Effect Of Casting Conditions Research Articles

Effect of casting conditions on surface defect and segregation of strips cast by a high-speed twin-roll caster

Effect of casting conditions on surface defect and segregation of strips cast by a high-speed twin-roll caster

Effect of Casting Condition on Ripple Mark and Surface Crack of Roll-Cast Al-Mg Alloy

Effect of casting conditions on ripple mark and surface crack of as-cast Al-4.7%Mg strip was investigated. A vertical type high speed twin roll caster was used. A casting speed was 30 m/min. Casting conditions were tip-shape of a back-dam plate, gap between a roll and the back dam plate and texture on the roll-surface. The texture on the roll-surface was useful to reduce the ripple mark. In bending test conducted to investigate surface crack of as-cast strip, the texture on the roll surface was effective to the reduce the crack. The position of the crack was not coin side with the position of the ripple mark. This result shows that there is no correlation between the ripple mark and the ductility or the strength of as-cast strip. Small roll load was effective to reduce the crack and degree of the ripple mark. Effect of the roll load on the ripple mark was discussed including solidification delay and seepage of Magnesium.

Membranes for the Capture and Screening of Waterborne Plutonium Based on a Novel Pu-Extractive Copolymer Additive.

This contribution describes the fabrication of plutonium-adsorptive membranes by non-solvent induced phase separation. The dope solution comprised poly(vinylidene fluoride) (PVDF) and a Pu-extractive copolymer additive of PVDF-g-poly(ethylene glycol methacrylate phosphate) (EGMP) in dimethylformamide (DMF). The effects of casting conditions on membrane permeability were determined for PVDF membranes prepared with 10 wt% PVDF-g-EGMP. Direct-flow filtration and alpha spectrometry showed that membranes containing the graft copolymer could recover Pu up to 59.9 ± 3.0% from deionized water and 19.3 ± 3.5% from synthetic seawater after filtering 10 mL of 0.5 Bq/mL 238Pu. SEM-EDS analysis indicated that the graft copolymer was distributed evenly throughout the entire depth of the copolymer membranes, likely attributing to the tailing observed in the alpha spectra for 238Pu. Despite the reduction in resolution, the membranes exhibited high Pu uptake at the conditions tested, and new membrane designs that promote copolymer surface migration are expected to improve alpha spectrometry peak energy resolutions. Findings from this study also can be used to guide the development of extractive membranes for chromatographic separation of actinides from contaminated groundwater sources.

Effect of casting conditions on surface cracks at Al-Mg alloy roll cast strips

Effect of casting conditions on surface cracks at Al-Mg alloy roll cast strips

The Effect of Casting Conditions on Shrinkage and Porosity of A356.2 Alloys

The Effect of Casting Conditions on Shrinkage and Porosity of A356.2 Alloys

Electrodes modified with sulphonated poly(aryl ether sulphone): effect of casting conditions on their enhanced electroanalytical performance.

Linear sulphonated poly(arylethersulphone) (SPAES) membranes were tested and compared with Nafion, as electrode modifiers for electroanalytical purposes. Different preparation parameters were evaluated: casting solvent, method of drying and storage, polymer ionic moieties counter-ion. In particular, the casting solvent seems to play a key role in the final modified electrode performances. Four solvents characterized by different boiling point and polarity were tested: dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP). The best electrode, particularly in terms of highest peak currents, was the one prepared using a 1% m/v solution of polymer in NMP, dried at 25°C in a drying oven. Its performances are explained in terms of a favourable membrane organization enabling a thin layer diffusion and/or a preconcentration mechanism.

Modelling-based Innovative Feeding Strategy for Beam Blanks Mould Casting Aimed at As-cast Surface Quality Improvement

Within an investigation focused on effect of casting conditions on steel quality in an industrial beam blanks mould, different nozzle geometries were tested with Computational Fluid Dynamics modelling. The innovative nature of the work consisted in feeding with only one nozzle, whereas two nozzles in the flange-tip zone are commonly used. This configuration has the advantage of a simplified mono-slide gate casting layout, but single nozzle feeding can bring about risks of too high steel velocity in the mould, harmful for shell integrity and meniscus stability. Having in mind the mentioned constraints, different geometry solutions were checked and, to assess the solutions found, suitable indices were defined, related to flow conditions able to prevent slag entrapment at the meniscus, and hot-spotting at walls, harmful for the solid shell integrity. The modelling work gave general indications on undesired flow features and guidelines to improve reference conditions, involving number of holes and holes angle, size and shape. For the caster mould and the operating conditions under concern, a solution was found satisfying the indices, and expected to fulfil the quality requests. It consisted of a nozzle with a 50 mm diameter throat, a 50 mm× 60 mm elliptical lateral port inclined 25° downwards and a 20 mm-diameter bottom hole. A water model check with such a nozzle prototype validated the model supporting the solution identified to be used on plant.

Permeability characterization of hydroxypropylcellulose/ polyacrylonitrile blend membranes

Abstract A series of blend membranes were prepared by immersion precipitation phase inversion method using hydroxypropylcellulose and polyacrylonitrile as raw materials. The effects of casting conditions on membrane’s characterization were studied. The properties of resulting blend membranes were that water flux decreased from 489 L·h-1·m-2 to 312 L·h-1·m-2 ; retention rate increased from 80.1% to 91.8%; and corresponding porosity presented increasing trend but changed little within the range of casting solution concentrations from 10 wt % to 16 wt %. The greater the mass fraction of HPC in casting solution, the greater the water flux of blend membranes. Prolonging the atmosphere exposing time, water flux increased from 268 L·h-1·m-2 about 20s to 372 L·h-1·m-2 about 60 s, then decreased to 340 L·h-1·m-2 about 75s. In addition, retention rate decreased from 91.2% to 81.3%. Porosity tend to decrease but changed a little. With the coagulation bath temperature rising, water flux of blend membranes increased from 306 L·h-1·m-2 about 20 0C to 429 L·h-1·m-2 about 35 0C, and corresponding retention rate decreased from 87.9% to 82.5%, porosity decreased from 80.23% to 68.26%.

Influence of Casting Conditions and Alloy Additions on the Zn22Al2Cu Structure

Zn-Al-Cu alloys are characterized by a number of beneficial properties that include good castability, good tribological properties and low energy input for forming the product. When compared to bronze, Zn-Al-Cu alloys have a lower density. Properties of Zn-Al-Cu can be improved by the partial or total replacement of copper with silicon and rare earth element additions. In the literature there are few studies on the effect of casting conditions and modifying the chemical composition through the introduction of alloy micro-additives on the alloy structure. The aim of this study was to determine the effect of casting conditions and silicon and rare earth element additions on the structure of Zn-22% Al-2%Cu alloy. The subjects examined were the unmodified alloy, the alloy with 1.5% Si and the alloy with 1.5% Si and rare earth elements (mich metal). Samples were cast in sand and graphite molds. The liquidus temperature for each of these examined samples was determined. Structure examinations were carried out in samples taken from the top, center and bottom of the ingot. In order to determine the microstructure of the examined structures metallographic examinations using an optical microscope and a scanning electron microscope with energy dispersive spectroscopy (EDS) capabilities, an X-ray microscope, was performed. Quantitive analysis on specific, characteristic microzones was performed based on the EDS X-ray spectroanalysis results.

Roll Casting of Clad Strip

Roll caster to cast a three layers clad strip was invented and effect of casting conditions on the clad strip was investigated. Two vertical type twin roll casters were set at vertically tandem position to cast three layers clad strip. Roll speed, roll load (separating force), melt temperature and elements of the aluminum alloy were chosen as the experimental conditions to be investigated. The roll load (separating force) and elements of aluminum alloy were important factors to cast sound clad strip. The clad strip could be cast at the speeds up to 40m/min. Interface between the strips were clear and elements of each strip did not diffuse to other strip. The clad strip was not peeled off at the interfaces by continuous bending. Strips were strictly connected at the interfaces.

Effect of casting conditions on aluminium metal quality

A study in a secondary alloy ingot producing plant was targeted to investigate the metal quality change in the holding furnace during secondary remelting of aluminum alloy LM24 (Al–8Si–3Cu–Fe). The investigation was an attempt to understand the effect of: (i) the use of diffusers (porous plugs integrated into the body of the furnace) and (ii) casting techniques involving different degrees of turbulence. Casting density and bifilm index were found to be useful parameters to assess metal quality. It was found that the metal quality was increased significantly, and was maintained high throughout the casting operation when: (i) diffusers were used and (ii) turbulence was reduced to a minimum.

Twin-roll strip casting of AZ61 magnesium alloy and improvement of formability by structure-control rolling

Continuous strip casting and direct rolling method are receiving attention as the integrated producing process to obtain wrought magnesium alloys. In this research, AZ61 strip was cast from molten metal by twin-roll strip caster and rolled by “Structure-Control rolling process”. The effects of casting conditions and rolling parameters on surface aspects and microstructure of the rolled sheet were investigated. The results obtained were as follows: (1) By casting 1.5mm strip, a better surface and finer microstructure were obtained compared to 3mm strip. (2) By using structure-control rolling with R.T. pass, a microstructure of mean grain size of 5μm was obtained. (3) By lowering the starting rolling temperature, mean grain size and duplex grain size degree decreased and hardness increased. In addition, the deformation resistance decreased and the fracture strain increased.

2745 マグネシウム合金板の組織制御圧延による成形性改善(S29-1 アルミニウム合金およびマグネシウム合金の創製と加工技術(1),S29 アルミニウム合金およびマグネシウム合金の創製と加工技術)

Continuous strip casting and direct rolling method are receiving attention as the integrated producing process to obtain wrought Magnesium alloys. In this research, AZ61 strip was cast from molten metal by twin-roll strip caster and it was rolled by "Structure-Control rolling process". The effects of casting conditions and rolling parameters on surface aspect and microstructure of the rolled sheet were investigated. Obtained results are as follows: (1) By using structure-control rolling with R.T. pass, microstructure of the mean grain size of 5μm was obtained. (2) By lowering starting rolling temperature, mean grain size and duplex grain size degree decreased and hardness increased. In addition, the deformation resistance decreased and the fracture strain increased.

Effect of casting conditions on dendrite-amorphous/nanocrystalline Zr–Nb–Cu–Ni–Al in situ composites

High-strength in situ composites with enhanced ductility were prepared by various casting methods from Zr–Nb–Cu–Ni–Al alloys related to bulk metallic glass compositions. The composites exhibit a bimodal size distribution consisting of bcc β-Zr dendrites stabilized by the addition of Nb and a nanocrystalline/amorphous matrix. The dendrite and matrix crystallite size and the morphology depend sensitively on casting conditions. The cooling rates estimated from the secondary dendrite arm spacing of the Zr 73.5Nb 9Cu 7Ni 1Al 9.5 alloy vary between ϵ≈2.6×10 3 K/s to 4.0×10 1 K/s. The effect of processing parameters on the mechanical properties is less significant for the Zr 66.4Nb 6.4Cu 10.5Ni 8.7Al 8.0 alloy while highly pronounced for the Zr 73.5Nb 9Cu 7Ni 1Al 9.5 alloy, where optimum properties like fracture stress of 1754 MPa and 17.5% strain to failure were achieved for cast rods 10 mm in diameter. The deformation of the composite proceeds partly through dislocation movement in dendrites and a shear banding mechanism in the nanostructured matrix.

Factors influencing activated carbon-polymeric composite membrane structure and performance

Hybrid carbon-polymeric composite membranes were synthesized by an immersion-precipitation method using polysulfone as polymer precusor and activated carbon dissolved in dimethyl formamide as casting solution. Surface analysis by scanning electron microscopy (SEM) allowed studying the morphology of membranes as a function of synthesis conditions (carbon loading and particle size). Membrane porosity distribution and mean pore size were obtained numerically using IFME ® program. Effect of casting conditions over carbon was also investigated by SEM. Hybrid membrane performances were characterized in terms of water and oligomeric flux in a continuous operation mode. Selective rejection of dextranes of high molecular weight was obtained. Results showed that permeability for composite membranes is influenced basically by loading and activated carbon particle size, giving rise to materials with a better performance than non-hybrid ones for this application.

Effect of casting conditions on microstructure and mechanical properties of high-strength Zr 73.5Nb 9Cu 7Ni 1Al 9.5 in situ composites

A novel Zr 73.5Nb 9Cu 7Ni 1Al 9.5 composite consisting of dendrites in a nanocrystalline/amorphous matrix was developed. Room temperature compression tests reveal an unusual combination of high strength (1740 MPa) and ductility (4.0–17.5% strain to failure), which sensitively depends on bimodal size distribution of the phases and the casting technique employed.

The effect of casting conditions on the formation of longitudinal surface crack in the beam blank caster

To understand the effects of casting conditions on the formation of longitudinal surface crack, the crack morphology of over 2000 charges at scarfed beam blanks were investigated. The results whow that the most sensitive crack susceptibility range of carbon contents lie in the 0.12–0.13 wt.% range. This was due to the effect of shell irregularity between mold surface and solidified shell withdrawn by δ-γ transformation and the embrittlement phenomena by liquid film of soluble elements such as phosphorous and sulfur at the dendrite interface. It was found that the increase of crack formation is attributed to the increase of phosphorous and sulfur contents segregated at the dendrite interface. The increase of crack formation with increasing Phosphorous and Sulfur contents is due to the enlargement of the ΔT range, which is defined as the temperature difference between LIT (liquid impenetrable temperature) and ZDT (zero ductility temperature). The effect of casting speed on crack formation shows a linear relationship. As casting speed is increased, the solidified shell had little time to grow and the width of shell became smaller. As, the heat flux from the thinner shell increased, the thermal strain was increased, increasing crack formation.

Structure and properties of the mesophase of syndiotactic polystyrene. I. Effect of casting conditions on the preparation of the mesophase

AbstractA syndiotactic polystyrene–toluene solution was cast under two different casting conditions to obtain the δ form. A systematic study of its conformational transition, thermal behavior, and structural transformation as functions of the annealing temperature and time was performed. Spectroscopic studies revealed the content of its helical conformations and its retention up to 190 °C. Thermal analyses showed a significant difference in the transformation from the γ form to the α form. The retention of the intermediate emptied clathrate form (mesophase) of the conformational order for a longer duration (from 120 to 180 °C) in a syndiotactic polystyrene membrane cast at room temperature was confirmed by X‐ray diffraction analysis. On the basis of the experimental results in this work, the transition mechanism is discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 530–536, 2002; DOI 10.1002/polb.10120

Designing hydrogel coated textile scaffolds for tissue engineering: Effect of casting conditions and degradation behavior studied at microstructure level

Designing hydrogel coated textile scaffolds for tissue engineering: Effect of casting conditions and degradation behavior studied at microstructure level

Acrylonitrile-maleic anhydride copolymer membrane (I): effects of casting conditions

The effects of casting conditions, including casting solution (composition and temperature) and coagulation conditions (pre-evaporation time, temperature and concentration of coagulation bath) on the structure and performance of acrylonitrile–maleic anhydride copolymer membrane have been investigated. The results showed that the water flux decreased gradually while the rejection of bovine serum albumin (BSA) decreased as the concentration of copolymer increased. When the total solid concentration was kept unchanged, the water flux increased with additive polyvinylpyrrolidone (PVP), the rejection did not decrease until the ratio of PVP/copolymer was 60%. When the content of copolymer in the casting solution was kept constant, the water flux decreased rapidly while the rejection increased a little (compared with the case of no additive) as the ratio of PVP/copolymer increased. As to the temperature of casting solution, the water flux had a maximum at 45 °C and the rejection had a maximum and a minimum at 45 and 55 °C, respectively. The water flux had a maximum value when the pre-evaporation time was 40 sec. The rejection of BSA was almost unchanged when the pre-evaporation time was less than 40 sec. and then decreased and reached a minimum value at 60 sec. As the temperature of coagulation bath increased, the water flux reached a maximum at 35 °C while the rejection increased uniformly. With increasing the concentration of DMSO in the coagulation bath, the water flux decreased gradually and got to a minimum at 50 wt% as the concentration of dimethylsulfoxide in the coagulation bath increased, but no apparent effect on the rejection was observed. Copyright © 2000 John Wiley & Sons, Ltd.