Semi-continuous Casting Process Research Articles

Ultrasonic Bending Vibration-Assisted Purification Experimental Study of 7085 Aluminum Alloy Melt.

Aiming at the problem that melt inclusions in the casting process of 7085 aluminum alloy seriously affect the ingot quality, this study introduces ultrasonic bending vibration into the melt of the launder in the semi-continuous casting process of 7085 aluminum alloy and investigates the online purification effect of ultrasonic bending vibration on the melt of 7085 aluminum alloy through a metallographic analysis, SEM analysis, and EDS energy spectrum analysis. The results show that, under the action of the ultrasonic, the inclusions in the aluminum melt are transformed from a large number of elongated large inclusions with a size of more than 50 μm, and granular inclusions with a size of about 5–15 μm, into a small amount of smaller than 30 μm point-like small inclusions. In addition, the average area ratio of inclusions in the melted sample was reduced from 3.835 (±0.05)% to 0.458 (±0.05)%, and the residual refining agent in the aluminum melt was effectively removed. It was also found that under the action of ultrasonic bending vibration, the tiny inclusions in the melt aggregate with each other, and interact with the residual refining agent in the melt to further grow, and are attached to the inner surface of the ceramic cavity channel to be removed.

On Numerical Simulation of Casting in New Foundries: Dynamic Process Simulations

New and more complex casting technologies are growing, and foundries are using innovative methods to reduce cost and energy consumption and improve their product qualities. Numerical techniques, as tools to design and examine the process improvements, are also evolving continuously to embrace modelling of more dynamic systems for industrial applications. This paper will present a fresh approach towards the numerical simulation of dynamic processes using an evolving and dynamic mesh technique. While the conventional numerical techniques have been employed for these dynamic processes using a fixed domain approach, the more realistic evolving approach is used herein to match the complex material processes in new foundries. The underpinning of this new dynamic approach is highlighted by an evolving simulation environment where multiple mesh entities are appended to the existing numerical domain at timesteps. Furthermore, the change of the boundary and energy sources within casting process simulations have rationally been presented and its profound effects on the computational time and resources have been examined. The discretization and solver computational features of the technique are presented and the evolution of the casting domain (including its material and energy contents) during the process is described for semi-continuous casting process applications.

Effect of Low-Frequency Electromagnetic Casting on Micro-Structure and Macro-Segregation of 5A90 Alloy Ingots.

The effect of low-frequency electromagnetic fields on the micro-structure and macro-segregation of 5A90 alloy ingots during the semi-continuous casting process were quantitatively investigated. The ingots of a 5A90 alloy with a diameter 170 mm were produced by the conventional direct chill casting (DCC) process and low-frequency electromagnetic casting (LFEC) with 10 Hz/100 A. The results showed that LFEC can substantially refine the micro-structure and shorten the width of the columnar grain area of an ingot. The refinement effect came with the relieving of grain boundary segregation and an improvement in the macro-segregation of the ingot. Compared with the traditional DCC process, the tensile properties of the aged alloy prepared by the LFEC process were improved due to the effects of the increase in solid solubility and the strengthening of the grain refinement, so that the stability of the tensile properties was also improved. Meanwhile, the rate of yield increased by 2.3% with a decrease in the peeling thickness of the ingot.

Casting methods for the production of rotationally symmetric copper bimetals

ABSTRACT Multiple-material products are characterised by a complex property profile which is achieved by combining the particular advantages of at least two different materials. Bimetal casting is an energy- and material-efficient technology for the production of multi-metallic objects. This paper describes the development of a semi-continuous casting process for the formation of a rotationally symmetric bimetal with a cohesive bonding character at the interface of a copper–tin alloy (CuSn6) and pure copper (Cu99.5). Initial experiments are conducted by static casting to evaluate the thermal process window. Based on the results of the initial experiments, a vertical semi-continuous compound casting process is developed. A stable cohesive bond between the joining partners is accomplished by forming a solid solution at the interface. This paper is part of a Thematic Issue on Copper and its Alloys.

Effects of Electromagnetic Agitation on Crystal Growth during the Pure Aluminum Slow Cooling Process

Refining grains are important to obtain sound cast billets suitable for further processing. The structure refinement of low frequency electromagnetic field (LFEF) during the aluminum alloy semi-continuous casting process has been confirmed by many researchers. In this work, effects of the electromagnetic agitation on the crystal growth were investigated during the pure aluminum slow cooling process. The results showed that the grain refinement effect by electromagnetic agitation mainly occurred at the first half period of crystal growth. With increasing of applying LFEF treated time, the fine grain occupied the whole section of ingot, and the ratio of fine grain zone to the whole section was proportional to the treated time.

Effect of Ultrasonic Bending Vibration Introduced by the L-shaped Ultrasonic Rod on Solidification Structure and Segregation of Large 2A14 Ingots.

In order to achieve long-term and stable ultrasonic treatment in the direct chill semi-continuous casting process, a new L-shaped ceramic ultrasonic wave guide rod is designed to introduce ultrasonic bending vibration into 2A14 aluminum alloy melt. The effect of ultrasonic bending vibration on the solidification structure and composition segregation of large 2A14 aluminum alloy ingots (φ 830 mm × 6000 mm) in the process of semi-continuous casting were studied by means of a direct reading spectrometer, scanning electron microscope, metallographic microscope, and hardness test. The ultrasonic ingot treated by bending vibration was compared with the ingot without ultrasonic treatment and the ingot treated by the traditional straight-rod titanium alloy wave guide rod. The results show that, during the solidification of 2A14 aluminum alloy, ultrasonic treatment can significantly refine the grain, break up the agglomerated secondary phase, and make its distribution uniform. The macro-segregation degree of solute including the negative segregation at the edge of the ingots and the positive segregation in the center can be reduced. Through comparative analysis, the macrostructure of the ingot, treated by the L-shaped ceramic ultrasonic wave guide rod, was found to be better than that of the ingot treated by the traditional straight-rod titanium alloy wave guide rod. In particular, the grain refinement effect at the edge of the ingot was the best, the secondary phase was smaller, more solute elements can be dissolved into the α-Al matrix, and the ability of the L-shaped ultrasonic wave guide rod to restrain segregation was stronger at the edge of the ingot.

Effect of electromagnetic casting process on microstructure and properties of AZ31 magnesium alloy

ABSTRACTIn this paper, AZ31 magnesium alloy is cast by applying the semi-continuous casting process with a low-frequency electromagnetic field. By studying the influence of electromagnetic field frequency, excitation current intensity and casting velocity on the microstructure and mechanical properties, the optimum process under oil-slip electromagnetic casting conditions was determined to improve the degree of grain refinement, yield strength, elongation and tensile strength of AZ31 alloy. An improved microstructure refining effect and higher hardness can be obtained with a current intensity af 60 A. The microstructures and mechanical properties obtained for different casting velocities of V = 200 mm/min and V = 230 mm/min at processing parameters of f = 30 Hz and I = 120 A were compared. Our results suggest that a higher casting speed does not lead to grain refinement or improved mechanical properties. Frequency

Effect of B4C particle size on the mechanical properties of B4C reinforced aluminum matrix layered composite

Abstract Reinforcement particle size is very important for the performance of metal ceramic composites. This work studied the influence of B4C particle size on the mechanical properties of Al matrix layered composites. These composites were fabricated using a simplified semicontinuous casting and hot-rolling process. To obtain an optimized filling structure of particles, Horsfield filling principle was applied to determine the size and mass fraction of B4C particles. Four sizes of B4C particles were used with various combinations. The results showed that with the increase of the B4C particle size and fine B4C mass fraction, the hardness of the composites decreases whereas the impact strength and ultimate tensile strength increase. The residual stress at interface should be responsible for the variation in properties. Besides, the interparticle distance also contributes to the change in impact strength and ultimate tensile strength.

Comparación y Efecto del Homogenizado en Billets de Aluminio AA 6063

The lack of comparative studies about the distribution of the main alloying elements along aluminum billet´s AA 6063 widely use in extrusion companies to produce aluminum profiles, It makes necessary to counterpoise the difference between homogenized billet produced in horizontal continuous casting machine and a billet produced in vertical semi-continuous casting process. Applying spectrometric tests to quantify the weight percent of main alloying elements, brings out its own nature of each production process on every billet. Nevertheless, helped out by a metallographic test reveals in one billet the negative effect of an inadequate process of homogenization after the heat treatment process T5 in the aluminum profiles that holds it back to reach an adequate Webster hardness related to quality assurance. It reflects that is not enough to have a billet with a uniform chemical composition but the importance of an adequate billet´s heat treatment in order to be use in the extrusion process.Keywords: AA 6063, Billet, Comparison, Homogenized

Microstructural and Mechanical Characteristics of Cladding Billets with Different Clad Ratios

AA4045/AA3003 cladding billets with different clad ratios were fabricated by direct chill casting process. The macrostructures, microstructures, compositions distribution and the mechanical properties near the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. The metallurgical bonding was formed due to the diffusions of elements. The decreasing of clad ratio changed the microstructure at the interface and reduced the thickness of diffusion layer. The hardness around the interface is higher than that of AA3003 side but lower than that of the other side, indicating that the interface yield strength is also higher than that of AA3003. After extrusion process, the characteristics of the interface remain that of as-cast cladding billet.

Interfacial characteristics and properties of a low-clad-ratio AA4045/AA3003 cladding billet fabricated by semi-continuous casting

A low-clad-ratio AA4045/AA3003 cladding billet was fabricated using a semi-continuous casting process and was subsequently extruded indirectly into a cladding pipe. The temperature distribution near the interface was measured. The microstructures, elemental distribution, Vickers hardness around the bonding interface, and the interfacial shear strength were examined. The results showed that the interface temperature rebounded when AA4045 melt contacted the supporting layer. The two alloys bonded well, with few defects, via the diffusion of Si and Mn in the temperature range from 569°C to 632°C. The mean shear strength of the bonding interface was 82.3 MPa, which was greater than that of AA3003 (75.8 MPa), indicating that the two alloys bonded with each other metallurgically via elemental interdiffusion. Moreover, no relative slip occurred between the two alloys during the extrusion process.

Production of Jumbo Blooms by Semi-continuous Casting: Challenges, Feasibility, and Future Potential

In recent years a continuously increasing demand for the application of continuous casting in the production of medium and high-alloyed steel grades in large formats (called jumbo blooms) has been noticed. Whereas in the past the production of these grades was mainly the domain of ingot casting and remelting processes, continuous casting of such formats was considered rather a niche market and has only very recently been introduced on a larger scale. The present contribution should highlight the different challenges attributed to the production of large rounds. Furthermore, the production feasibility by means of semi-continuous casting process will be explained.

Microstructure and properties at bonding interface of AA4045/AA3003 aluminum alloy cladding billet prepared by semi-continuous casting

AA4045/AA3003 cladding billet was prepared by direct chill semi-continuous casting process. The macrostructures, microstructures, temperature distribution, compositions distribution and the mechanical properties at the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. At the interface, diffusion layer of about 10 μm on average formed between the two alloys due to the diffusion of alloy elements in the temperature range from 596 to 632 °C. From the side of AA4045 to the side of AA3003, the Si content has a trend to decrease, while the Mn content has a trend to increase gradually. Tensile strength of the cladding billet reaches 103.7 MPa, the fractured position is located on the AA3003 side, and the shearing strength is 91.1 MPa, revealing that the two alloys were combined metallurgically by mutual diffusion of alloy elements.

Influence of casting speed on fabricating Al-1%Mn and Al-10%Si alloy clad slab

Abstract In this paper, the effect of casting speed on fabricating Al-1%Mn and Al-10%Si alloy clad slab was investigated. Before the trials with the semi-continuous casting process were conducted, a series of simulation with the engineering software FLUENT was made to forecast the influence of the casting speed on the temperature field and the liquid fraction of the clad slab. The simulation results indicated that the increase of the casting speed reduces the time in the cooling zone, thus the thickness of the Al-1%Mn solidification shell under the dividing plate gets thinner. Based on the simulation results, the Al-1%Mn alloy and Al-10%Si alloy clad slab was successfully produced by semi-continuous casting process. The interface of clad ingots was investigated by methods of metallographic and electron probe microanalysis. The tests on the interface confirmed the simulation results and showed that a clad slab of two different aluminum alloys with excellent metallurgical bonding was achieved by semi-continuous casting. According to the result of the tensile tests, the strength of the specimens remains at 110 MPa, and the fracture position located in the Al-1%Mn alloy indicates that the strength of the interface is higher than that of the Al-1%Mn alloy.

Three-Layer Al/Al–B4C Composite Material Prepared by Casting and Hot Rolling

Casting and hot rolling are proposed to verify a semi-continuous casting and hot rolling process to produce a three-layer Al/Al–B 4 C metal-cermet composite. The outer layer is pure Al, the inner layer is Al matrix composite reinforced with B 4 C particles (the mass fraction of Al and B 4 C are 62.36 and 37.64%, respectively). The results show that the reinforced particles are distributed in the inner layer homogeneously, and both layers are sintered together with no pores or flaws. The clad ratios of the composites of 26, 5, 3, and 1 mm are 50.28, 54.67, 61.23, and 57.46%, respectively. The Vickers hardness varies from 46 HV for the outer pure aluminum layer to 158 HV for the inner composite layer in 3 mm specimen, indicating totally different properties in different layers.

Study on Composite Interface of 4045/3003 by Cladding Casting

With the cladding casting equipment, which was self-designed and self-made, 4045/3003 composite ingot, which is in size of Φ140mm/Φ110mm, has been manufactured by direct cooling continuous casting by adjusting and optimizing the technological parameters. The process was investigated involving macro-morphology and microstructure near the interface between the two different aluminum alloys at different positions, and distributions of both components and hardness of the cladding ingot. In addition, the tensile strengths were tested. The results showed that metallurgical bonding of two different aluminum alloys could be obtained by direct-chill semi-continuous casting process. The diffusion layer, which is about 15μm on average, has formed on the two sides of composite interface during casting process. From the side of 4045 aluminum alloy to the side of 3003 aluminum alloy, the Si content has a trend to decrease, as well as the hardness, while the Mn content has a trend to increase gradually. Tensile strength of the coated ingot reaches 117.3MPa, which is higher than the core-material matrix (3003 aluminum alloy), indicating the bonding of the two alloys belongs to metallurgical bonding.

404 半連続鋳造法で作製したマグネシウム合金厚板の熱間鍛造(OS4-(1),OS4 オーガナイズドセッション≪材料・組織と加工≫)

This study revealed the possibility of hot forging of AZ131 magnesium alloy thick plate prepared by semi-continuous casting method. Semi-continuous casting process has a beneficial effect on producing thick plate for forging. AZ131 magnesium alloy has high strength and quite small elongation compared the general plastic magnesium alloy, however the forging ability of AZ131 is not clear. Pin type die was used to research the forging ability of AZ131 magnesium alloy. Results are below. It was possible to forge the AZ131 magnesium alloy thick plate prepared by semi-continuous casting. Some cracks were observed on the surface of forging at 350℃. Cracks were free on the surface of forging at 300℃ and the AZ131 magnesium alloy were filled up in the die. It was suggested that forging at lower temperature was effective to prevent the cracking.

Characteristics of 2024/3003 aluminium alloys bimetal prepared by direct chill casting

A direct chill semicontinuous casting process to prepare 2024/3003 clad slab has been developed in the present study. Microstructure, solute distribution and bonding strength of the interfacial regions of clad slab were investigated by methods of metallographic examination, electron probe microanalysis and tensile tests. The results show that an excellent metallurgical bonding between the two different alloys can be achieved with optimal parameters. The 3003 alloy, which was poured into the mould earlier, serves as the substrate of heterogeneous nucleation of 2024 alloy. The Cu and Mg atoms diffuse from the 2024 side into the matrix of 3003 side, while Mn atoms diffuse in the opposite direction. The mean tensile strength of clad slab is 118 MPa, and the strength of the interface is higher than that of 3003 alloy.

Formation of Structure and Properties in Casting Processes on the Example of AZ91 Magnesium Alloy

Abstract Contemporary materials engineering requires the use of materials characterised by high mechanical properties, as these precisely properties determine the choice of material for parts of machinery and equipment. Owing to these properties it is possible to reduce the weight and, consequently, the consumption of both material and energy. Trying to meet these expectations, the designers are increasingly looking for solutions in the application of magnesium alloys as materials offering a very beneficial strength-to-weight ratio. However, besides alloying elements, the properties are to a great extent shaped by the solidification conditions and related structure. The process of structure formation depends on the choice of casting method forced by the specific properties of casting or by the specific intended use of final product. The article presents a comparison of AZ91 magnesium alloys processed by different casting technologies. A short characteristic was offered for materials processed by the traditional semi-continuous casting process, which uses the solidification rates comprised in a range of 5 - 20°C/s, and for materials made in the process of Rapid Solidification, where the solidification rate can reach 106 °C/s. As a result of the casting process, a feedstock in the form of billets and thin strips was obtained and was subjected next to the process of plastic forming. The article presents the results of structural analysis of the final product. The mechanical properties of the ø7 mm extruded rods were also evaluated and compared.

As-cast structure of DC casting 7075 aluminum alloy obtained under dual-frequency electromagnetic field

We have experimentally determined the as-cast structures of semi-continuous casting 7075 aluminum alloy obtained in the presence of dual-frequency electromagnetic field. Results suggest that the use of dual-frequency electromagnetic field during the semi-continuous casting process of 7075 aluminum alloy ingots reduces the thickness of the surface segregation layer, increases the height of the melt meniscus, enhances the surface quality of the ingot, and changes the surface morphology of the melt pool. Moreover, low-frequency electromagnetic field was found to show the most obvious influence on improving the as-cast structure because of its high permeability in conductors.