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.     

STUDY ON HEAT TRANSFER MATHEMATICAL MODEL BETWEEN BILLETS AND ROLLERS FOR THE SECONDARY COOLING ZONE IN BILLET CONTINUOUS CASTING

A mathematcal model of heat transfer between the billet and the roller for the seeondary cooling zone in billet continuous casting is established. By means of the simulated test,a regres sion relation between the heat flow from the billet into the roller and the surface temperature and cast ing speed and spray water density obtained. The calculated theoretical values for change of surface temperature are in agreement with the measured data, these studies may contribut to the quantitative analysis and the calculation of the heat transfer of the secondary cooling zone.     

Nondestructive Test of Surface Defect of Hot Slabs Based on Machine Vision at High Temperature State

Aimed at the problem of online detection of continuous slabs surface defect at high temperature, The CCD shutter control model was established using machine vision technology and equipment at high temperature states. The default clustering algorithm was provided. The CCD imaging equipment with dual cool modes of water and air was selected to ensure continuous work at high temperature conditions. The slab width of 3 000 mm can be detected, and the system can effectively restrain the influence of noise signals brought by oscillation marks on the surface of slabs and realize monitoring and clustering of the slab surface default.     

The Numerical Simulation Commercial Software for Secondary Cooling Process in Billet Continuous Casting

A numerical simulation commercial software has been developed by the object-oriented Visual Basic programming language on the basis of the 2D mathematical model of secondary cooling Process in billet continuous casting. Thereby an effective experimenting tool for computer simulation of continuous casting process is gained. By simulation with the software, the caster structures and operating parameters in continuous casting can be designed and optimized. The simulating calculation examples on several casters and its production applications indicate that the commercial software developed has more accuracy, practicability and commonality, as also as simpler operating capability. The simulated results have been successfully applied to the design and production of the high-efficiency modification for several billet casters interiorly.     

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.     

Research and Application of Temperature-field Digitalizing of the Tuyere and Raceway Section in Blast Furnace

It is useful for diagnosing coal combustion status and the tuyere and raceway in blast furnace, at the same time, it is supervision running state to study on temperature-field of also helpful for supervising the structure of oxygen and coal burning apparatus, improving coal combustion technology and coal injection operation. The model between red and green information of true color flame image and temperature is established and two dimension raceway section projection temperature-field are achieved by applying no-touch radiation temperature measurement theory and technology. It is proved with experimentation that the method is effective and feasible, and the testing precision can reach 98.09% compared to the testing result of thermocouple of taking out gas.     

Dynamic Control Arithmetic and Modeling of Secondary Cooling System for ROKOP Billet Continuous Casting

A dynamic control arithmetic and mathematic model of secondary cooling system for ROKOP billet concasting has been developed in view of the changes of casting speed during concasting process and the high fluctuation of surface temperature due to the use of static control method. By means of computer simulation and by comparison between static and dynamic control method, it proves that the latter one is more adaptive to the changes of casting speed, which leads to lower fluctuation of surface temperature.     

Computational Simulation on Temperature Field of Slab Continuous Casting Mold

On the core concepts that the distributing of temperature and solidified slab shell in mold are a stable process, a new method to calculate the temperature field in mold has been promoted. Consequently, a coupling model on fluid filed and temperature field in stable state has also been established. The concept of effective heat capacity is introduced to deal with the latent heat source term from phase transformation. During the programming for computation, the dynamic updating method is also applied to simulate the influence of solidification on physical properties. The resolution results of this model are analyzed and compared with the tested thickness of solidified shell from casting broke out slab, which demonstrates the correctness and applicability of this model to the practical continuous casting process. Additionally, the thickness distribution of solidified shell in slab mold are also studied in detail.     

Development and experiments of direct resistance heating in hot forging

A new hot-forging method by means of direct resistance heating is investigated aiming at the long produce time and large energy consumption of traditional hot forging. The hot upsetting experiments with cylindrical billet of 42CrMo4 are performed. The influences of initial contact force, surface quality of the billet and current intensity on the heating temperature are researched. The results of the experiments show that the billet can be heated quickly to forming temperature by the approach. The relatively low initial contact force is useful to increase the heating temperature. The heating temperature is proportional to the square of the current intensity, and the heating temperature is seriously affected by the surface quality. During the forming process the billet cooling rate is effectively decreased and the forming time is extended in relation to the resistance heating.     

Three dimensional temperature field visualization reconstruction of charge coupled device radiation image

Aiming at the questions of raceway section two dimension temperature distribution from two dimensional image accumulated by three dimensional radiation space and three dimensional temperature reconstruction error caused by limited charge coupled device (CCD) sensors for a sudden spread combustion chamber, the two dimension rectangle interpolation virtual CCD sensor installation algorithm is provided as a new technology for solving the difficulties of installing more CCD sensors and filtered back projection reconstruction error caused by limited projection numbers. The radiation intensity projection data got from flame image collected from the installed CCD sensors and computed virtual CCD sensors is interpolated for filtered back projection to computer intensity distribution and calibrated bi color method is used to calculation temperature in raceway depth direction. The results of experiments on a mini type coal gas furnace and practice test showed that the algorithm is accurate and credible and realized the on line monitoring for sudden spread combustion chamber raceway depth direction. At the same time, the useful information is provided for further studying combustion working state for the sudden spread combustion chamber.     

THE STUDY FOR LARGE INCLUSIONS OF STAINLESS STEEL (1Crl8Ni9Ti) DURING CONTINUOUS CASTING

This paper presents the process of stainless steel ( 1Crl8Ni9Ti) in continuous casting,the components and their shapes,origins and distributions of the large inclusions existing in the steel,as well as the influence on its quality. By the observation through a microscope,the structural analysis adopting x-ray examinating instrument and the measunement for the microzone of billet employing the electronic probe.it has been found that the large inclusions of continuous billet mainly originate from the slag-sweeping of the tundisy and mold. There are mostly spherical-slag in addition to Ti(C.N) in the inclusions. The calculations in theory point out that the siO2in the slag can' t change Ti(C,N) into TiO2,however,it can assimilate with Ti(C.N). The large inclusions affect the quality of the steel plate and tube greatly. As a result,this paper proposes the measures of reducing the large inclusions in the steel.     

ROLE OF BaO IN MOLD POWDER USED IN CHNTINUKUS CASTING KF STEEL

In this paper, the role of BaO in mold powder used in continuous casting of steel is studied. The pricipal content of the study is about the effect of BaO on melting temperature, Viscosity, and capacity of absorbing inclusion and glassing of molten mold powder. Experiment results reveal that to add BaO into mold powder can decrease the melting temperature and viscosity, and prevent the formation of high melting point particle and crystallizing of mold powder, suitable BaO content in mold powder is quite helpful to increase the capacity of absorbing inclusion of molten mold powder, and to improve the lubrication effect of molten powder film between mold and billet.     

Dynamic Control Model for the Secondary Cooling of Slab Casting Based on Neural Networks

A dynamic control model for the secondary cooling of slab casting is presented to reduce the difference between the actual temperature and the goal surface temperature of slab. The model, which is based on the BP neural networks for forecasting the temperature and the fuzzy neural networks for dynamically controlling the water in the secondary cooling in the continuous casting, could timely adjust and allocate the water according to the speed and temperature of slab. A series of tests have been conducted based on inputs of the No. 2 slab caster in a steel plant. It has been shown that the model, which integrate the charateristics of water controlling problem in secondary cooling into the temperature status of slab during the cooling process, can control the water in secondary cooling efficiently and dynamically according to the situation of actual production.     

Numerical Simulation of Temperature Field during the Dissolution-Diffusion Bonding Process to Mending Iron Casting Defects

The common finite element method microcomputer software for simulation of the temperature field is developed by authors. It is used for calculating the temperature field duringthe mending process of iron casting defects by means of the dissolution-diffusion bonding technology. The correctness has been proved by testing results. This software has been used to analyse thecaused of hardness rising in heat effecting zone,and also find out the approach for solving the problem.     

Temperature Field Analysis of Long-span Concrete Box Girders

Taking a two-lane extra large bridge as sample,it is to analyze the real time thermal field and thermal effect on a long-span prestressed concrete box girder. The obtained data is compared with the simulation which is based on a balancing theory of temperature distributions and exchange in box girder exterior surfaces. The results show that the proposed method can emulate the actual boundary conditions precisely, it can satisfy the design analysis requirement of the practice engineering. Based on the emulation of the temperature field, with the ANSYS secondary development technology, FEM modules are developed to analyze the thermal field of the prestressed concrete box girder bridges. The present examples show that the developed modules are effective and useful.     

辽宁陆面温度的反演与实测数据对比分析

为了及时准确地从遥感图像数据中反演出地表温度的变化,针对辽宁地区制定播种计划、确定种植结构等提供技术支持,选取辽宁省作为研究区,利用EOS/MODIS热红外遥感数据和FY-3/MERSI数据与相关的地面气象台站实测数据,建立地表温度反演模型。采用分裂窗算法中的两因素模型和普适单通道算法对辽宁省地表温度进行反演。通过对气象台站实测的地面温度值和反演的温度进行拟合来获取回归方程,再利用反演的温度值模拟真实地表温度。对比2种算法,得出分裂窗算法是更适合进行辽宁地区地表温度的反演方法。     

Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

Research on the Real -time Simulation of Temperature Field for RCC Gravity Dam

The simulation analysis of temperature field under ideal condition can reflects the rule of true temperature field, but accidental factor during construction process will result in difference of the result. This paper studied the Baise RCC Dam with the distributed optical fiber technology and FEM technology, the numerical results were modified with the testing data and the contrastive curves can be obtained for the testing data,ideal simulation data and real -time simulation data. The results indicate that the modified real - time simulation can reflect the true temperature field ; it may serve as a guide for the temperature control.     

Two-dimension Thermal Elasto-plastic and Creep Stress Model for Thin Slab Strand in Continous Casting

The thin-slab continuous casting is an important new technology in the world. The major key of this technology is to assure the good quality and the less crack of thin slab. Thus in this paper a two-dimension thermal elasto-plastic and creep stress (TEPC) model for thin slab strand is developed. The equations between stress and strain are given on thermal creep condition for elastic area, plastic area and the transitional area of thin-slab strand section.The formula of equivalent plasto-strain increment is obtained. The boundary conditions of the model given is fairly accurate. Therefore, the TEPC model is possessed of higher precision, and the model is also used to analyze the stress and strain distribution of strand in continuous casting.     

Development of mold fluxes for welding rod steel at the Shuicheng Iron and Steel (Group) Co., Ltd.

The solidification characteristics of steel are analyzed with the aim of explaining the appearance of serious surface depressions and frequent breakouts when casting billet H08 steel at the Shuicheng Iron and Steel (Group) Co., Ltd., P.R. China