Pouring Temperature Research Articles

A parametric study on mechanical properties of aluminum–silicon/SiO2 nano-composites by a solid–liquid phase processing

In this article, different aluminum–silicon matrix nano-composites which reinforced by SiO2 nano-particles were developed. The stir casting was used as a solid–liquid phase processing to make such nano-composites. Pouring temperatures and stir times were two parameters which were varied from 700 to 850 °C and 2–4 min, respectively. In addition to microstructural evaluations, the mechanical and tribological properties of different nano-composites were compared to the aluminum alloy without any reinforcement agent. Obtained results showed that the hardness of nano-composites increased significantly when the pouring temperature was 850 °C with respect to the aluminum alloy. The wear resistance was also increased obviously when nano-particles were distributed homogenously in the aluminum matrix. Besides, the ratio of the hardness to the elastic modulus was a compatible parameter to predict the wear rate of most specimens. FESEM images demonstrated that the nano-particles distribution was reasonably uniform. The elastic modulus for all nano-composites increased. The ultimate compressive strength also increased for nano-composites which made at the pouring temperature of 750 °C for both stirring times. The presence of more intermetallic phase especially Al–Ni phase and the micro-cracks were responsible for lowering the toughness of nano-composites which made at higher pouring temperatures.

Cast Iron Components with Intelligence

The paper describes a project with the aim to develop communicating and functional cast iron components in smart systems. The concept is based on sensors integrated into cast iron components; this will influence not only the component but also the casting process. Among the technical challenges is how to choose a sensor solution that cost-efficiently and with minimal environmental impact can be integrated into the component during the casting process, and especially without being damaged during mold filling and the high pouring temperature. Another challenge is how the iron will interact and interfere with sensor signals and whether an insulating intermediate material is needed or not. Integrating the sensors into the casting makes sensors a natural part of the component, which in turn can lead to more resource efficient designs, increased value added for the casting sector, and a general access to different possibilities of digitalization. The integrated sensors can be used for effective control and monitoring of components when in service and give information about for example how the component is used and what conditions it is exposed to. In other words, the component can tell when maintenance is needed or in worst cases, indicate that something is wrong before a failure will happen. Important measurands can e.g. be elongation, shear, temperature and vibration. Different combinations of sensor materials and insulating materials and their interaction with the cast iron have been investigated. It is shown how the interaction at the interface affects the microstructure and consequently the properties of the cast iron. In the case of insulating materials it is e.g. shown how air gaps are formed and in the case of sensor materials it is shown how a diffusion zone is formed and how this zone depends on the sensor material. How this diffusion zone affects the microstructure is discussed.

Investigation on controlling the process parameters for improving the quality of investment cast parts

Investment casting is a highly flexible process which was previously perceived as an expensive process. However, when the process is compared to other optional processes which may require machining or welding, this casting can produce metallic components at highly competitive costs. There are many process variables which affect the process such as die temperature, wax temperature, injection pressure, shell firing temperature and time, cooling rate. In this study, important shell parameters such as preheat temperature, firing temperature and firing time, and melt pouring temperature have been chosen as process variables influencing the quality of the hypoeutectic aluminium–silicon alloy investment casting. The optimal input parametric condition for reduction of linear and volumetric shrinkages and increment of tensile strength of Al–Si 7%–Mg investment casting has been identified as shell preheat temperature of 200 °C, firing temperature of 900 °C, firing time of 7 h and pouring temperature of 600 °C. At this optimal setting, it was found that linear and volumetric shrinkages decreased from 0.65 and 1.89% to 0.381 and 1.546%. The tensile strength of the casting increased from 96 to 121 MPa with regard to the nine experimental runs performed. Microstructural observation revealed that higher shell preheat and pouring temperatures led to augmented porosity, increased secondary dendrite arm spacing (35.53 ± 2.4 μm), larger detrimental iron-rich intermetallics (40.49 ± 25.15 μm) followed by reduced tensile properties of the casting (96 MPa).

Hydrodynamic Modeling and Mathematical Simulation on Flow Field and Inclusion Removal in a Seven-Strand Continuous Casting Tundish with Channel Type Induction Heating

The tundish with heating instrumentation is attracting more and more attention in continuous casting processes for maintaining a pre-determined constant pouring temperature under a given casting speed, which is beneficial for an improved and consistent steel product quality. However, the fluid flow, temperature distribution and the removal behaviors of non-metallic inclusions in it will be much different from that in a conventional tundish, due to the implementation of the heating practice. In the present work, to reduce the non-metallic inclusion amounts in billets of the second and sixth strands in a seven-strand tundish with channel type induction heating, the flow field profiles and temperature profiles of molten steel in this tundish have been investigated using hydrodynamic modeling coupled with mathematical simulation under isothermal and non-isothermal situations, respectively. The results of the isothermal experiment indicate that the prototype tundish has severe “short-circuiting flow” in the second and sixth strands, which might have caused the increased inclusion amounts in the billets of the two strands. The flow field of the tundish can be greatly improved by changing the channel design and adding two high dams at each side of the tundish. Compared with the prototype structure A0, the average residence time of the optimized case C5 is prolonged by 55.49% (from 501 to 779 s); the dead zone volume fraction is reduced by 66.18% (from 45.57% to 15.41%); and the flow of each strand becomes more consistent with lower standard deviation. The non-isothermal experiments show that the fluid presents an obvious rising tendency when it flows out from the heating induction channel. The larger the temperature difference inside and outside the channel is, the more consistent the fluid flow between different strands and the more homogeneous the flow field in the whole tundish. For the prototype tundish structure, when the temperature difference is 5 °C, the dead zone is basically eliminated, and the minimum residence time is prolonged by 789% (from 38 to 338 s), compared with the 0 °C of temperature difference. A mathematic model has been proposed accordingly, which can explain well the hydraulic phenomena. The inclusion removal rates of different cases were compared by mathematical simulation, and their removal mechanism was studied, as well.

Optimization of processing parameters of cooling slope process for semi-solid casting of ADC 12 Al alloy

In the present work, the effect of processing parameters of cooling slope techniques (pouring temperature, slope angle and slope length) of ADC 12 Al alloy on its microstructural evolution has been studied in detail. A series of cooling slope casting experiments were conducted by varying the pouring temperature (580, 585 and 590 °C), slope length (400, 500 and 600 mm) and slope angle (30°, 45° and 60°). The effect of processing parameters on the response factors, viz. degree of sphericity and particle size, has been investigated by applying analysis of variance (ANOVA), interaction graphs obtained using response surface methodology. The obtained results infer that optimum values of the degree of sphericity (0.865) and particle size (49.30) are observed for the following set of processing parameters, namely 585 °C pouring temperature, 500 mm slope length and 45° slope angle. ANOVA results show that the pouring temperature is the most significant input variables that influence degree of sphericity and particle size followed by slope length and slope angle. The values of output variables obtained from confirmation experiment, performed at 95% confidence level, ensure that they are well within the permissible limits.

Manufacture of Nickel Collimator for BNCT: Smelting of Nickel Using Electrical Arc Furnace and Centrifugal Casting Preparation

Collimator is a tube that functions to direct neutrons generated by a nuclear reactor for BNCT (Boron Neutron Capture Therapy Cancer). Appropriate design of the collimator for BNCT application is a tube with an inner diameter of 16 cm, an outer diameter of 19 cm and a length of 13 cm total with 12 pieces with nickel purity above 95%. Manufacturing of the BNCT collimator will be planned using centrifugal casting method and smelting of nickel with electrical arc (EA) furnace. This article reports on the smelting process of nickel, setting the parameters of the electrical arc furnace, and the chemical composition of the nickel. Results of the study show that nickel with purity 98% can be melted perfectly using the EA Furnace with a current of 600-800 A and a pouring temperature of 1600°C. The fluidity of nickel can hold up to 1 minute at a 35°C environment that allows for the centrifugal casting process. The chemical composition of the nickel before being melted is Ni (98.89%), Si (0.79%), S (0.17%), and Fe (0.15%) and after being melted is Ni (97.89%), Si (0.92%), S (0.26%), and Fe (0.90%). The chemical composition of the nickel after smelting in an EA Furnace meets the requirements of BNCT collimator.

Formation of Transverse Surface Cracks During Peritectic Steel Continuous Casting

Various mechanisms of transverse crack formation within the surface of continuously-cast billets in the pouring temperature range are analyzed. It is shown that low mechanical properties of peritectic steels in the high-temperature region are due to the high temperature for completion of the δ→γ transformation (Tγ). The effect is considered individually of grain size on metal mechanical properties. Conditions are analyzed for the formation of coarse grains during continuous casting of peritectic steels. It is shown that in the low-temperature region key effects are stress concentration conditions at grain boundaries and intergranular bond forces. On the basis of this analysis, a series of recommendations is proposed for reducing the probability of forming surface cracks in billets.

Cooling Rate, Hardness and Microstructure of Aluminum Cast Alloys

This experiment investigated the cooling curve behavior, hardness and microstructure of two aluminum alloys produced by casting process. There are Al-1.37Zn-1.19Si and Al-1.66Si-1.35Zn derived from melting and alloying a pure aluminum with ADC12 (Al-Si) ingot. Cooling curve recorded from both those two alloys with pouring temperature at 710 oC and the mold temperature kept constant at 220 oC. The result shows, a freezing range of Al-1.37Zn-1.19Si alloy is 643–348 oC and Al-1.66Si-1.35Zn alloy is 621–401 oC. Then cooling rate obtained for Al-1.37Zn-1.19Si is 55.56 oC/S, and Al-1.66Si-1.35Zn is 30.09 oC/S. TThe higher hardness is 40.42 BHN at Al 1.66 Si-1.35Zn, while the lower value is 34.62 BHN on Al-1,37Zn-1,19Si alloy. The hardness value found higher when cooling rate is shorted. The number of silicon present on microstructure is highest in Al-1.37Zn-1.19Si alloy but the hardness value decreases. This is caused by the distribution of the silicon content in the alloy is irregular. It was found that the solidification rate had an effect on hardness, where the freezing rate obtained a high hardness value.

Cooling Rate, Hardness and Microstructure of Aluminum Cast Alloys

This experiment investigated the cooling curve behavior, hardness and microstructure of two aluminum alloys produced by casting process. There are Al-1.37Zn-1.19Si and Al-1.66Si-1.35Zn derived from melting and alloying a pure aluminum with ADC12 (Al-Si) ingot. Cooling curve recorded from both those two alloys with pouring temperature at 710 oC and the mold temperature kept constant at 220 oC. The result shows, a freezing range of Al-1.37Zn-1.19Si alloy is 643–348 oC and Al-1.66Si-1.35Zn alloy is 621–401 oC. Then cooling rate obtained for Al-1.37Zn-1.19Si is 55.56 oC/S, and Al-1.66Si-1.35Zn is 30.09 oC/S. TThe higher hardness is 40.42 BHN at Al 1.66 Si-1.35Zn, while the lower value is 34.62 BHN on Al-1,37Zn-1,19Si alloy. The hardness value found higher when cooling rate is shorted. The number of silicon present on microstructure is highest in Al-1.37Zn-1.19Si alloy but the hardness value decreases. This is caused by the distribution of the silicon content in the alloy is irregular. It was found that the solidification rate had an effect on hardness, where the freezing rate obtained a high hardness value.

Effects of Pouring Temperature and Electromagnetic Stirring on Porosity and Mechanical Properties of A357 Aluminum Alloy Rheo-Diecasting

Semisolid slurry of A357 aluminum alloy was prepared using a temperature-controllable electromagnetic stirrer and rheo-diecast at different temperatures. The effects of pouring temperature and electromagnetic stirring (EMS) on the porosity in rheo-diecast samples, as well as the relation between porosity and mechanical properties, were investigated. The results show that pouring temperature and EMS had minor influences on rheo-diecast microstructure but marked influence on the porosity. With decreasing slurry pouring temperature, the porosity decreased first and then increased, whereas the maximum pore ratio (ratio of shape factor to diameter of the largest pore) increased first and then decreased. The maximum pore ratio determines the level of tensile strength and elongation, and higher mechanical properties can be obtained with smaller and rounder pores in samples. The mechanical properties of the rheo-diecast samples increased linearly with increasing maximum pore ratio. The maximum pore ratio was 1.43 µm−1, and the minimum porosity level was 0.37% under EMS condition for the rheo-diecast samples obtained at a pouring temperature of 608 °C. With this porosity condition, the maximum tensile strength and elongation were achieved at 274 MPa and 4.9%, respectively. It was also revealed that EMS improves mechanical properties by reduction in porosity and an increase in maximum pore ratio.

Effect of Mould Coatings and Pouring Temperature on the Fluidity of Different Thin Cross-Sections of A206 Alloy by Sand Casting

Thin-wall castings of the A206 alloy can pose a manufacturing problem associated with mould filling which results in fluidity defect. The mould coating generates a smooth surface, and reduces the friction between the melt and mould contact, thus reducing the heat-transfer coefficient, which in turn leads to enhancement of fluidity and mechanical properties. The fluidity of A206 alloy was observed in various cross-sections of the thin channels at three altered pouring temperatures i.e. 700, 750 and 780 °C for uncoated and coated green sand moulds. The Graphite and Soapstone powder coatings were used as sand mould coatings in the present investigation. It was found that the fluidity of aforesaid alloy was significantly increased with the Soapstone powder mould coating at pouring temperature of 750 °C. The characterization of the coating materials was performed by the X-ray diffraction analysis and scanning electron microscope test with EDAX.

Effect of fine alumina in improving refractoriness of ceramic shell moulds used for aeronautical grade Ni-base superalloy castings

This paper discusses an improvement in shell refractoriness and dimensional stability of columnar grained (CG) low pressure turbine blade castings made using Ni base superalloy by directional solidification process (DS). Two ceramic shell systems were adopted, namely shell system I and II. Shell moulds were prepared by using ceramic slurries containing zircon flour as a filler material and colloidal silica as a binder. As compared to shell system II (zircon filler with colloidal silica binder and fine alumina), shell system I (zircon filler with colloidal silica binder) showed lower refractoriness. Shell system II showed an increase in the flexural strength both in the green as well as in fired conditions. Shells made from shell system II showed about 13% higher green strength and 55% higher fired strength as compared to shell system I. Shell system II also exhibited superior self sag resistance up to 1625 °C. Moulds prepared from this shell system yielded aeronautical grade casting with high dimensional accuracy even at a metal pouring temperature of 1550 °C. Moulds from shell system I, on the other hand, underwent sagging even at metal pouring temperature of 1500 °C, leading to dimensionally unacceptable castings. The superior performance of shells prepared from shell system II can be ascribed to the presence of fine alumina in the shell.

Effect of alumina on grain refinement of Al-Si hypereutectic alloys

The size, volume fraction and distribution of primary as well as eutectic silicon affect the mechanical properties of the Al-Si hypereutectic alloys. It is very difficult for the simultaneous refinement and modification of primary and secondary Si particles in hypereutectic Al-Si alloys through traditional processes. This paper explores the role of γ-Al2O3 nanoparticles on Si particles in the course of solidification in hypereutectic Al-Si alloys at particular pouring temperature. The present study involves incorporation of varying contents dispersed γ-Al2O3 nanoparticles into a molten base metal during stir casting and followed by solidification. It has been reported that the synthesized composites having good interfacial bonding (wetting) between the dispersed phase and the liquid matrix was achieved in order to provide improved mechanical properties of the composite. The cast product of hypereutectic Al-16Si alloy with the reinforcement of nanoparticles, illustrated a significant improvement in both wear behaviour and hardness. The dry sliding wear test has been performed on a group of specimens with varying parameters (different loads and sliding velocities) in a pin on disc wear testing machine. Moreover, the wear rate and specific wear rate also affected in different load and different sliding velocities. However in XRD analysis of the samples, the enhancement of wear resistance as well as hardness was due to the formation of brittle phases like SiO2, Al2O3 and Al-rich intermetallic compounds. The hardness value of the materials increases nearly 6% in addition to increase in the density of only 0.8%. As per literature, the large plate eutectic Si particles were modified in to the fine core particles and it acquires enough potential for various applications.

Effect of Sn addition on hot tearing susceptibility of AXJ530 alloy

The effects of different Sn additions (0, 0.5, 1.0, and 2.0 wt%) on hot tearing susceptibility (HTS) of AXJ530 alloy were studied using ‘T-shaped’ hot tearing mold at a pouring temperature of 700 °C and a mold temperature of 200 °C and paraffin permeation method. The dendrite coherency temperature was obtained by means of differential thermal analysis (DTA), and phases evolution, microstructures and morphology of the crack zone of AXJ530-xSn alloys were also investigated by using x-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The experimental results show that the HTS of AXJ530-xSn alloys increases with Sn additions up to 1.0 wt%, and then exhibits a slight decrease with further Sn additions up to 2.0 wt%. The Sn additions into AXJ530 alloy can first form CaMgSn phase with high melting point, reduce amount of α-Mg+(Mg,Al)2Ca eutectic phase, increase the dendrite coherency temperature, decrease the thickness of liquid film and the feeding ability at the end of solidification, resulting in the rise of the HTS. However, the improvement in hot tearing resistance for AXJ530-2.0Sn alloy can be attributed to the grain refinement, lower dendrite coherency temperature and formation of the Mg17Al12 phase with a low melting point to feed more readily at the end of solidification, which improves the state of dendrite and the feeding channel.

Effects of important parameters in the production of Al-A356 alloy by semi-solid forming process

There are many routes to produce feedstock with globular microstructure. Cooling slope methods has been attracted as the result of its simplicity and also produces of the globular shape billets quicker than other methods. In this method molten metal is poured on a tilted slope that is cooled by water circulating underneath. Due to shear stress exerted to the slurry, it is solidified with globular microstructure. By simulation of semi-solid casting with cooling slope the effects of different pouring conditions on the microstructure of A356 aluminum alloy are investigated. The simulations are carried out by a CFD code called FLOW3D. The average diameter and shape factor of primary α-Al particles from experiments and the time duration of slurry presence on the slope, solid fraction of the slurry, strain rate and turbulence from the simulations were investigated. Comparing the results of simulations with experimental results showed that for having the best microstructure with higher sphericity and lowest particle size, the residence time of slurry on the cooling slope must be enough, while the shear stress and turbulence must be as high as possible. Also, combination of the process parameters including pouring temperature, tilt angle and slope length should lead to adequate value of tf, while solid fraction of slurry at the exit of slope is about 30–35%.

Development Of Lead Free Copper Alloy Casting; Mechanical Properties, Castability and Machinability

The regulation for the lead discharge in the environment was strengthened, in Japan, the standards 0.01 mg/I or less has been in force from April 2003. In order to meet the new standard, two technologies for reduction of lead dissolution into the drinking water have been developed in Japan; substitution of lead free copper alloys for lead bearing bronze (JIS-CAC406) and introduction of surface treatment technology. This technological trend was shortly reviewed. For development of lead free copper alloy casting, mechanical properties, castability and machinability of various lead free alloy castings were examined. Trial alloys used were commercially available ones such as the lead free bronze containing Bi, the lead free bronze containing Bi-Se, the lead free bronze containing Bi-Sb and the lead free brass containing Si. Mechanical properties of alloys were dependent on the pouring temperature and castings thickness and were generally less than those of tin bronze castings (JIS-CAC406, Cu-5 wt% Sn-5 wt% Zn-5 wt% Pb). The machinability of the lead free bronze containing Bi and Se was better than that of the lead free bronze castings containing Bi and Bi-Sb. But was still 10 to 15 % less than that of JIS-CAC406. In a lead free alloy substituted by Bi, adjustment of tin, zinc and bismuth contents was attempted and in the Bi-Se system, the adequate adjustment, for bismuth and selenium contents and also for tin, zinc and bismuth contents, was attempted. New alloy in which the mechanical properties sufficiently satisfy the standard for JIS-CAC406 is developed.

Effect of high intensity ultrasonic treatment on microstructural modification and hardness of a nickel-aluminum bronze alloy

The effect of high intensity ultrasonic treatment (HIUST) at different pouring temperatures for the application time of 100 s on microstructural modification and hardness of a nickel-aluminum bronze (NAB) alloy has been studied. The chemical composition of the investigated alloy is Cu-10Al-5Fe-5Ni. The results show clearly that in the absence of HIUST, the coarser dendritic α(Cu) phases and coarser β′ phases are formed with a nonuniform distribution of coarser intermetallic κII phase particles which are based on Fe3Al in the interdendritic regions. Upon HIUST of this alloy during solidification process, finer equiaxed α(Cu) phases and finer β′ phases with a uniform distribution of finer intermetallic κII phase particles along the cast structure can be obtained at optimum pouring temperature of 1090 °C. The highest hardness of ultrasonic treated alloy can be achieved at the optimum pouring temperature of 1090 °C. The refinement and modification mechanisms resulting in development of microstructure are also investigated.

Analysis of Filling in Thin Section by FEM Based Simulation for LM6 Material

This paper deals with the cooling characteristics of LM6 alloy used as a pouring material for manufacturing of thin hollow rectangular section during the solidification process inside the mold. For purpose of an accurate mathematical modeling, it is essential to establish appropriate gating design and pouring temperature. Here simulation experimental study is carried out by using Pro CAST 2009.0 for LM6 alloy. In this investigation pouring is done on thin rectangular section at different pouring temperature and sprue height. Finally a comprehensive analysis result shows that for efficient casting, pouring temperature is more significant parameter as compared to sprue height.

Weibull analysis of effect of T6 heat treatment on fracture strength of AM60B magnesium alloy

Abstract The effect of T6 heat treatment on the fracture strength and reliability of AM60B alloy was studied. The tensile specimens were poured at three different temperatures of 670, 685 and 700 °C for different holding times of 5, 10 and 15 min. The fluidity test was also conducted to determine the fluidity length under different pouring temperatures and holding times. According to the results, the optimum pouring temperature and holding time were determined as 685 °C and 10 min, respectively. SEM fractography of the tensile specimens reveals that the entrained oxides and oxide-related porosities are the main factors responsible for the reduction of fracture strength under the non-optimal casting conditions. The Weibull statistical approach was used to quantify the scatter of fracture strength in as-cast and heat-treated conditions. For this purpose, T6 schedule was applied to the specimens prepared under the optimal casting condition. It is found that, despite minor effect on the average fracture strength, T6 heat treatment improves the reliability of castings, where the Weibull modulus is increased by 75%. According to the microstructural and fractography observations, this improvement is related to the evolution of more uniform microstructure and the elimination of coarse brittle β-particles in heat-treated samples.

Investigation of porosity in Al casting

Porosity is one of the serious problems observed in foundries. In the present study pure aluminium (99.85%) is used as a cast material. For both simulation and experimental work, it has been seen that due to the pouring temperature, pouring time and different types of gating system design, porosity in the casting is greatly influenced. Here optimization of pouring temperature, pouring time and gating design is done by using Auto-CAST simulation technique. Finally, experimental results are validated with Auto-CAST simulation results and improvements are suggested in terms of optimisation of gating system by modelling and simulation technique. Non-destructive method of testing like dye-penetrant test has been used for checking the surface defects and ultrosonic method of testing has been used for evaluating the presence of subsurface defects.