Wen LIU
材料科学技术（英文）
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.PartⅡ：This study investigates the rheological behavior 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 behavior of SSM slurries was described by an analytical model in terms of micro structural parameters, which consist of effective solid fraction, particle size and shape, and flow parameters such as mean velocity, fluctuation 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 value is less than 10%. The results of experiment and theoretical calculation also indicate that the micro structural parameters and flow parameters are two major factors that affect the apparent viscosity of semi-solid alloys, and fluctuation velocity and relative velocity between liquid and solid phase are the key factors to distinguish between steady and transient rheological behaviors.
关键词:
Semi-solid metal
,
能量耗散
,
流变
,
表观粘度
,
模型
Miaoquan LI
,
Shankun XUE
,
Aiming XIONG
,
Shenghui CHEN
材料科学技术（英文）
Hot compression was conducted at a Thermecmaster-Z simulator, at deformation temperatures of 800~1040℃, with strain rates of 0.001~50 s-1 and height reduction of 50%. Grain size of the prior α phase was measured with a Leica LABOR-LUX12MFS/ST microscope to which QUANTIMET 500 software for image analysis for quantitative metallography was linked. According to the present experimental data, a constitutive relationship for a TC6 alloy and a model for grain size of the prior α phase were established based on the Arrhenius' equation and the Yada's equation, respectively. By finite element (FE) simulation, deformation distribution was determined for isothermal forging of a TC6 aerofoil blade at temperatures of 860~940℃ and hammer velocities of 9~3000.0 mm/min. Meanwhile, the grain size of the prior α phase is simulated during isothermal forging of the TC6 aerofoil blade, by combining FE outputs with the present grain size model. The present results illustrate the grain size and its distribution in the prior α phase during the isothermal forging of the TC6 aerofoil blade. The simulated results show that the height reduction, deformation temperature, and hammer velocity have significant effects on distribution of the equivalent strain and the grain size of the prior α phase.
关键词:
Titanium alloy
,
null
,
null
,
null
,
null
李立新
,
李彬
上海金属
在工艺润滑和高速钢工作辊的影响下,CSP生产线的轧制力不能简单地用热轧公式计算.将Sims公式和Hill公式进行加权求和得到应力状态系数,结合CSP生产线生产数据,以预测与实测轧制力差值最小为目标定义目标函数,采用变量轮换的优化方法,找到使得目标函数最小时的摩擦系数.以此摩擦系数为因变量,建立摩擦系数的模型和轧制力数学模型.结果表明:Hill公式更适合CSP轧制力的计算,预测值与实测值的相对误差仅在3％左右,模型精度较高.
关键词:
CSP生产线
,
摩擦系数
,
轧制力
,
模型
张慧书
,
战东平
,
姜周华
,
张洋鹏
,
陈韧
上海金属
转炉终渣成分对后续炼钢过程将产生重要影响.采用Visual Basic 6.0进行编程,应用克服BP神经网络缺陷的小波神经网络,建立了网络结构为8-10-6,其中隐含层传递函数为Morlet型函数,输出层传递函数为S型函数的120 t转炉终渣成分预报模型.采用550炉数据进行模型训练,经20炉数据现场验证表明,模型预报结果各个成分有85.8％的平均相对误差在0.1以内.模型预测精度较高,可以满足工厂实际使用需要.
关键词:
小波神经网络
,
转炉渣
,
模型
,
预测
,
渣成分
刘鹏
,
王松
,
陈梦鹤
上海金属
Ficham和Richardson提出硅酸盐熔渣的结构包含3种不同的氧离子,即非桥氧、桥氧和自由氧,张国华又把氧离子细分为6种类型.基于张国华的模型,用6种不同类型的氧离子表示熔渣的结构,针对电渣重熔渣系高氟化钙的特点,重新对氟化钙的模型参数进行回归.利用修正后的模型,计算含TiO2的电渣重熔渣系黏度,计算结果和实验值符合较好.同时还从文献中查找了一些黏度数据,分别利用NPL模型、Riboud模型和修正后的模型进行计算,对比后发现修正后的模型能够很好地预测电渣重熔渣系黏度.
关键词:
电渣重熔
,
渣系
,
黏度
,
模型
杨坤好
,
居建国
,
王晓蕾
,
左龙彦
,
谢钟清
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2014.05.001
综述了树脂基导热复合材料的导热机理及模型、种类以及影响因素,列举了金属、陶瓷、碳质以及混杂填料4种树脂基导热复合材料,分析探讨了树脂基体种类,导热填料种类、形状和用量,导热填料/树脂基体界面以及制备工艺等对复合材料导热性能的影响,并对高导热树脂基复合材料的应用前景和发展趋势进行了展望.
关键词:
高导热
,
树脂基复合材料
,
导热机理
,
模型
