scholarly journals Study on Solidification Structure Evolution of Direct-Chill Casting High Purity Copper Billet Using Cellular Automaton-Finite Element Method

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1052
Author(s):  
Yonghui Jia ◽  
Dazhi Zhao ◽  
Chunyu Li ◽  
Lei Bao ◽  
Qichi Le ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Grain Size ◽  
Finite Element ◽  
High Purity ◽  
Direct Chill ◽  
Solidification Structure ◽  
Structure Evolution ◽  
Dc Casting ◽  
Solid Liquid ◽  
Purity Copper

A heat transfer model and a cellular Automation-Finite Element (CAFE) coupling model were established to analyze the solid/liquid (S/L) interface and solidification structure evolution of high purity copper Direct-chill (DC) casting billet under different casting conditions. The simulation and actual experimental results of liquid sump shape and solidification structure were first compared to verify the accuracy of the model. It is proved that the model is effective for simulating the solidification structure of the actual DC casting high purity copper billet. After that, the model was used to predict the solidification structure under different casting temperatures, casting speeds, and heat transfer coefficients. It is shown that, with the increase of casting temperature, the grain size decreases first and then increases. There is a compromise between grain size and its uniformity, and the grain size is more uniform at higher casting temperature. With the increase of casting speed, the depth of liquid sump and the height of the S/L interface increase, but the total grain number of the billet cross-section decreases gradually. As the heat transfer coefficient increases, the depth of the casting liquid sump becomes shallow, but the height of the solid-liquid interface increases and the grain size increases gradually. For the preparation of high purity copper billets with large cross-sectional dimensions by DC casting, a fine solidified structure could be obtained by appropriately reducing the casting speed and cooling intensity.

Modelling of the Metal/Mould Interactions in the DC Casting Process for Aluminium and Magnesium

2010 ◽  
Vol 654-656 ◽  
pp. 783-786 ◽  
Author(s):  
Arvin Prasad ◽  
Ian F. Bainbridge
Keyword(s):  
Heat Transfer ◽  
Casting Process ◽  
Direct Chill ◽  
Heat Extraction ◽  
Small Scale ◽  
Wall Region ◽  
Wall Heat Transfer ◽  
Mould Wall ◽  
Dc Casting ◽  
Basic Features

The process of direct chill (DC) casting of aluminium and magnesium alloys is regarded as a mature technology. The thrust of more recent work to understand and upgrade the technology has been centred on developing models of the process, the most advanced of which (e.g., Alsim and Calcasoft) have been used to examine what may be considered macro-features of the process (macro-segregation, hot cracking, etc.). These models, being macroscopic, rarely elaborate on the role of mould-wall heat transfer in the DC casting process. As part of the work on DC casting being conducted at CAST, for the investigation of small scale features of the process (e.g. heat extraction through the mould wall), a 2D finite Difference model of the process near the mould-wall region has been developed. The basic features of the model are described and initial results outlined.In particular, the effect of mould-wall heat transfer on the solid shell formed during the steady state regime of DC casting will be presented.

Application Research of a New Coupling Stirring on DC Casting Process for Large-Sized Aluminum Ingots

2015 ◽  
Vol 817 ◽  
pp. 48-54 ◽  
Author(s):  
Hai Jun Wang ◽  
Jun Xu ◽  
Zhi Feng Zhang ◽  
Bo Liang ◽  
Ming Wei Gao
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Casting Process ◽  
Direct Chill ◽  
Application Research ◽  
Center Position ◽  
Composition Segregation ◽  
Dc Casting ◽  
The Difference ◽  
7075 Alloy

A new coupling stirring technology was proposed and used to prepare direct chill (DC) ingots. Ingots of 7075 alloy were produced by a process of normal direct chill (NDC) casting and coupling-stirring direct chill (CDC) casting, respectively. The effect of the technology on the microstructures, composition segregation and mechanical properties of the ingots was investigated. The results showed that the temperature variation in the CDC casting process was more uniform than that in the NDC casting process. The grain of the CDC ingots was finer and more spherical than the grain of NDC ingots. The grain size at the edge, 1/2 radius, and center position in CDC ingot decrease by 28%, 22%, and 24% comparing with the grain size of the corresponding positions of NDC ingot, respectively. The billets with higher performance and lower macro-segregation were obtained in case of CDC. The flow stresses and the difference in different positions of DC ingots measured at Gleeble-1500D thermo-mechanical simulator decreased obviously when the coupling stirring technology is used in the casting process.

A Comparison Between 3-D Thermal Model and 3-D CFD Model for Vertical DC Casting of Rolling Ingots of Aluminum Alloy 7050

2014 ◽  
Author(s):  
Mainul Hasan ◽  
Latifa Begum
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
Thermal Model ◽  
Casting Process ◽  
Direct Chill ◽  
Turbulent Heat Transfer ◽  
Mushy Region ◽  
Turbulent Heat ◽  
Cfd Model ◽  
Dc Casting

In this study, first a 3-D thermal model is developed for an open top, vertical direct chill (DC) casting process of rolling slabs (ingots) by taking into account the casting speed in the form of slag flow in the thermal connective-diffusion equation. The mushy region solidification characteristics of the process are accounted for through the implementation of the enthalpy porosity technique. The thermal model is later extended to a 3-D CFD model to account for the coupled turbulent heat transfer and solidification aspect of the process. Both models simulate an industrial-sized, hot-top type vertical Direct Chill (DC) slab caster for high strength aluminum alloy AA-7050. A staggered control volume based finite-difference scheme is used to solve the modeled equations and the associated boundary conditions. In the CFD model, the turbulent aspects of flow and solidification heat transfer are modeled using a low Reynolds number version of the k–ε eddy viscosity approach. Computed results for the steady-state phase of the casting process are presented for four casting speeds varying from 60 to 180 mm/min for a fixed inlet melt superheat of 32°C. Simulation results of the velocity and temperature fields and heat fluxes along the caster surface are presented for the CFD model and the shell thickness and sump depth are compared between the CFD and thermal models.

Effect of Forging Temperature on Deformability and Structure Evolution of High Purity Aluminium during Multi-Directional Forging Process

2016 ◽  
Vol 877 ◽  
pp. 371-379 ◽  
Author(s):  
Qing Feng Zhu ◽  
Jia Wang ◽  
Lei Li ◽  
Chun Yan Ban ◽  
Zhi Hao Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
High Purity ◽  
Recrystallization Temperature ◽  
Structure Evolution ◽  
Inhomogeneous Deformation ◽  
Forging Process ◽  
Fine Grain ◽  
Sample Shape ◽  
Purity Aluminium ◽  
High Purity Aluminium

The effects of final forging temperatures on deformability and structure evolution of high purity aluminum during multi-directional forging process were investigated. The results showed that increasing the initial forging temperature is beneficial for controlling the sample shape in the initial forging passes. Recrystallization during the initial forging passes improves the deformability of the sample in the following low-temperature forging processes. An X-shape fine grain zone is formed in the sample due to the inhomogeneous deformation of multi-directional forging process. When the forging pass is 6, the final forging temperature has an important influence on the grain size in the fine grain zone. The grain size decreases from 302 μm to 60 μm with the final forging temperature decreasing from 310 °C to 65 °C. The X-shape fine grain zone caused by the inhomogeneous deformation cannot be eliminated by increasing the final forging temperature (even higher than the recrystallization temperature of high purity aluminium).

Effect of Casting Velocity on Microstructures of Almg0.9Si0.7 Alloy by Low-Superheat DC Casting

2011 ◽  
Vol 415-417 ◽  
pp. 549-552 ◽  
Author(s):  
Da Zhi Zhao ◽  
Fu Xiao Yu ◽  
Fang Liu ◽  
Ke Zhun He
Keyword(s):  
Dendritic Growth ◽  
Smooth Surface ◽  
Casting Process ◽  
Direct Chill ◽  
Pouring Temperature ◽  
Suitable Temperature ◽  
Dc Casting ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Low Superheat

The billets of AlMg0.9Si0.7 alloy, which were cast through the direct chill (DC) casting process of low superheat, were analyzed to study the effect of casting velocity on the surface quality and the morphology of primary α grains. The results show that the nucleating quantity of primary α grains in the melt is increased obviously due to the low pouring temperature during DC casting of low superheat. The suitable temperature gradient in front of the solid-liquid interface is obtained by changing the casting velocity, and the dendritic growth of the primary α grains is inhibited effectively. The billet of AlMg0.9Si0.7 alloy with smooth surface and homogeneous, fine rosette-shaped grains is obtained at the velocity of 130mm/min.

scholarly journals Structure Refinement Upon Ultrasonic Melt Treatment in a DC Casting Launder

JOM ◽  
2020 ◽  
Vol 72 (11) ◽  
pp. 4071-4081
Author(s):  
Tungky Subroto ◽  
Dmitry G. Eskin ◽  
Christopher Beckwith ◽  
Ivan Skalicky ◽  
Dan Roberts ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Particle Density ◽  
Structure Refinement ◽  
Direct Chill ◽  
Treatment Quality ◽  
Number Density ◽  
Melt Treatment ◽  
Dc Casting ◽  
Ultrasonic Melt Treatment

Abstract This work focuses on ultrasonic melt treatment (UST) in a launder upon pilot-scale direct chill (DC) casting of 152-mm-diameter billets from an AA6XXX alloy with Zr addition. Two casting temperatures (650°C and 665°C) were used to assess their effect on the resulting microstructure (grain size, particle size, and number density). Structure refinement results show the feasibility of UST in the DC casting launder. This is quantified through the corresponding reduction of grain size by around 50% in the billet center, or more towards the billet surface, reduction of the average Al3Zr particle size, and increase in the particle number density. A higher Al3Zr particle density was obtained when the alloy was cast at 665°C. Numerical simulation results and suggestions on how to improve the treatment quality of UST in DC casting launder are also provided.

Research on Grain Refinement Process and Microstructure of Ultra-High Purity Copper Used for Integrated Circuit

2016 ◽  
Vol 852 ◽  
pp. 601-606 ◽  
Author(s):  
Xiang Zeng ◽  
Jin Jiang He ◽  
Xuan Jiang ◽  
Hao Zeng ◽  
Xiao Yong Wan ◽  
...  
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Integrated Circuit ◽  
High Purity ◽  
Large Scale ◽  
Rolling Texture ◽  
Ultra High Purity ◽  
Average Grain Size ◽  
Scale Integration ◽  
Purity Copper

In this paper, the deformation and annealing process of ultra-high purity copper used for Ultra large-scale integration (ULSI) have been investigated. The evolution of grain size and texture during deforming and annealing were analyzed. The results show that the coarse cast structure can be efficiently eliminated by multiple forging and the grain size can be refined initially. Ultra-high purity copper with cold rolling begins to recrystallize at a temperature of 150°C. Especially, when the cold rolling deformation is 80%, the average grain size is about 17.9μm after optimized annealing. The typical rolling textures after deformation are not strong and a large number of low-angle grain boundaries are found. After annealing, the rolling texture and recrystallization texture come to co-existence. The texture distribution is uniform without strong grain orientation and high-angle boundaries demonstrate in the microstructure.

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