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Journal of Materials Science & Technology 2007年第6期23卷 342-346页

作者： Wen LIU Shuming XING Peiwei BAO Milan ZHANG Liming XIAO Beijing Jiaotong University Beijing 100044 China

The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.

关键词： semi-solid metal Energy dissipation Rheology Apparent viscosity Model

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Insights into the rheological modeling of semi-solid metals:Theoretical and simulation study

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Journal of Materials Science & Technology 2022年第5期100卷 182-192页

作者： Zhen Ma Huarui Zhang Hanwei Fu Yanzhao Yang Jianji Wang Ming Du Hu Zhang School of Materials Science and Engineering Beihang UniversityBeijing 100191China FAW-VOLKSWAGEN Automobile Co. LtdQingdao 266000China Ningbo Institute of Technology Beihang UniversityNingbo 315832China

The power law model is the most widely used model for the rheological behavior of semi-solid metals(SSMs)in the numerical simulation of semi-solid ***,it is still not known why the anomalous negative flow exponent exists in the power law model for SSMs and its influence on the *** this research,the rheological behavior of semi-solid Al-7Si-0.3Mg aluminum alloy is experimentally studied followed by *** power law model fitting results show flow curves deviate from the experimental data and negative flow exponents,which are physically nonsensical and inapplicable to the simulation of SSMs flow proved by hydrodynamic *** drawback of the power law model stems from neglecting the yield stress of *** contrast,the model referring Herschel-Bulkley(HB)theory which takes yield stress into consideration has reasonable flow exponent and yields good agreement between the fitting and experimental ***,the simulation of die filling process is conducted,suggesting that the power law model over-optimistically predicts the tendency of blistering and misrun defects at low temperature and high filling velocity during semi-solid processing.

关键词： semi-solid metal Rheological behavior Modeling Simulation Aluminum alloys

Development of aluminum rheo-extrusion process using semi-solid slurry at low solid fraction

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1763-1768页

作者： T.RATTANOCHAIKUL S.JANUDOM N.MEMONGKOL J.WANNASIN Department of Mining and Materials Engineering Faculty of EngineeringPrince of Songkla University Department of Industrial Engineering Faculty of EngineeringPrince of Songkla University

An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery. The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions. A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 ram. The semi-solid metal process used in this study was the gas induced semi-solid （GISS） technique. To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fi-action on the extrudability, microstructure, and mechanical properties of extruded samples were investigated. The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.

关键词： aluminum alloys extrusion semi-solid metal rheo-extrusion gas induced semi-solid (GISS)

Rheological characterization of A201 aluminum alloy

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1638-1642页

作者： A.BLANCO Z.AZPILGAIN J.LOZ ARES P.KAPRANOS I.HURTADO Mechanical and Manufacturing Department Faculty of EngineeringMondragon Unibertsitatea

The thermodynamic characterization as well as the rheological characterization of the A201 alloy were *** simulations (CALPHAD method) and calorimetric experiments were performed to determine the solidus and liquidus temperatures, the melting range and the sensitivity of the solid fraction at the thixoforming *** rheology of aluminium alloy A201 was examined using a high temperature Searle *** flow behaviour was analyzed with concentric cylinders of graphite to avoid chemical interactions with the liquid or semi-solid *** rotational body was grooved to prevent a phenomenon called wall *** cooling experiment was used to observe the shear rate effects on the flow *** can be seen that the viscosity level decreases at higher shear *** rate jump experiment was carried out to evaluate the steady state flow curve within the analyzed shear rate range from 60 s-1 to 260 *** is found that the power law indexes are-1.35 and-1.49 for 35% and 45% solid fraction, ***, some mechanical property data of as-cast and as-thixoformed A201 alloy are included indicating the potential for high strength applications.

关键词： aluminum alloys rheology mechanical properties semi-solid metal tixotropy shear-thinning

Coarsening rate of microstructure in semi-solid aluminium alloys

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1672-1676页

作者： H.V.ATKINSON D.LIU Mechanics of Materials Research Group Department of EngineeringUniversity of LeicesterUniversity Rd. Now with Wolfson Microelectronics PLC.

The rate of microstructural coarsening of recrystallisation and partial melting (RAP) and cooling slope (CS) processed materials in the semi-solid state is compared with rates found in the *** rate of coarsening depended on the liquid fraction but RAP route 2014 alloy with 37% liquid coarsened slightly more slowly than the CS route 2014 alloy with a lower liquid fraction of 17%, contrary to *** the CS route, an increase in liquid fraction resulted in faster coarsening.A modified 2014 alloy with Fe, Mn and Zn stripped out of the composition gave a relatively high coarsening *** coarsening rate was also relatively high for CS 201 alloy in comparison with either RAP 2014 or CS *** coarsening rates are thought to be associated with the presence of particles which inhibit the migration of liquid film grain *** could be the result of pinning or of the liquid film impeding diffusion at the boundary.

关键词： coarsening semi-solid metal 2014 alloy recrystallisation and partial melting cooling slope

Analysis of semi-solid response under rapid compression tests using multi-scale modelling and experiments

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1691-1695页

作者： V.FAVIER H.ATKINSON Arts et Métiers ParisTech CNRS PIMM151 Boulevard de l'Hpital Department of Engineering University of Leic esterUniversity Road

Simulating semi-solid metal forming requires modelling semi-solid ***, such modelling is difficult because semi-solid behavior is thixotropic and depends on the liquid-solid spatial distribution within the *** order to better understand and model relationships between microstructure and behavior, a model based on micromechanical approaches and homogenisation techniques is *** model is an extension of a previous model established in a pure viscoplastic framework to account for ***, experimental load-displacement signals reveal the presence of an elastic-type response in the earlier stages of deformation when semi-solids are loaded under rapid *** elastic feature of the behaviour is attributed to the response of the porous solid skeleton saturated by incompressible liquid.A good quantitative agreement is found between the elastic-viscoplastic predicted response and the experimental *** precisely, the strong initial rising part of the load-displacement curve, the peak load and the subsequent fall in load are well *** effect of solid fraction on mechanical response is in qualitative agreement with experiments.

关键词： semi-solid metal aluminium solid fraction elastic-viscoplasticity homogenization

Continuous Extruding Extending Forming of semi-solid A2017 Alloy

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Journal of Wuhan University of Technology(Materials Science) 2006年第1期21卷 76-79页

作者：王顺成 School of Materials and metallurgy Northeastern University Shenyang 110004 China

Continuous extruding/ extending formiug process for A2017 alloy in semi-solid state was proposed through installing extending die at the outlet of shearing- cooling- rolling （SCR） machine. A series of experiments to produce fiat bar of A2017 alloy were carried oat. The forming process, metal flow behavior in die and microstructure and mechanical property of prodacts were investigated. It is shown that if the pouring temperature of melt was higher, the die was filled with semi-solid slurry with low solid fraction and periodical cracks would occur on the product surface ; If its pouring temperature was lower or the preheating temperature of die was lower, semisolid slurry would solidify rapidly and block the die after entering the cavity. The analysis of mass flow trace shows that the semi-solid slurry move forward layer by layer and fills the die extending cavity in radiation manner and the velocity of mass flow in the central area of extending cavity and exit of mould is the maximum, and then decreases gradually from the center to both sides of die wall. By inereasiug the die extending angle, the velocity of mass flow becomes more homogeneous. Under rational process control and die design, the A2017 fiat bar with transverse section of 10 × 50 mm and with good surface and fine equiaxed grains can be obtained by continuous extruding/extending forming process. The product＇s tensile strength and elongation are 420.5 MPa and 14.2% , respectively.

关键词： semi-solid metal extruding/ extending formung metal flow behavior A2017 alloy microstructure property

Microstructural evolution during semisolid state strain induced melt activation process of aluminum 7075 alloy

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1663-1671页

作者： A．BOLOURI M．SHAHMIRI E．N．H．CHESHMEH Department of Mechanical Engineering Eastern Mediterranean University Mersin 10 Turkey School of Material Engineering and metallurgy Iran University of Science and Technology Tehran 16844 Iran

The effects of compression ratio on the microstructure evolution of semisolid 7075 Al alloy produced by the strain induced melt activation （SIMA） process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments were carried out at 625 ℃ for predetermined time intervals. The results reveal that the average grain size is gradually reduced with the increase of the compression ratio. When the compression ratio surpasses 30%, the above descending trend is not as evident as that below 30% reduction. During the subsequent heat treatments, the recrystallization is induced in the deformed samples by the increasingly accumulated strain energy. The grain growth mechanisms and the microstructural coarsening of the SIMA processed 7075 Al alloy were discussed and confirmed.

关键词： thixoforming thermomechanical processing aluminium alloys semi-solid metal

Microstructure and mechanical properties of A356 aluminum alloy wheels prepared by thixo-forging combined with a low superheat casting process

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Transactions of Nonferrous metals Society of China 2014年第7期24卷 2214-2219页

作者：王顺成周楠戚文军郑开宏广东省工业技术研究院(广州有色金属研究院)金属加工与成型技术研究所广州510650

The A356 aluminum alloy wheels were prepared by thixo-forging combined with a low superheat casting process. The as-cast microstructure, microstructure evolution during reheating and the mechanical properties of the thixo-forged A356 aluminum alloy wheels were investigated. The results show that the A356 aluminum alloy billet with fine, uniform and non-dendritic grains can be obtained when the melt is cast at 635 ℃. When the billet is reheated at 600 ℃ for 60 min, the non-dendritic grains are changed into spherical ones and the billet can be easily thixo-forged into wheels. The tensile strength and elongation of thixo-forged wheels with T6 heat treatment are 327.6 MPa and 7.8%, respectively, which are higher than those of a cast wheel. It is suggested that the thixo-forging combined with the low superheat casting process is an effective technique to produce aluminum alloy wheels with high mechanical properties.

关键词： aluminum alloy wheel semi-solid metal thixo-forging low-superheat casting