Finite Element Method of 3D Stable Heat Conduction of Steel Fluid in Continuous Casting Moulds

The heat transfer of steel fluid in continuous casting mould is a stable process and can be depicted with three-dimensional stable heat conduction equation depending on tension speed. The corresponding finite element equation, including the first, second and third boundary conditions, is deduced out with Galerkin residual method. The coded FEM program is used to analyze the temperature distribution of Q235 steel in continuous billet casting mould. The method proposed is a foundation of thermo-mechanical coupled analysis for the formation of solidified shells and stress in the shells in continuous casting.     

DETERMINATION OF METALLIC IRON IN HIGH TITANIUM SLAG BY HEADSPACE GAS CHROMATNGRALHY

The following details are discussed in the present paper, after high titanium slag and H3PO4 is put in the closed system,the .reaction takes place under controlled temperature conditions, and the gas produced is collected. The two phases of gas liquid attain kinetic equilibrium, ihe gas above the liquid is used to make GC analysis with the aid of chromatographic column of 5A molecular sieve, TCD and N2 30ml/min. Satisfactory quantitative results can be achieved with simple instruments and uncomplicated operation technique.     

Effect of B2O3 on the physico-chemical properties of mold slag used for high-Al steel

A new mold slag with low content SiO2 and high content Al2O3 is designed in order to avoid or alleviate the reaction between Al and SiO2 during the continuous casting of high-Al steel, the acidity of this slag is adjusted by adding B2O3, and the effect of B2O3 content on the fusion property, viscosity property and heat transfer characteristics through the mold slag film of the mold slag is analyzed. The results show that the fusion temperature, viscosity, viscous flow activation energy decrease and heat flux through the slag film increases with the increase of B2O3 content in the range of 4%~10%; temperature time transformation (TTT) diagrams move to longer incubation time with the increase of B2O3, while the crystallization speed of mold fluxes decreases; under this experiment condition, the precipitation of CaF2 crystals can be restrained by the increase of B2O3 content in the mold slag.     

Using Electro slag Melting Process of Cast Molten Iron To Produce Ductile Cast Iron

This paper introduces experimental results of the ESM of cast iron in the laboratory and pilot plant based on predecessor's work by molten CaF 2-based slag systems containing MgO , CaO and RexOy. The results show that the desulfurization ,inclusion removal and gas elimination of the ESM have obvious effects on making iron liquid purified and producing high quality casting ,and indicate that the ESM of cast iron may essentially improve the traditional process of cast molten iron melting as a new technique for making high quality ductile cast iron.     

Control model for secondary cooling of continuous casting based on compensation temperature of the difference between liquidus and solidus

During continuous casting process, the composition of molten steel often varies with different heats, which leads to the big fluctuation of billet surface temperature when the traditional parameter water control model is applied to control the process. Additionally, it is difficult to keep the temperature at the straightening point of the billet within a reasonable range. Given above consideration, a new control model for secondary cooling of continuous casting based on compensation temperature of the difference between liquidus and solidus has been presented. Meanwhile, the temperature field of the billet is simulated with both the parameter water control model and the new secondary cooling control model, and the results indicate that the new control model for secondary cooling of continuous casting could perform better when it is used to control the surface temperature at straightening points of billet, thereby ensuring the quality of the billet.     

Preparation of the supplementary cementitious material offerronickel submerged arc furnace slag and its properties

The ferronickel submerged arc furnace slags are stored up more and more, as a result, seriously influenced the sustainable development of the nickel industry. By grinding, the ferronickel submerged arc furnace slag is mechanically activated, then can be used as supplementary cementitious material, thus a comprehensive utilization way of ferronickel submerged arc furnace slag is developed. Using such processed slag to replace cement from 10% to 40% in mass, with the increase of replacing dosage, the water demand of standard consistency of cement paste is lowered, the fluidity of mortar is raised; the compressive strength of mortar is decreased; the flexural strength is increased followed by a decrease after the dosage is above 10%, the ratio of flexural strength to compressive strength is increased. The experimental results indicate that the ferronickel submerged arc furnace slag can be used as supplementary cementitious material and has an increase of flexural strength and effect of plasticizing and water reducing.     

Prediction of the Leakage of Aluminium Alloy Casting and It''s Prevention

Two aspects of the study on the leakage of aluminium are introduced after the leakage mechanism of aluminium alloy casting is described. Three mathematical models, criteria function models, continuing equations-Darcy's law models, hydrogen diffusion-controlled pore growth models, are studied. Some measures of predicting leakage of casting in practice are summarized, such as the treatment of aluminium liquid and the adoption of new technics, Many different models of pore formation and growth have been proposed, however, each of these models has limitation and is not precision enough. Measures in practice have certain significance to the study of predicting leakage of casting, however, to obtain these measures cost a lot of time, manpower and material resource. In order to predict pore formation and growth of aluminium casting more precision, these mathematical models and practical measures should be integrated felicitously in different condition.     

Reliability Analysis of Ultimate Bearing Capacity of Concrete Filled Tube High Piers

To deal with the contradiction between accuracy and time consuming, a model of reliability analysis of CFT was proposed based on the response surface and nonlinear finite element method, And Initial geometric imperfection was induced by consistent mode imperfection method.The reliability index and sensitivity coefficients of CFT high piers were invested by the proposed model.The effects of slenderness, eccentricity and diameter thickness ratio on reliability index of concrete filled tube high piers were studied by parameter analysis method.Meanwhile, the influence of geometric nonlinearity was also analyzed and the reliability of CFT high pier could be affected by factors mentioned above.Based on the analysis, several suggestions for improving the reliability of CFT high piers were proposed.     

RESEARCH ON THE PLUX FOR CONTINUOUS CASTING THE STEEL CONTAINING ALUMINUM

The changes of Al2O3 and the properties, such as basicity, metting point and viscosity, of the mould flux when continuously casting the steels containg Al are discussed. In order to obtain a stable quality in the flux, the functions of content MnO are also studied. As a result, a reasonable composition of flux for this purpose is suggested.     

3-D Finite Element Analysis of Solidified Shell in Molds for Continuous Casting of Thin Slabs

A three-dimentional thermal elastoplastic contact FE analysis model of solidifiedshell in moulds for continuous casting of thin slabs is set up, based on the known geometry of theshell and the temperature distribution in the shell. We in turn obtain the stress and Strain distributions of the solidified shells formed in lSP and CSP moulds,the gap distributions between the Shellsand the mould walls,as well as the curves of cracking index [1] in the shells,which provides afoundation for the design and control of technical parameturs for continuous casting of thin slabs.     

Researches on Melting-points and Visccoity of Mould FluxesWei Qingcheng

The testing of the melting-points and viscosity of BaO-SiO2-CaO-Al2O3(5%)-Na2O(10%)-CaF2(1 0%)six-part slag system is completed. Then the curve charts of the melting-points and viscosity are drawn. Moreover, the mathematical relations between properties andchemical compostion are found out.As a result,the proper range of chemical composition for BaO-contained mould fluxes is therefore presented.     

Short- Line Match Casting Technique for Precast Segmental Construction

The precast segmental construction technique is widely used in the viaduct structures for both vehicular and light rail systems.The present paper highlights the application of short-line match casting technique in fabricating the precast segments for 75m span continuous approach structures of Sutong bridge project.It discusses the functional specifications of the segment mould and its geometry control method.     

Effect of Chemical Composition on Formation Performance of 7050 Alloy Billets

The casting technology of 7050 alloy bilits is researched. that are used to produce slabs for air materials.Because the composition of 7050 alloy is very complex,the Cu and Zn elements contents are higher and Fe and Si impurity elements contents are controlled lower, at the same time ,the specification and the width-thickness ratio are large ,all of above result the tremendous crack trend when casting and bad casting formation performance . The formation performance of 7050 alloy has been improved and qualified billits are obtained by optimizing the composition of 7050 alloy, including raising Fe/Si ratio and Zn/Mg ratio ,reducing Cu content and adopting the joint refinement with block and silk shaped Al-5Ti-1B.     

The Mathematical Model of Cooling and Heat Transfer for the Solidification of Thin Slab during Continuous Casting Process

In the established model, the cooling differences are considered between the surface of inner radius and that of outer radius, and in the transverse direction of thin slab. And the conception for the effective coefficient of spraying water in continuous casting is firstly put forward. According to different casting speeds and different cooling zones, different time step lengths are adopted. In this model the heat transfer differences are thought over among vertical and curved zones, wide and narrow surfaces an well as angular zone of mould. The method of the corrected equivalent specific heat is used to deal with latent heat. The influence of forced convection is considered on heat transfer. Therefore, the model has higher accuracy and is consistent with the practice.     

A Research on Submerged Entry Nozzles for Thin Slab Continuous Casting

In view of the process characteristics of thin slab casting with a vertical-arcmould and super thin submerged nozzles, the fluid flow laws in a mould and in scarch of reasonablesu bmerged nozzle patterns have been physieally simulated. The fluid flow states of several typiealnozzleS in moulds were studied through water model experimen ts. The shape and dimensions of asuitable submerged nozzle have heen optimized for industry trials.     

A Review of Set- retarding and Retarding Measures of Alkali- slag Cement and Concrete

In this paper,the influence of set- retarding on applications of alkali- slag cement and concrete is analysed.Set character of alkali- slag cement and suitability of measures used at home and abtord are discussed.On the basis of above mentioned,it is proposed that the only way to solve the fast- set problem of alkali- slag cement is by incorporating efficient retarders,and researches on mechanism of retarders along with deve loping new composite retarders are the most important topics in the research field of alkali- slag cement and concrete.     

Experimental Analysis of Bearing Capacity of Triangle Hollow Flange Beam

On the basis of Hollow Flange Beam (HFB) which is proposed by Australian researchers, a new pattern triangle hollow flange beam (THFB) is presented. According to the experimental test and finite element simulation, the failure processes of THFB and traditional I-beam under concentrated load are compared, and then the obvious differences between the failure modes of these two type beams are founded. The local buckling is easily occurred for the THFB, while overall instability is easily occurred for traditional I-beam, and THFB possesses have better bending performance and twist resistance than those of traditional I-beam. with the experiments, finite element analysis is carried out by FE software ANSYS, and the FE results agree with the test results. Based on FE models, the parameter analysis is carried out for THFB. The parameters mainly include the thickness of top flange, the width of top flange, the thickness of web and the yield strength of steel. The change rule of the bearing capacity of THFB with different parameters can be achieved by parameter analysis. Finally, based on the above results, the applicability of the calculation formula of Eurocode3 to compute the bearing capacity of THFB is discussed. The results show that it is safe and reliable to adopt the calculation formula of Eurocode3 to compute the bearing capacity of THFB, Whilst the estimation is relatively conservative.     

基于EFAST的盾构隧道安全指标全局敏感性分析

为了分析地铁隧道健康监测中各个指标之间的相互演化作用关系,提出了一种对监测数据进行分析的数据挖掘思路,将傅里叶幅值灵敏度检验扩展法（EFAST）应用于各项指标的全局敏感性分析中。依据现行隧道安全评价规范,建立反映隧道安全状态的指标体系;通过基于粒子群优化的最小二乘法支持向量机（PSO-LSSVM）,模拟构建了各安全指标函数拟合模型,用以描述隧道各安全指标之间相互作用关系;在此基础上,采用EFAST对该模型的指标进行了全局敏感性分析。结果发现,对隧道安全性影响较大的敏感因素有管片接缝张开宽度、管片接缝接触应力和隧道沉降值;另外,还分析了不同的目标参数、不同的参数取值范围、不同的输入参数的分布形式对参数敏感度值的影响,从不同的角度揭示了盾构地铁隧道中参数的相互作用机理的演化规律。     

Successive Approximation by Cascade Auto Disturbance Rejection Controller

An algorithm of parameter identification by model compensation auto disturbance rejection controller is given. It is very efficient to the parameter identification problems of low order systems. At the same time it is not easy to get satisfying parameters of the extended state observer when the order of the controlled system is high. To solve the above problem, we combine in this paper the auto disturbance rejection controller constructed by cascade extended state observer(CESO) with the algorithm of successive approximation. Simulations show it can identify the parameter of systems with known structure effectively. In the meantime, the parameters of CESO are much easier to adjust than those of the former ESO when it is applied to high order systems.     

黄精多糖提取工艺的研究

为研究水提醇沉工艺中不同提取条件对黄精多糖提取率的影响,以优化黄精多糖提取工艺。在单因素实验的基础上,通过四因素三水平正交实验确定工艺参数,紫外分光光度法测定黄精多糖含量。研究表明：温度对提取工艺有极显著影响,提取时间提取工艺有显著影响,提取次数和物料比对提取率影响不大。说明黄精多糖最佳提取工艺条件为：固料比1:15,提取温度90℃,提取时间4 h,提取1次黄精多糖的得率可达3.2248%。