O3 nanopowder. The rheological properties of the suspensions of ZrO2-coated Y2O3 powders were studied. A well-dispersed suspension with a solid loading of 35.0 vol% using ZrO2-coated Y2O3 nanopowder was obtained. The consolidated green body obtained by the centrifugal casting method showed improved homogeneity with a relative density of 50.2%. Transparent ceramic with high transparency and an average grain size of 1.7 µm was obtained by presintering at 1500 °C for 16 h in air, followed by post-HIP at 1550 °C for 2 h under 200 MPa pressure. The in-line transmittance at the wavelength of 1100 nm (1.0 mm thick) reached 81.4%, close to the theoretical transmittance of Y2O3 crystal.

Hot Deformation Behavior Coordination and Processing Maps of 40Cr/Q345B Bimetallic Blank by Centrifugal Casting

The compact cast-rolling compound forming of bimetallic ring is an efficient process for manufacturing large bimetallic rings. The difference in hot deformation behavior of the two metals directly affects the coordinated deformation of bimetals during hot rolling. In this paper, hot compression tests of 40Cr/Q345B bimetallic blank produced by centrifugal casting were carried out at temperatures of 950–1200 °C and strain rates of 0.005–5 s−1. Based on the comparisons of flow stress behavior, activation energy, and activation volume, hot deformation behavior coordination of 40Cr/Q345B bimetallic blank was investigated. Processing maps were established to study the optimum processing windows for 40Cr/Q345B bimetallic blank. Under the same deformation conditions, 40Cr shows lower overall flow stress than Q345B, which facilitate the coordinated deformation of the bimetallic blank during rolling, and the flow stress difference between 40Cr and Q345B decreases with the increase of temperature. It was connected with the increase in the second phase particles pinning effect for higher MnS content in Q345B. The common rate-controlling mechanism for 40Cr and Q345B is the thermal breaking of attractive junctions and movement of jogged screw dislocations. The bimetallic blanks exhibit good deformation coordination in the optimum processing window (1030–1100 °C and 0.5–1 s−1 with a strain of 0.6).

Fabrication of Highly Compacted Green Body Using Multi-Sized Al Powder under a Centrifugal Force

This study investigates the application of centrifugal force for the compaction of metal powder. Previous studies using the centrifugal force for manufacturing the green bodies were focused on fine powders with narrow particle size distribution or binary mixtures. This study explores the particle packing of multi-sized powder. Aluminum alloy powder with a particle size less than 100 µm and polymer binder were admixed and compacted in the centrifugal casting with ranging magnitudes of centripetal acceleration. Three different centrifugal forces were tested: 700, 1800, and 3700 G. The microstructure of the green bodies was then observed on the SEM micrographs. The obtained green bodies had high packing densities ranging from 62 to 69%. The packing density and median particle size increase at the positions further away from the center of rotation of the centrifuge with an increase of centrifugal force. The effect of centrifugal force on the segregation of particles was investigated through the quasi-binary segregation index. The segregation phenomena was not observed at 700 G, but clear particle segregation was found at higher centrifugal forces. The increase of the centrifugal force resulted in higher segregation with finer particles moving to the inner part of the spinning mold, with a significant change in the size of particles located closer to the center of rotation. Overall, the centrifugal process was found to produce highly compacted green bodies while yielding a segregation effect due to wide particle size distribution.

Processing and Microstructure of As-Cast Ti-45Al-2W-xC Alloys.

The metallurgical preparation and microstructure of as-cast Ti-45Al-2W-xC (in at.%) alloys were investigated. Five alloys with carbon content ranging from 0.38 to 1.96 at.% were prepared by vacuum induction melting (VIM) in graphite crucibles, followed by centrifugal casting into graphite moulds. A master 15W-85Al (at.%) alloy with a relatively low melting point and TiC powder were used to facilitate fast dissolution of W during VIM and to achieve the designed content of C in the as-cast alloys, respectively. The increase in the content of C affects the solidification path of the studied alloys. Differential thermal analysis (DTA) and microstructural observations show that the alloys with carbon content up to 0.75 at.% solidify with β primary phase and their dendritic as-cast microstructure consists of the α2(Ti3Al) + γ(TiAl) lamellar regions, retained B2 phase enriched by W and single γ phase formed in the interdendritic region. The increase in the content of C above 0.75 at.% leads to the formation of primary lathe-shaped Ti2AlC carbides, which act as effective heterogeneous nucleation sites of β dendrites during the solidification and grain refinement of the alloys with 1.15 and 1.96 at.% C. The increase in the content of C leads to an increase in Vickers hardness and elastic modulus in the alloys containing 1.96 at.% C.

Enhanced High-Temperature Mechanical Behavior of an in Situ TiAl Matrix Composite Reinforced With Alumina

A Ti-45Al-3Cr-2.5Nb alloy reinforced with in situ formed alumina has been produced by means of centrifugal casting by adding zirconium oxide in the crucible. The dispersion-strengthened alloy has been characterized to verify its microstructure and particle distribution. Mechanical tests carried out over the temperature range 850–950 °C highlighted that in situ formed alumina allows to increase the alloy yield stress by 21% at 850 °C and by 35% at 900 °C. Moreover, the in situ formed oxide particles produced an increase of the Young’s modulus of about 10% at 850 °C and of about 8% at 900 °C. Considering that the tested alloy has a density that is about a half of nickel superalloys, obtaining high specific mechanical properties over the temperature range 850–950 °C can boost its application in the production of turbine blades.Graphical abstract

Rancang Bangun Mesin Cetak Centrifugal Casting untuk Pembuatan Pipa Komposit Geopolimer

In the field of materials engineering, various types of advanced materials have been found. This must also be accompanied by technological advances in the production process. Centrifugal casting is an effective method for casting cylindrical objects such as pipes and pressure vessels. In this research, a centrifugal casting machine is designed and made. The design process follows the steps proposed by Pahl and Beitz, starting from requirements identification, concept design, layout and analysis to the fabrication method. Furthermore, this machine was tested for casting geopolymer composite pipes. From the test results it is stated that this machine works well and can cast pipe samples at various speeds. Furthermore, the sample is cut into a three-point bending test specimen. From the test results obtained bending strength of about 50 MPa (1500 rpm tube rotation) and about 36 MPa (1200 rpm tube rotation). Thus, it is concluded that the higher the tube rotation, the higher the quality of the resulting product.

Microstructure and mechanical properties of Ti–45Al–2W–xC alloys

The microstructure and mechanical properties of five alloys with nominal compositions of Ti–45Al–2W–xC (in at.%), where x is ranging from 0.4 to 2.0 at.%, were studied. The alloys were prepared by vacuum induction melting in graphite crucibles, followed by centrifugal casting into a graphite mould. The as-cast alloys were subjected to hot isostatic pressing and heat treatment consisting of solution annealing, cooling at a constant rate and stabilisation annealing. The microstructure of the heat-treated alloys consists of equiaxed α2(Ti3Al) + γ(TiAl) lamellar grains surrounded by γ grain boundaries with a small amount of β/B2 particles. The α2-α2 interlamellar spacing λ decreases with increasing carbon content until a solubility limit of carbon is achieved. The increase in carbon content above the solubility limit leads to the formation of primary Ti2AlC particles during solidification and an increase in the amount of γ phase at grain boundaries. Vickers microhardness of lamellar grains depends on the carbon content and interlamellar spacing λ. The studied Ti–45Al–2W–0.8C and Ti–45Al–2W–1.2C alloys show improved creep resistance at 800 °C compared to that of the reference carbon-free TiAl–W and carbon-containing TiAl–Nb based alloys with fully lamellar, nearly lamellar, convoluted or pseudo-duplex microstructure.