• Title/Summary/Keyword: Semi-Solid Alloy

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Effect of Induction Heating Conditions on Globular Microstructure of Al-7%Si-0.3%Mg Alloy for Thixoforming (Thixoforming을 위한 Al-7%Si-0.3%Mg 합금의 유도 가열 조건이 구상화 조직에 미치는 영향)

  • Jung, Hong-Kyu;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.18 no.5
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    • pp.450-461
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    • 1998
  • The optimal reheating conditions to apply the thixoforging and semi-solid die casting process were investigated by changing the reheating time, the holding time, the reheating temperatures, the capacity of the induction heating system, and the adiabatic material size. In the case of solid fraction fs=50% (for semi-solid die casting), the microstructure of SSM (specimen size:$d76{\times}l90$) at the condition of the first elevating time of 4 min, holding time of 1 min and holding temperature of $350^{\circ}C$, the second elevating time of 3 min, holding time of 3 min and holding temperature of $575^{\circ}C$, the third elevating time of 1 min, holding time of 2 min and holding temperature of $584^{\circ}C$, capacity of Q=8.398KW is obtained with globular microstructure and finest. In addition, in the case of solid fraction fs=55% (for thixoforging), the SSM (specimen size:$d76{\times}l90$) at the condition of the first elevating time of 4 min, holding time of 1 min and holding temperature of $350^{\circ}C$, the second elevating time of 3 min, holding time of 3 min and holding temperature of $570^{\circ}C$, the third elevating time of 1 min, holding time of 2 min and holding temperature of $576^{\circ}C$, capacity of Q=12.04KW is obtained with the finest globular microstructure. We saw that the most important factor in a three-step reheating process is the final holding time.

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A-8 Three -Dimensional Crystalizing Combined $\pi$-Bonding Orbitals ("O" S' Bonding) And Electrical And Mechanical Properties of Alloy Metals

  • Oh, Hung-Kuk
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1995.03a
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    • pp.90-106
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    • 1995
  • The "O"S' BONDING make metallic and non-metalic crystal structures and form localized superconducting orbitals , which induce electrical conduction , semi-conduction, and superconduction. The orbitals are proced by Ampere's law, Faraday's law , Meissner effect, highcritical temperature of thecopper oxide layers. abnomal trans-membrane signal in cancer cell and plastic deformations bytwins and dislocations, In the case of alloying metals, the most deterimentla cases of electrical conduction are those of solid solution and intermetalic compound . The highest case for the hardness are also those of solid solution and intermetallic compound. It explains the contributions of the "O"S' BONDING for conduction bands and plastic deformation by twins and dislocations.ns and dislocations.

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Effect of the Casting Conditions on the Globulization of Primary Al of $AlSi_7Mg$ Alloy (($AlSi_7Mg$알루미늄 합금의 초정 구형화에 대한 주조조건의 영향)

  • Han, Yo-Sub;Lee, Ho-In;Lee, Jae-Chul
    • Journal of Korea Foundry Society
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    • v.23 no.1
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    • pp.40-46
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    • 2003
  • Semisolid forming requires alloys with non-dendritic microstructure of the thixotropy. Recently, low pouring temperture method without stirring, i.e. liquidus casting has been found out new fabrication method of the semisolid metals. Effects of melt superheat and mold conditions on the globulization of primary Al of $AlSi_7Mg$ alloy were investigated in gravity casting process without stirring. The microstructures of primary Al as function of melt superheat and mold temperature show globular, rosette and dendritic shapes. The conditions for globular microstructure of primary Al were low melt superheat < 35 K and low mold temperature < 500 K. The thermal conditions for globular microstructure of primary Al were undercooled melt at early solidification stages and slow cooling < 0.6 K/s. It was found that the initial microstructure was maintained throughout the solidification and the globules of primary Al can be obtained by high nucleation of fine and spherical nuclei due to enhanced undercooling of melt.

The Study on the Microstructures in Direct Squeeze cast and Gravity Cast of 7XXX Al Wrought Alloy (중력주조 및 직접가압주조 7XXX계 Al합금의 미세조직에 관한 연구)

  • Kim, Sug-Won;Kim, Dae-Young;Woo, Ki-Do;Kim, Dong-Kun
    • Journal of Korea Foundry Society
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    • v.19 no.1
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    • pp.47-53
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    • 1999
  • Squeeze casting process has been used in the field of a commercial manufacturing method, in which metal is enforcedly solidified under pressure enough to prevent the cast defects such as either gas porosity or shrinkage defect. In this paper, to clarify the relationship between applied pressures and macro ${\cdot}$ microstructural behaviors in gravity and direct squeeze casts, specimens were cast by various squeezing pressures during solidification of 7000 series Al wrought alloy in the metal die designed specially. The applied pressures used in this study were 0, 25, 50, and 75 MPa. The microstructural morphologies of squeeze cast were more fine and dense with increasing the applied pressures, because of the greater solidification rate of billet resulting from the applied pressure. A normal segregation phenomenon of an increasing in amount of eutectics towards the center of the billet was observed for squeeze casts, whereas gravity cast showed an inverse segregation phenomenon of an increasing in amount of eutectics towards the edge in the billet. This change in segregation pattern which is normal or inverse is due to a higher radial temperature gradient and reduced time in the semi solid state for squeeze casting.

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Optimization of Induction Coil Design for Reheating in Thixoforming Process (Thixoforming을 위한 재가열용 유도코일 설계의 최적화)

  • 김남석
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.165-168
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    • 1999
  • The coil design of induction heating systems and their optimization are of paramount importance for semi-solid processing(SSP) The authors of this paper present the coil design and optimization of a 60 Hz induction heating system for ALTHIX 86S (Al-6%_Si-3%Cu-0.3%Mg) alloy. An objective function on the basis of the optimization process for the coil design is proposed by introducing an optimization technique. Finally the results of the optimal coil design are also applied to the induction heating process to obtain a fine globular microstructure. The proposed new objective function based on the computational techniques would contribute to obtaining the thixoformed components with good mechanical properties and reducing lead time.

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A Study on Rheology Forming Process of Al-7%Si Alloy with Electromagnetic Application (전자교반을 응용한 Al-7%Si 알루미늄 소재의 레올로지 성형공정에 관한 연구)

  • Ko J.H.;Seo P.K.;Kang C.G.
    • Transactions of Materials Processing
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    • v.15 no.3 s.84
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    • pp.195-205
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    • 2006
  • This paper focuses on a rheo-forming of am part fabricated by electromagnetic stirring system (EMS). This forming process take place under high pressure of high pressure die casting and thin walled casting is possible. Furthermore, the productivity is better than low pressure die casting because of shorter cycle time. The advantages of rheo-forming are performed in the semi solid state with laminar flow and the gas content is low, which makes welding possible. Therefore this research applies for arm part with EMS and has investigated the mechanical properties after T6 and T5 heat-treatment.

The effect of the size of the Si on mechanical properties of large suspension part in thixoforming process (Thixoforming 공정에서 Si의 크기가 대형 suspension 부품의 기계적 성질에 미치는 영향)

  • 신현기;서판기;박계주;강충길
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.808-811
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    • 2002
  • In thixoforming process, the size of Si particles is changed by many parameters of forming. Especially, reheating and heat treatment are very important parameters. It was found that the mechanical properties was significantly improved by the thixoforming process. In this study, to investigate the relation between the mechanical properties and Si particles, the experiment of semi-solid die casting has been performed. Large suspension part with A356 alloy was fabricated with controlled ram speed. The effect of the size and shape of silicon particles on microstructure of tensile test has been investigated.

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Development Trend of Magnesium Casting Technology (마그네슘 주조성형기술의 개발동향)

  • Kim, Hyun-Sik;Ye, Dea-Hee;Kang, Min-Cheol
    • Journal of Korea Foundry Society
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    • v.31 no.5
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    • pp.243-248
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    • 2011
  • Magnesium alloys have many advantages such as light-weight, high machinability, damping capacity, etc. So magnesium alloy parts have been used in transportation, mobile phone, military industries. Because of HCP atomic structure, Magnesium is very difficult in plastic deformation process, so most of magnesium products are fabricated by casting process. Magnesium alloys have low heat-capacity, high fluidity and low Fe solubility. For these reasons it is more suitable than aluminum in mass-production by casting. And various casting technologies have been developed. So casting technologies for magnesium developed recently is discussed in this paper.

Microstructure and Mechanical Property of A356 for Rheocasting Using 6-Pole Electromagnetic Stirring Casting Process (6극 전자석 전자교반 레오캐스팅에 따른 A356의 조직적 / 기계적 영향분석)

  • Kim, Baek-Gyu;Roh, Jung-Suk;Bang, Hee-Jae;Heo, Min;Park, Jin-Ha;Jeon, Chung-Hwan
    • Journal of Korea Foundry Society
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    • v.40 no.3
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    • pp.61-65
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    • 2020
  • Rheo-diecasting with stirring has been used in many material industries. As the 4th Industrial Revolution approaches the world, eco-friendly high-strength and light-weight materials become more important. Casting methods have been studied and used for aluminum-alloy automobile parts. This study carried out the effect analysis of the micro-structure and mechanical properties, such as yield/ultimate tensile strength, elongation, and hardness, of A356 using the 6-pole EMS (electro-magnetic stirring) casting process with a high electromagnetic force. As a result, the hardness and elongation of the A356 after T6 heat-treatment show a significant improvement, respectively, by 20% and 50%.

A Study on the Inner Temperature Behaviors in the Casting Process for the Development of the Automatic Parts (자동차 부품 소재 개발에 따른 캐스팅 과정의 부품 내부온도 거동에 관한 연구)

  • Cha Young-Hoon;Sung Back-Sub;Jang Hoon;Kim Mi-Ai;Kim Jung-Dae;Kim Sun-Jun;Kim Duck-Joong;Lee Youn-Sin
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.279-284
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    • 2005
  • The casting defects that are caused by molten metal were cold shut formation, entrapment of air, gas, and inclusion. But the control of casting defects has been based on the experience of the foundry engineers. In this thesis, the computer simulation analyzed the flow of molten metal. The quantitative analyses which proposed the effective mold design was executed Flow patterns of 0.15-0.16m/s molten metal in 15 mm thin plate casting were investigated in order to optimize die-casting process. As increasing ingate velocity in thin plate casting, cold shot was decreased. The parameters of runner shape that affected on the optimized conditions that was calculated with simple equation were investigated. These die casting process control techniques of automobile valve body mid-plate have achieved good agreement with the experimental data of tensile strength, hardness test, and material structure photographies satisfactory results.

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