铝合金半固态浆料中球形颗粒的演变

用AlSi7Mg0.6半固态浆料进行实验,研究球形颗粒的演变机理.在略高于液相线温度下水淬的样品中结晶相主要为枝晶,而采用旋转圆筒的方式来搅拌熔体使其冷却到半固态温度范围内时样品的结晶相完全球化.在铸造前进行较长时间的内冷却和搅拌,可以得到较高的固相分数.不同大小的枝晶碎片的存在表明,在搅拌过程中,初始的固相分数形成后不再受冷却的影响.     

强韧性白口铸铁抛丸叶片的研制和应用

本文研究了等温淬火热处理对亚共晶白口铸铁抛丸叶片组织、性能的影响。研究结果表明,采取等温淬火热处理工艺,叶片的冲击韧性有较大辐度的提高,同时耐磨性亦有明显的改善,延长了使用寿命,具有较好的技术经济价值。     

预制桩及搅拌桩在东溪水闸加固中的应用

通过对东溪水闸闸室地基强度的验算及对地基表层抗滑移定及深层抗滑稳定的分析，提出了采用预制桩及搅拌桩抗滑墙除险加固闸基的办法，此方法在满足安全的前提下，可节省投资，缩短工期，为闸基稳定加固处理提供了借鉴的经验。     

一次盐水精制工艺操作条件的研究

对石灰-碳酸铵法精制一次盐水的工艺操作条件、特别是对搅拌因素的影响作了研究,得出最好的操作条件为:加灰一级搅拌,速度梯度值1400S~(-1),搅拌时间15S,二、三级搅拌共10min,速度梯度值.750S~(-1),絮凝剂加入搅拌,速度梯度550S~(-1),搅拌时间6S,在此条件下,500ml 量筒试验,5min 时澄清液,其浊度为5PPM 左右。     

Experimental Modelling using Low Melting Point Metallic Melts: Relevance for Metallurgical Engineering

This paper describes model experiments with liquid metals of low melting point as an important tool to investigate the flow structure and related transport processes in melt flows being relevant for metallurgical applications. Three examples have been selected to demonstrate the benefit of such experiments, namely the electromagnetic stirring of a metallic melt in a pool, the directional solidification of Al‐Si alloys under the influence of an electromagnetically driven flow and the behaviour of a liquid metal bubble plume if a vertically travelling field is applied. Results of flow measurements are presented and the relevance for metallurgical processes is discussed.     

Numerical Modeling of Inclusion Removal in Electromagnetic Stirred Steel Billets

To investigate the inclusion removal in billets cast under electromagnetic stirring (EMS) influence, a numerical model has been developed to compute the magnetic field, the Lorentz force, the steel flow velocities, and the particle transport within the liquid pool. The electromagnetic field was described by the Maxwell equations and the finite element method was applied using a commercial package. The turbulent fluid flow was described by the Navier‐Stokes equation and by the Reynolds Stress model and the finite volume method was applied using another numerical package. The time average of the Lorentz force was calculated in each element center and this value was applied as a body force in the Navier‐Stokes equation. The magnetic flux density profile was compared with the data obtained in the stirrer of the steel plant. The particle transport model includes the drag force, the buoyancy force and the random walk model, to include the turbulence effects on the particle trajectory. The inclusion removal was calculated and analysed in function of casting speed and stirring current for one size section of mold. The inclusions considered in the calculations have a fixed density and four values of diameter. The numerical results of the electromagnetic model are in agreement with the experimental measurements. A good relationship between the electromagnetic model and the fluid flow model could be shown. An interesting effect is the break of the rotation motion due to the EMS by the jet from the nozzle. The fraction of inclusions removed by the top surface of the mold was improved due to the EMS.     

狭缝式透气砖内气流速度分布规律及阻力研究

建立了狭缝式透气砖内气体流动速度和阻力的数学模型;忽略质量力时,对定常流动不可压缩流体连续方程进行了简化,并进行了数值计算.结果表明,其速度沿狭缝厚度方向按抛物线规律分布,狭缝中心速度最高,流动状态一般为层流;沿程阻力大小与狭缝大小、供气压力、透气砖长度等存在密切关系.为透气砖的设计提供了相关理论依据,可资参考、借鉴.     

小方坯连铸结晶器电磁搅拌的数值模拟

借助有限元分析软件ANSYS,对150mm×150mm小方坯连铸结晶器电磁搅拌在电流为150A,频率变化情况下的钢液内部磁感应强度和电磁力进行了数值分析,并分析了结晶器厚度对钢液内部磁场的影响以及不同时刻钢液内部电磁力的分布。模拟结果表明,在结晶器电磁搅拌时,同一个断面上,4个角部的磁感应强度最大;随着频率的增加,钢液内部磁感应强度降低,钢液边部电磁力在4~5Hz时最大;钢液内部的电磁力在1个周期的不同时刻,形成了同一个方向的力偶,在这个力偶的作用下,完成了对钢液的搅拌;结晶器厚度对钢液内部磁场影响很大,厚度增加,钢液内部磁感应强度降低。     

Finite Element Analysis of 3D Electromagnetic Field in Bloom Continuous Casting Mold

Threedimensional finite element model of electromagnetic stirrer was built to predict magnetic field in a bloom continuous casting mold for steel during operation. The effects of current intensity, current frequency, and mold copper plate thickness on the magnetic field distribution in the mold were investigated. The results show that the magnetic induction intensity increases linearly with the increase in current intensity and decreases with the increase in current frequency. Increasing current intensity and frequency is available in increasing the electromagnetic force. The Joule heat decreases gradually from surface to center of bloom, and a maximum Joule heat can be found on corner of bloom. The prediction of magnetic induction intensity is in good agreement with the measured values.