Pouring Temperature Research Articles

Influence of pouring temperature on solidification behavior, microstructure and mechanical properties of sand-cast Mg-10Gd-3Y-0.4Zr alloy

Influence of the pouring temperature ranging from 680 to 780 °C on the solidification behavior, the microstructure and mechanical properties of the sand-cast Mg−10Gd−3Y−0.4Zr alloy was investigated. It was found that the nucleation undercooling of the α-Mg phase increased from 2.3 to 6.3 °C. The average α-Mg grain size increased from 44 to 71 μm, but then decreased to 46 μm. The morphology of the eutectic compound transformed from a continuous network into a discontinuous state and then subsequently into an island-like block. The volume fraction of β-Mg24RE5 phase increased and its morphology transformed from particle into rod-like. The increase in pouring temperature increased the solute concentration. YS increased from 138 to 151 MPa, and UTS increased from 186 to 197 MPa. The alloy poured at 750 °C had optimal combining strength and ductility. The fracture surface mode transformed from quasi-cleavage crack into transgranular fracture, all plus the dimple-like fracture, with the micro-porosity and the re-oxidation inclusion as major defects. The average α-Mg grain size played a main role in the YS of sand-cast Mg−10Gd−3Y−0.4Zr alloy, besides other factors, i.e. micro-porosity, morphology of eutectic compounds, re-oxidation inclusion and solute concentration.

Numerical study of solidification of A356 aluminum alloy flowing on an oblique plate with experimental validation

Molten A356 aluminum alloy flowing on an oblique plate is water cooled from underneath. The melt partially solidifies on plate wall with continuous formation of columnar dendrites. These dendrites are continuously sheared off into equiaxed/fragmented grains and carried away with the melt by producing semisolid slurry collected at plate exit. Melt pouring temperature provides required solidification whereas plate inclination enables necessary shear for producing slurry of desired solid fraction. A numerical model concerning transport equations of mass, momentum, energy and species is developed for predicting velocity, temperature, macrosegregation and solid fraction. The model uses FVM with phase change algorithm, VOF and variable viscosity. The model introduces solid phase movement with gravity effect as well. Effects of melt pouring temperature and plate inclination on hydrodynamic and thermo-solutal behaviors are studied subsequently. Slurry solid fractions at plate exit are 27%, 22%, 16%, and 10% for pouring temperatures of 620 °C, 625 °C, 630 °C, and 635 °C, respectively. And, are 27%, 25%, 22%, and 18% for plate inclinations of 30°, 45°, 60°, and 75°, respectively. Melt pouring temperature of 625 °C with plate inclination of 60° generates appropriate quality of slurry and is the optimum. Both numerical and experimental results are in good agreement with each other.

Study of Microstructure Evolution during Semi-Solid Processing of an In-Situ Al Alloy Composite

In the present work, effect of pouring temperature (650°C, 655°C, and 660°C) on semi-solid microstructure evolution of in-situ magnesium silicide (Mg2Si) reinforced aluminum (Al) alloy composite has been studied. The shear force exerted by the cooling slope during gravity driven flow of the melt facilitates the formation of near spherical primary Mg2Si and primary Al grains. Shear driven melt flow along the cooling slope and grain fragmentation have been identified as the responsible mechanisms for refinement of primary Mg2Si and Al grains with improved sphericity. Results show that, while flowing down the cooling slope, morphology of primary Mg2Si and primary Al transformed gradually from coarse dendritic to mixture of near spherical particles, rosettes, and degenerated dendrites. In terms of minimum grain size and maximum sphericity, 650°C has been identified as the ideal pouring temperature for the cooling slope semi-solid processing of present Al alloy composite. Formation of spheroidal grains with homogeneous distribution of reinforcing phase (Mg2Si) improves the isotropic property of the said composite, which is desirable in most of the engineering applications.

Grain refinement of Al-Mg-Sc alloy by ultrasonic treatment

In foundry practice, ultrasonic treatment has been used as an efficient technique to achieve grain refinement in aluminium and magnesium alloys. This article shows the strong effect of pouring temperature and ultrasonic treatment at various temperatures on the grain refinement of Al-1 wt% Mg-0.3 wt% Sc alloy. Without ultrasonic treatment, a fine grain structure was obtained at the pouring temperature of 700 °C. The average grain size sharply decreases from 487 ± 20 to 103 ± 2 μm when the pouring temperature decreases from 800 to 700 °C. Ultrasonic vibration proved to be a potential grain refinement technique with a wide range of pouring temperature. A microstructure with very fine and homogeneous grains was obtained by applying ultrasonic treatment to the melt at the temperature range between 700 and 740 °C, before pouring. Cavitation-enhanced heterogeneous nucleation is the mechanism proposed to explain grain refinement by ultrasound in this alloy. Moreover, ultrasonic treatment of the melt was found to lead to cast samples with hardness values similar to those obtained in samples submitted to precipitation hardening, suggesting that ultrasonic treatment can avoid carrying out heat treatment of cast parts.

Modelling for surface roughness of non-ferrous alloy castings using response surface methodology

Surface roughness (SR), in case of a casted functional component is always regarded as a good predictor of the performance as it affects the magnitude of friction forces at mating surfaces. The objective of this paper is to develop a mathematical model in order to investigate the influence of casting process parameters like: shell wall thickness (SWT), pouring temperature (PT) and weight density (WD) on the quality of surface produced in shell casting. After identification of the benchmark, three dimensional printer (3DP) was used to make shell moulds for casting of non-ferrous alloy (NFA). The experiments were conducted using NFA materials like; aluminium, zinc, lead, copper, brass and bronze. SR was measured with Mitutoyo SJ-201 surface profile tester and the results obtained were used for developing a regression model using response surface methodology (RSM). A second order mathematical model, in terms of casting parameters, has been developed for the prediction of roughness parameter. Further, the model developed was validated by analysis of variance (ANOVA) which indicated the significance of model. The statistical analysis showed that SWT and PT were the most significant parameters for SR.

Influence of Fluidity of Al-Cu Alloy with Fly Ash Reinforcement by Single Spiral Fluidity Test

The fluidity is one of the most important properties to be considered for the cast alloys. The quality of the casting is influenced by the fluidity of the liquid metals especially under gravity conditions. The aim of the present investigation is to study the influence of pouring temperature and average grain size with addition fly ash on the fluidity of Al-Cu alloys using a single spiral test. The experiment has been conducted for temperatures at 800°C, 780°C and 740°C. It was been found with metallographic observations that the fluidity was been increased with increasing the grain size and Al2Cu and carbon rich phase tending to increase the fluidity at minimum pouring temperature for the aforesaid alloy. And it also been concluded that at minimum pouring temperatures, the fluidity was enhanced.

Modeling and Analysis for Hardness and Structure of Nonferrous Alloy castings produced using Zcast Metal casting Process through Response Surface Methodology

The purpose of this investigation is to develop a mathematical model for predicting the influence of casting parameters on hardness of non ferrous alloy (NFA) castings produces using Zcast process by employing response surface methodology (RSM). An association has been proposed between hardness of castings and shell wall thickness (SWT), weight density (WD) and pouring temperature (PT) of the shell mould fabricated using three dimensional printer (3DP). The experiments were conducted using NFA materials like; aluminium, zinc, lead, copper, brass and bronze. An effective procedure of RSM has been utilized for the optimal values of casting parameters. Mechanical Micro-Vickers hardness was measured in which the indent is produced by applying a known load to the specimen and then measuring the size of the appropriate diagonals optically. Based on experimental data the investigation has led to conclusion as Quadratic model have been established for predicting the response in the form of hardness of castings.Further, the model developed was validated by analysis of variance (ANOVA) which indicated the significance of model. The Model F-value of 2477.66 implies that the model is significant. There is only a 0.01% chance that a Model F-Value could occur due to noise. Values of "Prob > F" less than 0.05 indicate model terms are significant. The statistical analysis of second order quadratic equation results showed that the most significant parameters, favoring the hardness are B, C and A2. The superiority of the quadratic mathematical models were developed in confidence intervals of 99.75% with prediction error sum of squares of 3.6%for the prediction of the harness. Microstructure analysis was also performed for justification of hardness data.

402 消失模型鋳造法による薄肉アルミニウム合金鋳物の湯流れに及ぼす模型発泡倍率の影響(OS4-(1),OS4 オーガナイズドセッション≪材料・組織と加工≫)

The effects of the pattern expansion ratio and the pouring temperature on the mold filling for a thin wall aluminum alloy casting in the expendable pattern casting (EPC) process was investigated experimentally. An aluminum alloy plate was cast by the EPC process, and the fluid lengths of the molten metal were measured for two expendable polystyrene (EPS) pattern with different expansion ratios. When the thin EPS pattern is used, the fluid length of the melt is shorter, because of the increase of the heat release area per unit volume of the melt. When the coat permeability is less than approximately 2, the fluid length of the melt increases with increasing of the coat permeability. When the coat permeability is greater than approximately 2, because the melt velocity hardly increases even if the coat permeability increases, the increase of the fluid length of the melt is small. The use of the EPS pattern with a high expansion ratio led to the long fluid length of the molten metal. The reason for this may be the decrease of the temperature drop at the melt surface due to the increase of the melt velocity.

Porosity of Solid and Cored Turbine Blades of Aircraft Engines

Paper presents results of quantitative evaluation of porosity conducted on big, thin walled airfoil turbine blades made from Inconel 713C alloy. To decrease mass, blades are design and manufacture like thin walled cored castings. Manufacturing of big thin walled casting airfoil blades is extremely difficult. During exploitation casting work undergo cycle fatigue. In that cause casting should be free of casting defects, including porosity. Conducted research focused on Inconel 713C superalloy pouring temperature effect on porosity level of cored casted turbine blade. Results were compared to porosity of solid casted turbine blade. It was found that porosity of cored blades is lower than solid blade porosity. In cored blades higher porosity is located on airfoil convex side. Airfoil concave side has lower porosity.

Effects of Compound Treatment of Pulsed Magnetic Field and Mechanical Vibration on Solidified Structure of Mg<sub>97</sub>Y<sub>2</sub>Cu<sub>1</sub> Alloy

The influences of different pulse voltage, pulse frequency, pouring temperature and mold temperature on solidified structure of Mg97Y2Cu1 alloy reinforced by long-period ordered structure with compound treatment of pulsed magnetic field and mechanical vibration were studied. The results show that grains of the alloy can be refined greatly with compound treatment. Primary phase degrades from developed dendrites into rosette-shaped crystal. Distribution of second phase is more uniform and continuous, and its volume fraction increases. When the pulse voltage is at 0-280V or the pulse frequency is at 1-10Hz, grain size of the alloy decreases dramatically as pulse voltage or pulse frequency increases. When the pouring temperature is at 660-750°C or the mold temperature is at 20-600 oC, grain size of the alloy with compound treatment decreases grossly with the increase of the pouring temperature or the mold temperature.

Modeling of Dimensional Accuracy in Three Dimensional Printing for Light Alloy Casting

The purpose of this paper is to develop mathematical model to investigate the influence of shell casting parameters. Three input parameters such as shell wall thickness (SWT), Pouring temperature (PT) and weight density (WD) were selected to give output in the form of average outer diameter (AOD) as dimensional accuracy. After identification of component, technological prototypes were produced. In this work three dimensional printing (3DP) has been used as rapid shell casting to make shell mould by using Zcast 501 powder with different shell wall thickness for six different light alloy materials. Measurements on a coordinate-measuring machine helped in calculating the dimensional tolerances of the castings produced. For obtaining tight casting tolerances the dimensional accuracy of component is the most important element. The thickness, curing time and orientation of the shell molds, play an important role in providing a high quality of the cast part in time. The dimensional accuracy was found to be more in the case of maximum layer thickness and horizontal position of the component. The investigation has led to conclusions as the Quadratic models were developed for the response. The F - value is 23.93, which implies that the model as well as lack of fit is significant. The value of Prob > F is less then the standard value 0.05, which indicates model terms are significant. With the help of Post curing, shell Mold temperature was not found to affect the dimensional accuracy of the castings, significantly. It was observed that high pouring temperatures also produced castings with better dimensional accuracy. This study will provide main effect of the inputs on average outer diameter as dimensional accuracy in three dimensional printing of light alloys castings. Statistically in this case B, C, A2, B2, C2, AB, BC is the model terms which contributes significantly to the model developed for dimensional accuracy.

Microstructure and dendrite morphology of Sip/ZA27 composite

The effects of pouring temperature, Si content and P modification on the microstructures and dendrite morphologies of Sip/ZA27 in situ composites have been investigated. Especially, the dendrite morphologies have been visually shown through observation of shrinkage porosity microstructure. The results indicate that the primary α-Al grains change from equiaxed dendrites to parallel distributed columnar-like dendrites as the pouring temperature rises from 575 to 800°C. The change tendency in dendrite morphology with increasing Si content is opposite to that with rising pouring temperature. However, these parallel distributed dendrites with highly anisotropic morphology are not feathery grains. The P modification promotes the formation of feathery grains, and this kind of grains can form when the P modified 4·76 wt-% Sip/ZA27 composite is poured at 750°C. There are four lines of secondary dendrite arms around one primary trunk of a feathery grain. Two of them are located in the twin plane (111), and they are easier to grow up than the other two. Therefore, the feathery grains are always in a laminar structure that is overlapped by two-dimensional structured laminar dendrites. The formation process and three-dimensional structure of the feathery grains have also been discussed.

Influence of melt pouring temperature and plate inclination on solidification and microstructure of A356 aluminum alloy produced using oblique plate

The preparation of semisolid slurry of A356 aluminum alloy using an oblique plate was investigated. A356 alloy melt undergoes partial solidification when it flows down on an oblique plate cooled from underneath by counter flowing water. It results in continuous formation of columnar dendrites on plate wall. Due to forced convection, these dendrites are sheared off into equiaxed/fragmented grains and then washed away continuously to produce semisolid slurry at plate exit. Melt pouring temperature provides required condition of solidification whereas plate inclination enables necessary shear for producing semisolid slurry of desired quality. Slurry obtained was solidified in metal mould to produce semisolid-cast billets of desired microstructure. Furthermore, semisolid-cast billets were heat treated to improve surface quality. Microstructures of both semisolid-cast and heat-treated billets were analyzed. Effects of melt pouring temperature and plate inclination on solidification and microstructure of billets produced using oblique plate were described. The investigations involved four different melt pouring temperatures (620, 625, 630 and 635 °C) associated with four different plate inclinations (30°, 45°, 60° and 75°). Melt pouring temperature of 625 °C with plate inclination of 60° shows fine and globular microstructures and it is the optimum.

Correlation vs. Causation: The Effects of Ultrasonic Melt Treatment on Cast Metal Grain Size

Interest in ultrasonic treatment of liquid metal has waxed and waned for nearly 80 years. A review of several experiments representative of ultrasonic cavitation treatment of Al and Mg alloys shows that the theoretical mechanisms thought to be responsible for grain refinement are (1) cavitation-induced increase in melting temperature predicted by the Clausius-Clapeyron equation and (2) cavitation-induced wetting of otherwise unwetted insoluble particles. Neither of these theoretical mechanisms can be directly confirmed by experiment, and though they remain speculative, the available literature generally assumes that one or the other or both mechanisms are active. However, grain size is known to depend on temperature of the liquid, temperature of the mold, and cooling rate of the entire system. From the reviewed experiments, it is difficult to isolate temperature and cooling rate effects on grain size from the theoretical effects. Ultrasonic treatments of Al-A356 were carried out to isolate such effects, and though it was found that ultrasound produced significant grain refinement, the treatments also significantly chilled the liquid and thereby reduced the pouring temperature. The grain sizes attained closely correlated with pouring temperature suggesting that ultrasonic grain refinement is predominantly a result of heat removal by the horn and ultrasonic stirring.

Influence of Different Cross Sections on Fluidity Characteristics of A356

Fluidity of cast metals are typically measured by the length of metal that is stopped by the solidification where the filling is carried out at a constant cross sectional mold cavity. In this work, a sand mold geometry with different section thicknesses were used to measure the fluidity characteristics of A356 alloy at various casting temperatures (700, 725, 750 °C) with and without modifications. It was found that Ti modification had no significant effect on fluidity. On the other hand, the highest fluidity was achieved by Sr modification even at low pouring temperatures. The results were compared with simulation software (SolidCast), and critical fraction of liquid (CFL) was determined.

Segregation behavior of ADC12 alloy differential support formed by near-liquidus squeeze casting

Near liquidus squeeze casting, a new technology of squeeze casting, can form globular structure without preparation of semi-solid slurries or billets at near liquidus pouring temperature. In this paper, the segregation behavior at different positions and across the selected section of ADC12 alloy differential support formed by near-liquidus squeeze casting are investigated. The results show that at different positions, different cooling rates result in different segregation characteristics, and different element contents lead to different microstructure and Vickers hardness. Overall, the thin walled position has the best microstructure compared with other positions of differential support. Segregations occur mostly at edge and center regions on the selected section. The 3mm width edge region has gradual change of element contents, microstructure and Vickers hardness. The center region is the maximum segregation region across the section. Compared with the region around, it has bigger difference of element contents, different microstructure and Vickers hardness. As the cooling rate of center region increases, the area of center segregation decreases and eventually disappears. Design for thinner wall thickness and appropriate mold cooling system could eliminate the center segregation.

Influence of Pouring Temperature on the Solidification Characteristics of A357 Aluminium Alloy

With the decline of pouring temperature in the range of 750°C~675°C, solidification curve was shifted to left primitively, and then gradually turned to right. Temperature of concretion nucleation and binary eutectic reaction was increased after a reduction, whereas the time was presented dynamically, both the minimum value which were obtained at 715 °Care 23.48s and 89.24s respectively. Growth time of crystal nucleation was extended after a slight decrease, the lowest point which was appeared at 715°C is 607.25s, time of binary eutectic reaction was varied as the cubic polynomial, the minimum value that emerged at 715°C is 228.39s. Solidification curve was changed as the exponential function, cooling rates ascended initially and then dropped andante, the peak point that achieved at 715°C is 5.93°C/min. The test results of microstructure shows that the content of primary and eutectic silicon with the plate-like and needle morphology, was increased primarily and then decreased with the decline of pouring temperature, however, the changing trend of grain size was shown as opposite, the minimum value which was obtained at 715°C is 534μm. It was also found from the results of grain size that with lower pouring and binary eutectic temperature, along with higher cooling rate and nucleation temperature, grain size was refined properly.

Investigation of the controlled atmosphere of semisolid metal processing of A356 aluminium alloy

The cooling slope (CS) method is one of the semi-solid methods in which the molten alloy with a suitable amount of superheat is poured on a cooling slope to achieve a fine and non-dendritic structure. After pouring, the melt, which becomes semisolid at the end of the plate, is subsequently poured into a cylindrical steel mold with different mold temperatures. Also, the process has been done in different cooling slopes and different cooling lengths. This work, at first discusses the effect of these parameters on the final microstructure of A356 aluminum alloy and then the effect of the controlled atmosphere is discussed. Also, in this research, the advantages of using the controlled atmosphere system are discussed by tests such as XRD, SEM and ultrasonic test. Results indicate that the pouring temperature, mold temperature, cooling slope and cooling length have significant effects on the size and morphology of α-Al phase. Also, the controlled atmosphere could optimize the process as well and increase the mechanical properties of alloy.

Numerical Simulation of Semi-Solid Die Casting Technology of Bearing Cage

Semi-solid die casting instead of conventional casting was used to produce bearing cage, Model of semi-solid die-casting was established based on power cut-off (PLCO) model and ProCast 2008 to simulate the effects of processing parameters on deformation process, through orthogonal experiment and analysis of defects, the reasonable technological parameters for using A356 aluminum alloy to finish semi-solid die casting of bearing cage were obtained: the pouring temperature was580°C, the preheating temperature of the mould was 200°C, and the injection velocity was 20 mm/s.

Effects of Cr and Cooling Rate on Segregation and Refinement of Primary Si in Al-20 WT %Si Alloy

The effect of Cr on segregation and refinement of primary Si in Al-20 wt %Si alloy under a different cooling rate was investigated with a wedge-shaped mould. In addition, the effects of P and a combination of P and Cr on Al-20 wt %Si were also studied. Thermal analysis techniques were used to calculate the cooling rate in the solidification range. The microstructures were examined by optical microscope and scanning electron microscope. The results showed that the segregation of primary Si exists in the castings. The optimal pouring temperature was 850°C (1562°F) with a range of 800–900°C (1472–1652°F). Segregation of primary Si could be inhibited with the addition of refiners and increasing cooling rate. The CrSi2 particles adhered to primary Si particles further reduced the segregation. The primary Si particles were well refined by Cr, P or a combination of P and Cr for CrSi2 and AlP served as heterogeneous nucleus for primary Si, but P had a better refinement effect than Cr. A combination of P and Cr into the melt improved the P refinement effect and substantially inhibited the segregation of primary Si.