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Energy Dissipation and Apparent Viscosity of Semi-solid Metal during Rheological Processes PartⅡ:Apparent Viscosity 被引量:1
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作者 Wen LIU Shuming XING Peiwei BAO Milan ZHANG Liming XIAO 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2007年第6期801-805,共5页
This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry prepar... This study investigated the rheological properties of semi-solid metal. An analytical model of apparent viscosity was built up based on analysis of energy dissipation during rheological processes such as slurry preparing, delivering and model filling. The rheological properties of SSM (semi-solid metal) slurry was described by an analytical model in terms of microstructural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuant velocity and relative velocity between liquid and solid phase. The model was verified in the experiment of A356 alloys with a coaxial double-bucket rheometer. And the maximum relative error between the theoretical value and measured one is less than 20%. The results of experiment and theoretical calculation also indicate that the microstructural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuant velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological properties. 展开更多
关键词 semi-solid metal Apparent viscosity Energy dissipation RHEOLOGY MODEL
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Energy Dissipation and Apparent Viscosity of Semi-solid Metal during Rheological Processes PartⅠ: Energy Dissipation 被引量:1
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作者 Wen LIU Shuming XING Peiwei BAO Milan ZHANG Liming XIAO 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2007年第3期342-346,共5页
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 ... 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. 展开更多
关键词 semi-solid metal Energy dissipation RHEOLOGY Apparent viscosity MODEL
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Influence of surface liquid segregation on corrosion behavior of semi-solid metal high pressure die cast aluminium alloys
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作者 E.P.MASUKU H.MLLER +1 位作者 U.A.CURLE P.C.PISTORIUS 《中国有色金属学会会刊:英文版》 CSCD 2010年第S3期837-841,共5页
The corrosion behavior(in chloride medium) of the surface layer of SSM-HPDC plates of alloys 7075-T6 and 2024-T6 was compared with that of the wrought alloys 7075-T6 and 2024-T6.Potentiodynamic testing was performed i... The corrosion behavior(in chloride medium) of the surface layer of SSM-HPDC plates of alloys 7075-T6 and 2024-T6 was compared with that of the wrought alloys 7075-T6 and 2024-T6.Potentiodynamic testing was performed in deaerated 3.5%NaCl solution.In separate tests,the open-circuit potential was monitored in aerated 3.5% NaCl for 30 min after immersion.The electrochemical tests show that there is no significant difference in the pitting potential of the wrought alloys and that of the Cu-enriched surfaces of the SSM-HPDC alloys. 展开更多
关键词 semi-solid metal(SSM) forming WROUGHT aluminium alloys ALLOY 7075 ALLOY 2024 corrosion surface liquid SEGREGATION
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Formation and Evolution of Non-dendritic Microstructures of Semisolid Alloys Prepared by Shearing/Cooling Roll Process 被引量:13
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作者 Shuncheng WANG Furong CAO Renguo GUAN Jinglin WEN 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2006年第2期195-199,共5页
The shearing/cooling roll (SCR) process was adopted to prepare semi-solid A2017 alloy. The formation and evolution of non-dendritic microstructures in semi-solid A2017 alloy were studied. It is shown that the micros... The shearing/cooling roll (SCR) process was adopted to prepare semi-solid A2017 alloy. The formation and evolution of non-dendritic microstructures in semi-solid A2017 alloy were studied. It is shown that the microstructures of semi-solid billets transform from coarse dendrites into fine equiaxed grains as the pouring temperature of molten alloy decreases o.r roll-shoe cavity height is reduced. From the inlet to the exit of roll-shoe cavity, microstructure of semi-solid slurry near the shoe surface is in the order of coarse dendrites, degenerated dendrites or equiaxed grains, but fine equiaxed grains are near the roll surface. Microstructural evolution of semi-solid slurry prepared by SCR process is that the molten alloy nucleates and grows into dendrite firstly on the roll and shoe's surface. Under the shearing and stirring given by the rotating roll, the dendrites crush off and disperse into the melt. Under the shearing and stirring on semi-solid slurry with high volume fraction of solid, the dendrite arms fracture and form equiaxed grain microstructures. 展开更多
关键词 semi-solid metal processing Non-dendrite Microstructural evolution Shearing and stirring Aluminum alloy
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Preparation of semi-solid slurry containing fine and globular particles for wrought aluminum alloy 2024 被引量:13
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作者 郭洪民 杨湘杰 《中国有色金属学会会刊:英文版》 EI CSCD 2007年第4期799-804,共6页
The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouring with shearing field(LSPSF). The appreciate combination of pouring temperature and rotati... The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouring with shearing field(LSPSF). The appreciate combination of pouring temperature and rotation speed of barrel, can give rise to a transition of the growth morphology of primary α(Al) from coarse-dendritic to coarse-particle-like and further to fine-globular. The combined effects of both localized rapid cooling and vigorous mixing during the initial stage of solidification can enhance wall nucleation and nuclei survival, which leads to the formation of fine-globular primary α(Al). By using semi-solid slurry prepared by LSPSF, direct squeeze cast cup-shaped component with improved mechanical properties such as yield strength of 198 MPa, ultimate tensile strength of 306 MPa and elongation of 10.4%, can be obtained. 展开更多
关键词 锻造铝合金 半固体金属加工 凝固 微观结构 机械性能
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Industrial development of gas induced semi-solid process 被引量:10
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作者 S.THANABUMRUNGKUL S.JANUDOM +2 位作者 R.BURAPA P.DULYAPRAPHANT J.WANNASIN 《中国有色金属学会会刊:英文版》 CSCD 2010年第S3期1016-1021,共6页
The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting indust... The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting. 展开更多
关键词 GAS induced semi-solid(GISS) RHEOCASTING DIE CASTING semi-solid metal INDUSTRIAL applications
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Microstructure evolution of semi-solid 2024 alloy during two-step reheating process 被引量:6
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作者 王顺成 李元元 +1 位作者 陈维平 郑小平 《中国有色金属学会会刊:英文版》 EI CSCD 2008年第4期784-788,共5页
A two-step reheating process was proposed and applied to perform reheating experiments on the semi-solid 2024 alloy billet. In this process, the semi-solid billet was firstly heated over liquidus temperature and then ... A two-step reheating process was proposed and applied to perform reheating experiments on the semi-solid 2024 alloy billet. In this process, the semi-solid billet was firstly heated over liquidus temperature and then isothermally held at solid-liquid zone temperature. Microstructure evolution of the semi-solid billet during two-step reheating was studied by optical microscope and compared with that during isothermal reheating. The results show that the remelting rate of the semi-solid billet during two-step reheating is faster than that during isothermal reheating. Under the same reheating time, the grains of the semi-solid billet reheated by two-step reheating process are finer and rounder than those by isothermal reheating process. The present experimental results indicate that accelerating the formation of liquid phase during the two-step reheating process can restrain the coalescence of grains to a certain extent, and thus refine the grain size and promote the grain spheroidization. 展开更多
关键词 半固态金属 2024合金 微观结构 两步加热过程
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Effect of original microstructures on microstructural evolution of A2017 semi-solid alloy billets during reheating 被引量:2
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作者 王顺成 曹富荣 温景林 《中国有色金属学会会刊:英文版》 CSCD 2005年第3期577-582,共6页
The microstructural evolution of the A2017 semi-solid alloy billets provided with rheocasting and extruding/extending forming by shearing-cooling-rolling(SCR) technology during reheating in semi-solid state was invest... The microstructural evolution of the A2017 semi-solid alloy billets provided with rheocasting and extruding/extending forming by shearing-cooling-rolling(SCR) technology during reheating in semi-solid state was investigated. The microstructural differences and their generation causes for both billets were also analyzed. The results show that during reheating, the grains of rheocasting billets grow up and spheroidize gradually with the prolongation of isothermal holding time, the eutectic liquid phase at low melting point forms mainly among the grains. However, the grains of the extruding/extending forming billets grow up abnormally through grain coalescence in the initial stage of the reheating, the entrapment of large amount of liquid within grains occurs, and the grain sizes in the reheating billets are coarse and inhomogeneous. Compared with extruding/extending forming billets, rheocasting billets have smaller and uniform grains in reheating microstructure and can rapidly form liquid phase among grains. Therefore, rheocasting billets are more suitable for the semi-solid forming than the extruding/extending forming billets. 展开更多
关键词 铝合金 半固态合金 延展成型 微结构演化 流变铸造
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Effects of processing parameters on microstructure of semi-solid magnesium alloy
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作者 Shusen WU Dongnan LI +2 位作者 Youwu MAO Zehui XIAO Jirong LUO 《China Foundry》 SCIE CAS 2004年第1期45-48,共4页
In this paper, the effects of pouring temperature of magnesium melt, preheating temperature of the barrel of the screw mixer, and shear rate on the solidified microstructures of semi-solid slurry were investigated by ... In this paper, the effects of pouring temperature of magnesium melt, preheating temperature of the barrel of the screw mixer, and shear rate on the solidified microstructures of semi-solid slurry were investigated by a mechanical stirring semi-solid process. The appropriate processing parameters of slurry preparation were obtained, and the mold filling ability of semi-solid slurry for thin-walled casting was examined. Results indicate that the solid volume fraction of non-dendritic microstructure increases with a decrease in pouring temperature of magnesium melt and the barrel preheating temperature of the screw mixer. Also the grain size of primary α-phase is reduced. Furthermore, the solid volume fraction of semi-solid nondendritic structure decreases with an increase of shear rate. The fine and round granular microstructure with 30~50 μm in size of semi-solid AZ91D magnesium alloy was presented. Finally, a 1.0 mm thin-walled casting with a clear contour and good soundness was successfully made by semi-solid rheo-diecasting. 展开更多
关键词 semi-solid metal MAGNESIUM alloy RHEOCASTING SLURRY MICROSTRUCTURE
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Continuous Extruding Extending Forming of Semi-solid A2017 Alloy
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作者 王顺成 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2006年第1期76-79,共4页
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... 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. 展开更多
关键词 semi-solid metal extruding/ extending formung metal flow behavior A2017 alloy MICROSTRUCTURE PROPERTY
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金属半固态浆料非枝晶微观组织形成机制与表征
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作者 徐升亮 郭洪民 杨湘杰 《精密成形工程》 北大核心 2024年第7期109-123,共15页
半固态技术自20世纪70年代由麻省理工学院开发以来,因其独特的优势而在全球范围内得到了广泛的研究。非枝晶组织的形成机理是半固态成形技术的基石,它决定了在特定条件下应采用哪些工艺来获得优质的半固态组织,对开发新工艺具有重要的... 半固态技术自20世纪70年代由麻省理工学院开发以来,因其独特的优势而在全球范围内得到了广泛的研究。非枝晶组织的形成机理是半固态成形技术的基石,它决定了在特定条件下应采用哪些工艺来获得优质的半固态组织,对开发新工艺具有重要的指导作用。经过近半个世纪的发展,半固态浆料制备过程中非枝晶结构的形成机理已经发展出许多不同的观点。由此衍生了丰富的半固态浆料制备技术,大大促进了半固态领域的发展。为了进一步理解凝固过程中球晶的形成机制,对各种非枝晶组织的形成机制进行了梳理,基于制备原理将半固态制浆技术分为搅拌制备技术类和低过热度制备技术类,并对常见的几种技术的原理和应用进行了总结。半固态产品的性能在很大程度上取决于其微观组织结构,但半固态形态复杂,传统的二维表征手段对材料内部空间结构的理解可能存在误差。对半固态浆料的二维微观组织和三维显微组织表征技术进行总结分析,为理解金属半固态浆料的微观结构演变和微观组织与性能之间的关系提供了理论基础。 展开更多
关键词 金属半固态浆料 非枝晶组织 形成机制 组织表征 浆料制备 三维重构
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半固态等温热处理对Zr基非晶复合材料塑性变形机制的影响
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作者 杨湘杰 杨颜 +2 位作者 刘军 史坤 郑彬 《材料导报》 EI CAS CSCD 北大核心 2023年第4期159-165,共7页
通过添加不同体积分数的Nb,本工作设计了一系列Zr基非晶复合材料,主要研究了Nb含量对铸态、半固态非晶复合材料的微观组织及塑性性能的影响。结果表明:非晶复合材料塑性应变量随晶体相(β-Zr相)体积分数增加而呈现S型增强规律。半固态... 通过添加不同体积分数的Nb,本工作设计了一系列Zr基非晶复合材料,主要研究了Nb含量对铸态、半固态非晶复合材料的微观组织及塑性性能的影响。结果表明:非晶复合材料塑性应变量随晶体相(β-Zr相)体积分数增加而呈现S型增强规律。半固态等温处理后的非晶复合材料塑性提升,但其塑性增长率随Nb含量增加而减小。当D C(当量直径)/X(平均自由程间距)≥0.65时,β-Zr相体积分数出现最小临界阈值35%,此时材料塑性开始迅速提升;D C/X≥1.5时,β-Zr相体积分数超过54%后,材料塑性保持稳定,进一步说明非晶复合材料塑性与β-Zr相体积分数有关。 展开更多
关键词 块体非晶复合材料 半固态等温热处理 微观结构 剪切带
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半固态浆制备技术的新进展 被引量:68
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作者 崔建忠 路贵民 +1 位作者 刘丹 董杰 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2000年第4期110-113,共4页
制浆是半固态金属加工的关键环节 .论述了半固态金属浆制备技术的发展与现状 ,提出了制浆新工艺———液相线铸造 .通过对 2 61 8及 70 75铝合金的实验研究表明 ,采用液相线铸造法可以获得均匀、细小的非枝晶 ,其晶粒尺寸小于 50 μm ,... 制浆是半固态金属加工的关键环节 .论述了半固态金属浆制备技术的发展与现状 ,提出了制浆新工艺———液相线铸造 .通过对 2 61 8及 70 75铝合金的实验研究表明 ,采用液相线铸造法可以获得均匀、细小的非枝晶 ,其晶粒尺寸小于 50 μm ,该铸造组织经二次加热后完全转变为均匀、细小的等轴晶 ,是完全适合触变成型的理想的半固态组织 .液相线铸造制浆技术具有工艺简单、投资省、生产效率高、适合大规模工业化生产等优点 ,尤其对变形铝合晶半固态浆料的制备具有独特优势 . 展开更多
关键词 半固态金属 铝合金 液相线铸造 组织
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半固态金属成形应用的新进展与前景展望 被引量:60
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作者 毛卫民 赵爱民 钟雪友 《特种铸造及有色合金》 EI CAS CSCD 北大核心 1998年第6期33-36,共4页
论述了半固态金属坯料制备工艺、成形工艺、半固态金属成形件的性能和半固态金属成形在一些发达国家应用的最新进展,并展望了半固态金属成形在我国应用的前景及意义。
关键词 半固态金属 流变成形 触变成形 力学性能 铸造
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半固态金属成形的本构关系 被引量:12
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作者 闫洪 夏巨谌 +2 位作者 王高潮 胡国安 李海江 《材料导报》 EI CAS CSCD 2002年第11期8-10,共3页
将半固态金属成形的本构关系的描述分为低固相率的流变模型和高固相率的应力应变率关系,阐述了其发展过程中具有代表性的材料本构关系,为深入研究半固态金属成形工艺提供了参考。
关键词 半固态金属成形 本构关系 流变模型 应力 固相率 塑性成形 铸造
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铝合金半固态加工技术应用 被引量:20
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作者 张奎 刘国钧 +7 位作者 张景新 徐骏 石力开 崔代金 吴绪平 雷健 郑宇新 袁序弟 《中国有色金属学报》 EI CAS CSCD 北大核心 2000年第S1期135-140,共6页
对于垂直式电磁搅拌器 ,提高搅拌效率的最有效措施是减少漏磁通。对于通常的Al Si类合金的半固态加工坯料 ,在足够的搅拌强度下 ,熔体冷却速度控制在 0 .5~ 3.0℃ /s可得到较好的组织。在二次加热时共晶体中的针簇状Si相通过扩散溶解... 对于垂直式电磁搅拌器 ,提高搅拌效率的最有效措施是减少漏磁通。对于通常的Al Si类合金的半固态加工坯料 ,在足够的搅拌强度下 ,熔体冷却速度控制在 0 .5~ 3.0℃ /s可得到较好的组织。在二次加热时共晶体中的针簇状Si相通过扩散溶解到α相中 ,Si相本身变成细小颗粒 ,初生α相在共晶熔化后才开始球化。对于AlSi9Cu3合金 ,其共晶相在二次加热熔化后重新凝固时 ,Si相呈细小颗粒析出 ;对于A357合金 ,仍然生成针簇状组织。与常规压铸相比 ,半固态压铸内浇道厚度要增加 2~ 3mm ,压射比压要高 5~ 2 0MPa,才能保证充型完好。 展开更多
关键词 铝硅合金 半固态金属 电磁搅拌 半固态压铸
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镁合金半固态成形的现状及发展前景 被引量:29
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作者 李元东 郝远 +1 位作者 陈体军 闫峰云 《特种铸造及有色合金》 CAS CSCD 北大核心 2001年第2期77-78,共2页
从非枝晶组织的制备、二次加热、半固态成形方法等 3方面介绍了镁合金半固态成形技术目前的研究与应用现状 。
关键词 镁合金 半固态成形 非枝晶组织 二次加热 半固态金属
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电磁搅拌对弹簧钢60Si_2Mn凝固组织的影响 被引量:13
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作者 赵爱民 毛卫民 +2 位作者 崔成林 李彦军 钟雪友 《北京科技大学学报》 EI CAS CSCD 北大核心 2000年第2期134-137,共4页
利用金相观察了电磁搅拌对弹簧钢60Si2Mn凝固组织的影响情况,并讨论了形成机制. 结果表明:在凝固过程中进行电磁搅拌,引起熔体的强烈流动,使液相区的温度场和溶质含量 趋于均匀;凝固时奥氏体的一次臂生长速度减慢,消除弹... 利用金相观察了电磁搅拌对弹簧钢60Si2Mn凝固组织的影响情况,并讨论了形成机制. 结果表明:在凝固过程中进行电磁搅拌,引起熔体的强烈流动,使液相区的温度场和溶质含量 趋于均匀;凝固时奥氏体的一次臂生长速度减慢,消除弹簧钢60Si2Mn一次结晶组织中发达的 柱状树枝晶层;而且随着搅拌功率的加大,弹簧钢一次结晶奥氏体的粒化或非枝晶化(nonden一 drite)程度提高:电磁搅拌使弹簧钢凝固的晶核增多,一次结晶组织得到细化. 展开更多
关键词 电磁搅拌 60SI2MN 凝固组织 弹簧钢 半固态成形
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数值模拟在半固态金属加工中的应用 被引量:22
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作者 谢水生 沈健 张学军 《塑性工程学报》 EI CAS CSCD 2000年第1期6-10,共5页
本文在综合有关半固态金属加工过程模拟文献资料的基础上 ,简要分析了半固态金属加工过程模拟的特点 ,对数值模拟技术在半固态加工方面研究的发展、现状和趋势进行了详细的评述。
关键词 数值模拟 半固态 金属加工 模拟 铸造 凝固
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A2017半固态合金二次加热工艺及组织演化机制 被引量:11
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作者 王顺成 温景林 +2 位作者 陈彦博 曹富荣 李英龙 《铸造》 CAS CSCD 北大核心 2004年第8期590-594,共5页
相同加热温度条件下,随着保温时间的延长,晶粒逐渐长大和球化,液相分数增加;提高二次加热温度,晶粒长大和球化速度加快。在620~625℃加热,保温40~60min,可获得由均匀球形晶粒悬浮于液相组成的半固态组织,晶粒大小为70~90μm,液相率为... 相同加热温度条件下,随着保温时间的延长,晶粒逐渐长大和球化,液相分数增加;提高二次加热温度,晶粒长大和球化速度加快。在620~625℃加热,保温40~60min,可获得由均匀球形晶粒悬浮于液相组成的半固态组织,晶粒大小为70~90μm,液相率为40%~45%。而常规铸造枝晶A2017合金坯料二次加热后仍然保留粗大的枝晶网络结构。半固态合金锭坯二次加热初期晶粒的熔合合并是晶粒长大的主要方式,相界面能的升高和相界面表面张力是组织演化的主要驱动力。 展开更多
关键词 半固态金属 二次加热 A2017合金 组织演化
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