A Control of Microstructure of A356 Alloy by Sequential Semi-Solid Process

2008 ◽  
Vol 141-143 ◽  
pp. 569-573
Author(s):  
Sung Chul Lim ◽  
Hai Joong Lee ◽  
Jang Won Kang ◽  
Sang Kil Lee ◽  
Kyung Hoon Kim ◽  
...  
Keyword(s):  
Die Casting ◽  
A356 Alloy ◽  
Flow Characteristics ◽  
Solid Particles ◽  
Electromagnetic Stirring ◽  
Cast Sample ◽  
Maintenance Time ◽  
Semi Solid ◽  
Original Strength ◽  
Electronic Parts

The study on rheocasting has been conducted based on examination for destruction, growth, ripening of solid state in accordance with various changes in cooling. And flow characteristics of slurry for high liquid range rather than practical use has gotten attention. However, the characteristics of existing rheocasting and thixocasting are better mechanical property than competing process die casting but it’s competitiveness as automotive or electric electronic parts which cost of product is important. And productivity also has been decreased. Because die-casting techniques has been advanced such as vacuum, mold auto temperature control etc. Most of the work reported at this conference concerned the semi-solid processing of low melting point alloys, and in particular light alloys of aluminum and magnesium. Therefore, the aim of this study is to devise the original strength of semi-solid process by sequential semi-solid process. The size of primary solid particle and the degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were observed. By applying electromagnetic stirring, primary solid particles became finer and rounder relative to as-cast sample. With this background, this research conducted electromagnetic stirring through slurry deliverance of sequential process through A356 alloy electromagnetic stirring pump (30Hz, 130A) with Sequential Semi-Solid Process device to assess the microstructures, primary particle size, degree of sphericity change in A356 alloy in accordance of solid-fraction, stirring speed, and stirring maintenance time.

Numerical Simulation on the Filling Process of Rheological Die Casting and Forming Defects Analysis

2012 ◽  
Vol 192-193 ◽  
pp. 293-298 ◽  
Author(s):  
Fan Zhang ◽  
Nan Nan Song ◽  
Jun Zhang ◽  
Yong Lin Kang ◽  
Qiang Zhu
Keyword(s):  
Numerical Simulation ◽  
Die Casting ◽  
A356 Alloy ◽  
Casting Process ◽  
Solid Particles ◽  
Filling Process ◽  
Die Casting Process ◽  
Defects Analysis ◽  
Semi Solid ◽  
Forming Defects

According to semi-solid slurry rheological behavior, an apparent viscosity model of A356 alloy developed based on the Carreau model was established to simulate filling process of rheo-diecasting about automobile shock absorber parts and to compare with conventional liquid filling process. Numerical simulation results showed that the filling process of rheo-diecasting was smooth but difficult to splash, which reduced the tendency of the alloy oxidation and inclusion. Meanwhile, a certain percentage of the primary solid particles precipitated before filling and solidification shrinkage of semi-solid slurry were small. This benefited to reduce or eliminate shrinkage defects of the castings. Compared with conventional liquid die casting process, rheo-diecasting process had unique advantages in reducing the internal defects and improving mechanical properties of castings.

Control of Semi-Solid Microstructure of AZ91D Mg Alloys by the Electromagnetic Stirring

2006 ◽  
Vol 116-117 ◽  
pp. 546-549
Author(s):  
Sung Chul Lim ◽  
Heung Bok Lee ◽  
Kyung Hoon Kim ◽  
Hyouk Chon Kwon
Keyword(s):  
Melting Point ◽  
Cooling Rate ◽  
Solid Particle ◽  
Hold Time ◽  
Solid Particles ◽  
Mg Alloys ◽  
Electromagnetic Stirring ◽  
Cast Sample ◽  
Specific Strength ◽  
Semi Solid

Most of the work reported at this conference concerned the semi-solid processing of low melting point alloys, and in particular light alloys of aluminum and magnesium. Mg alloys are very attractive as structural materials, because they are the lightest metal among all structural metal materials and excellent specific strength. The purpose of this paper is to develop a semi-solid microstructure of Mg alloys using electromagnetic stirring applicable for lighter automobile. The size of primary solid particle and the degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were observed. By applying electromagnetic stirring, primary solid particles became finer and rounder relative to as-cast sample. As the input Hz increased from 10Hz to 14Hz, particle size decreased. The size of primary solid particle was found to be decreased with increasing cooling rate. Also, it decreased with stirring up to 3 minutes but increased above that point. The degree of sphericity became closer to be 1 with hold time. Semi-solid microstructure of Mg alloys, one of the low melting point alloys, could be controlled by electromagnetic stirring.

Analytical Model for Heat Transfer Phenomena in Cup-Cast Method

2006 ◽  
Vol 116-117 ◽  
pp. 569-572
Author(s):  
Farshid Pahlevani ◽  
J. Yaokawa ◽  
M. Itamura ◽  
M. Kikuchi ◽  
O. Nagasawa ◽  
...  
Keyword(s):  
Heat Transfer ◽  
A356 Alloy ◽  
Nucleation And Growth ◽  
Heat Transfer Model ◽  
Solid Particles ◽  
Transfer Model ◽  
Heat Transfer Phenomenon ◽  
Semi Solid ◽  
Slurry Preparation ◽  
Good Agreement

Cup-cast method is a new method deals with semi-solid slurry preparation recently developed by the authors. In this method, suspension of globular solid particles in molten metal is prepared by controlling the nucleation and growth of solid-particles through the simplest and quickest techniques. In this method, heat transfer phenomenon plays an important role in governing the shape, size, and fraction of solid particles. In the current study, a heat transfer model was proposed and applied to Al-A356 alloy semi-solid slurry preparation. The heat transfer model was based on heat balance consideration between cup and slurry and it was in a good agreement with experimental results.

The Effect of Electromagnetic Stirring on the Semi-Solid Microstructure of High-Melting Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 542-545
Author(s):  
Sung Chul Lim ◽  
Heung Bok Lee ◽  
Kyung Hoon Kim ◽  
Hyouk Chon Kwon
Keyword(s):  
Melting Point ◽  
Cooling Rate ◽  
Solid Particle ◽  
Hold Time ◽  
Solid Particles ◽  
Electromagnetic Stirring ◽  
High Melting ◽  
Cu Alloys ◽  
Semi Solid ◽  
Cage Rotor

Most of the work reported at this conference concerned the semi-solid processing of low melting point alloys, and in particular light alloys of aluminum and magnesium. It also can be true for the higher melting point alloys, such as Cu alloys. The purpose of this paper is to develop a semi-solid microstructure of Cu alloys using electromagnetic stirring applicable for squirrel cage rotor of induction motor. The size of primary solid particle and the degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were observed. By applying electromagnetic stirring, primary solid particles became finer and rounder relative to as-cast sample. As the input Hz increased from 30Hz to 40Hz, particle size decreased. The size of primary solid particle was found to be decreased with increasing cooling rate. Also, it decreased with stirring up to 3 minutes but increased above that point. The degree of sphericity became closer to be 1 with hold time. Semi-solid microstructure of Cu alloys, one of the high melting point alloys, could be controlled by electromagnetic stirring.

Study on Microstructures and Mechanical Properties of Rheo-Die Casting Semi-Solid A356 Aluminum Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 453-456 ◽  
Author(s):  
Yong Lin Kang ◽  
Yue Xu ◽  
Zhao Hui Wang
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Die Casting ◽  
A356 Alloy ◽  
Experimental Results ◽  
A356 Aluminum Alloy ◽  
Microstructures And Mechanical Properties ◽  
A356 Aluminum ◽  
Semi Solid

In this paper, with a newly self-developed rotating barrel rheomoulding machine(RBRM), microstructures and mechanical properties of rheo-die casting A356 alloy were studied. In order to clearly show the characteristic of rheo-die casting, liquid die casting and semi-solid casting were done too. The experimental results showed that microstructures of rheo-die casting were composed of solid grains, which were finer and rounder, and had fewer pores. In the three technologies, integrated mechanical properties of semi-solid rheo-die casting were the best.

A Compound Process Preparing Semi-Solid A356 Alloy Slurry

2010 ◽  
Vol 97-101 ◽  
pp. 1003-1007 ◽  
Author(s):  
Zheng Liu ◽  
Wei Min Mao
Keyword(s):  
Grain Size ◽  
Nucleation Rate ◽  
A356 Alloy ◽  
Electromagnetic Stirring ◽  
Structure Morphology ◽  
Compound Process ◽  
Semi Solid ◽  
Low Superheat

The semi-solid A356 alloy slurry is prepared by compound process, and the effect of the compound process on morphology and size of primary α-Al in A356 alloy is researched. The results indicate that the compound process remarkably affects the morphology and the size of primary α-Al. Primary α-Al with particle-like is distributed uniformly in A356 alloy, and there is no the transient area of change in structure morphology. Compared with the samples prepared by low superheat pouring and slightly electromagnetic stirring, the nucleation rate, morphology and grain size of primary α-Al in A356 alloy are markedly improved by the compound process. The mechanism of refining grain in the compound process is probed.

Microstructural Investigation of Semisolid Aluminum A356 Alloy Prepared by the Combination of Electromagnetic Stirring and Gas Induction

2019 ◽  
Vol 285 ◽  
pp. 290-295
Author(s):  
Nora Nafari ◽  
Farnoush Yekani ◽  
Hossein Aashuri
Keyword(s):  
Aspect Ratio ◽  
Shape Factor ◽  
A356 Alloy ◽  
Average Diameter ◽  
Electromagnetic Stirring ◽  
Microstructural Investigation ◽  
Porous Graphite ◽  
Three Phase ◽  
Semi Solid ◽  
Aluminum A356 Alloy

A three phase electromagnetic stirrer was used to agitate aluminum A356 slurry and a dry and oxygen free argon gas was introduced in to the slurry by a porous graphite core at a same time. The prepared semi-solid slurry was then transferred into a metallic mold and was compacted by a drop weight. Results demonstrated a favorable increase in shape factor, decrease in aspect ratio and average diameter size at different intensities of stirring. The intensity of stirring was changed by altering the current passed through the magnetic coil and also bubbling intensity via the porous graphite diffuser. Different time intervals for electromagnetic stirring and gas induction were applied. Agitating the slurry for 90 Sec. separately by electromagnetic stirrer and GISS method, gave better results in terms of shape factor, decrease in average diameter of the globules and aspect ratio.

Development of Microstructure of Semi-Solid A356 Alloy by Alternating Electromagnetic Stirring

2011 ◽  
Vol 266 ◽  
pp. 84-88
Author(s):  
Wen Liu ◽  
Ji Qiang Li ◽  
Xu Ding
Keyword(s):  
Particle Diameter ◽  
A356 Alloy ◽  
Good Method ◽  
Processing Parameters ◽  
Electromagnetic Stirring ◽  
Isothermal Treatment ◽  
Average Particle ◽  
Shape Coefficient ◽  
Magnetic Stirring ◽  
Semi Solid

The influence of processing parameters on the semi-solid microstructure has been investigated in the course of semi-solid slurry preparation of A356 aluminum alloy by alternating electromagnetic stirring. The results show that compared with horizontal, vertical and spiral magnetic stirring method, alternating magnetic stirring could make eligible slurry with finer, more equiaxed and more homogeneous primary α particles in much shorter time. The microstructure evolution during isothermal treatment is studied and it is shown that the average particle diameter increases with the holding time and the shape coefficient decreases somewhat at first, and then decreases sharply in the end. It is discovered that alternating electromagnetic stirring is a good method to prepare semi-solid slurry with fine and relatively round primary particles.

The Microstructure Evolvement and Simulation Analysis during Semi-Solid Processing of Aluminum Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 139-144 ◽  
Author(s):  
Yi Tao Yang ◽  
Jian Fu Wang ◽  
Heng Hua Zhang ◽  
Guang Jie Shao
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
General Structure ◽  
Die Casting ◽  
Fluid Velocity ◽  
Solid Particles ◽  
Forming Process ◽  
Unequal Distribution ◽  
Semi Solid ◽  
Die Castings

To enhance the comprehension on the internal rule of microstructure evolvement and quality-controlled relativity, the microstructure during the induction reheating of billets and die casting of parts was systematically investigated. According to general structure observation and aided analysis of some computer simulations, the quantitative relationships between microscopic morphology (including solid fraction and grain shape) and formation state was minutely discussed. The experimental results showed that liquid and solid phase in semi-solid slurry had different filling tendency, fluid velocity of liquid phase in the area of high filling speed was relative quick and easy to flow into far area and corner. Solid particles far from gate possessed fine and round grain. Moreover, the structure configuration of original billets markedly affected forming process; billets with fine and round grain were required for the die-castings of complex shape and thin thickness. In the case of the big change in shape and thickness of die-castings, the design of gating system and the control of plunger speed should be so properly carried out as to avoid unequal distribution of solid and liquid phase in die-casting part as soon as possible.

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