• 소성∙가공
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• 제3권1호
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• pp.3-17
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• 1994

The semi-solid metal forming for vigorously agitated semi-solid alloys has been widely studied over the last decade. Metal forming processes are now being developed using alloys in the semi-solid state, among them are rolling, forging, extrusion, and die casting. Some of these are now employed commercially to produce a components and are also used to fabricate metal matrix composites. The semi-solid materials can be processed either directly during solidification and for this purpose mechanical stirring was demonstrated to produce a highly solidification. This paper is concerned with the influence of processing parameters on limitations of semi-solid forming.

• 소성∙가공
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• 제7권4호
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• pp.364-374
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• 1998

It is the objective of this study to analyze the effect of various process variables on the quality of extruded product and extrusion force for semi-solid extrusion of Al2024 with solid phase structure of globular type by the finite element method. Process variables are initial solid fraction, ram speed, semi-angle of die, and reduction in area. The results of experiment are compared with those of simulation in order to verify the usefulness of the developed finite element program. The flow and deformation of semi-solid alloy are analyzed by coupling by coupling the deformation of porous skeleton and the flow of liquid phase. It is also assumed that initial solid fraction is homogeneous.

• 소성∙가공
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• 제6권3호
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• pp.239-249
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• 1997

The behaviour of alloys in the semi-solid state strongly depends on the imposed stress state and on the morphology of the phase which can vary from dendritic to globular. To optimal net shape forging of semi-solid materials, it is important to investigate for filling phenomena in forging process of arbitrarily shaped dies. To produce a automotive part which has good mechanical property, the filling pattern according to die velocity and solid fraction distribution has to be estimated for arbitrarily shaped dies. Therefore, the estimation of filling characteristic in the forging simulation with arbitrarily shaped dies of semi-solid materials are calculated by finite element method with proposed algorithm. The proposed theoretical model and a various boundary conditions for arbitrarily shaped dies is investigated with the coupling calculation between the liquid phase flow and the solid phase deformation. The simulation process with arbitrarily shaped dies is performed to the isothermal conditions of two dimensional problems. To analysis of forging process by using semi-solid materials, a new stress-strain relationship is described, and forging analysis is performed by viscoelastic model for the solid phase and the Darcy's law for the liquid flow. The calculated results for forging force and filling limitations will be compared to experimental data. The filling simulation of simple products performed with the uniform billet temperature(584$^{\circ}C$) from the induction heating by the commercial package MAGMAsoft. The initial step of computation is the touching of semi-solid material with the end of die gate and the initial concept of proposed system just fit with the capability of MAGMAsoft.

• 한국정밀공학회지
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• 제14권8호
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• pp.82-91
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• 1997

The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 춘계학술대회논문집
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• pp.56-62
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• 2000

Semi-solid forming process has some advantages such as successful manufacturing of high quality components with less inner defects suitable for less machining high productivity and energy-saving effect. the thixotropic behavior(solid-like in the unperturbed state and liquid-like during shearing) has been the basis for the semi-solid forming process. The main focus of this article is the investigation of the effect of T6 heat treatment and alloying elements on the mechanical properties in the semi-solid formed products using thixotropic hypoeutectic (A357 and ALTHIX 86S) and hypereutectic(A390) materials. The new methods to produce semi-solid formed components with high quality are also proposed and discussed in terms of a die design and the development of a lubricant.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.131-134
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• 2007

A semi-solid forming technology has a lot of advantages compared to the die casting, squeeze casting and hot/cold forging, so semi-solid forming has been studied actively. Semi-solid forming has two methods. One is thixoforming with reheating of prepared billet, the other is rheoforming with cooled melt until semi-solid state. Thixoforging technology can produce non-dendritic alloys for semi-solid forming complex shaped parts in metal alloys. In this study, the thixoforging was experimented with made rheology materials by the spiral stirrer equipment. Rheology materials for forging were made by A356 casting aluminum alloy and A6061 wrought aluminum alloy. After experiment, forged samples were measured microstructure and were heat treated for high mechanical properties.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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• pp.135-147
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• 1997

The production of light metal parts using aluminum is mainly performed by die casting and squeeze casting, which directly fabricate the required shape from the liquid state. However, die casting is subject to defects such as shrinkage porosity and air trapped when molten metal enters the cavity, whilst squeeze casting also has defects due to turbulent flow in the die cavity. Both diecasting and sqeeze casting have inhomogeneous mechanical property in terms of dendritic structure during solidification. Active research has been carried out on semi-solid processing, rather than on conventional process methods such as die casting, which involve various problems. Therefore in this paper, to introduce the fundamental technology for d e design, in die casting and forging process with semi-solid materials, relationship between stress and strain of semi-solid materials, and for producing parts die design has been proposed as parameters of globulization of the microstructure and gate shape. The prevention of various defects to produce sound parts are also introduced.

• 대한기계학회논문집
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• 제14권3호
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• pp.581-593
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• 1990

본 연구에서는 교반기술에 의하여 얻어진 반응고상태의 금속에 단섬유를 첨가 하여 복합재료를 제조하였다. 그리고 제조되어진 복합재료에 있어서 섬유의 분산상 태및 기지재와의 접합관계를 조사하여 압연가공에 필요한 반응고상태인 금속복합재료 의 제조방법을 확립하였다. 균일하게 분실되어진 반용융상태의 단섬유강화형 금속복 합재료를 직접 압연하여 박판을 제조할 수 있는 가능성을 검토하였으며, 또한 제조되 어진 박판의 인장시험에 의하여 기계적 성질을 조사하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.831-832
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• 2006

Solid-state processing via the bulk mechanical alloying enables us to directly fabricate $Mg_2X$ semi-conductive material performs. Precise control of chemical composition leads to investigation on the dilution and enrichment of X in $Mg_2X$. Two types of solid-state reactivity are introduced: e.g. synthesis of $Mg_2Si$ from elemental mixture Mg-Si is nucleation-controlled process while synthesis of $Mg_2Sn$ from Mg-Sn, diffusion-controlled process. Thermoelectricity of these $Mg_2X$ is evaluated for discussion on the validity and effectiveness of this new PM route as a reliable tool for fabrication of thermoelectric compounds.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.120-123
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• 2001

The semi-solid casting will have a higher internal integrity, mechanical properties and dimensional accuracy than the conventional castings. This process can reduce the manufacturing costs and finished weight for critical components. The semi-solid casting are capable of greater dimensional repeatbility, this supplies considerable savings when extensive machining, salvage and scrap are key variables in the current automotive product. One of the most important factor regarding the semi-solid die casting process are the reheating method of the raw materials to the semi-solid state. Therefore, in this present work, the horizontal type induction heating system to obtain the optimal reheating conditions suitable for semi-solid die casting process was designed and manufactured. And the microstructure of reheated materials was investigated.