钢包互用条件及影响因素

为深入研究炼钢厂多台连铸机间钢包产生互用的条件及影响因素,以H炼钢厂的钢包为研究对象,简要解析了钢包运行过程及运行时间。分析了钢包周转次数、周转数与浇铸炉次数之间的关系;运用甘特图模拟出两台连铸机浇次重叠时间为50 min条件下的钢包运行过程。研究表明：钢包产生互用的前提条件为钢包在先停浇连铸机不再承担运输任务,且先停浇连铸机的钢包空包结束时间应在后开浇连铸机钢包的重包开始时间之前。分析了浇次重叠时间对钢包互用的影响,结果表明：浇次重叠时间内连铸机浇铸的钢包数少于围绕连铸机周转的钢包数时才能产生钢包互用。研究了连铸机单炉浇铸时间与钢包周转周期对钢包互用的影响,结果表明：科学控制钢包周转周期和连铸机单炉浇铸时间,合理匹配二者关系,可使浇次最后不需要周转的钢包数增加,提高钢包的互用几率。     

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.     

Analysis of ultimate load and mechanismsof failure in large cast steel joints

Based on a project of pipe truss roof framing in Chengdu, the ultimate limit state analysis is performed on cast steel joints by using FEM, in which Linear hardening elastic-plastic constitutive model is considered. The results show that, the joint has a great accumulation of plastic strain in ultimate loads, and the point of maximum stress is different from that in elastic with the development of the yielding zone. The paper propoes to use rate-type tensor for the large strain geometric nonlinear problem, shows the criterion of failure formation , and indicates that its essential to apply limit state analysis to the determination of the weakest location on cast steel joint design, which provides basis for understanding the failure modes and failure mechanism of cast steel joint and the cast steel joint design.     

Effect of nitrogen on microstructure and properties of SWRH82B wire rod

The microstructure, mechanical properties, tensile fractures and the precipitation of the second phase of vanadium microalloyed wire rods with different nitrogen contents are studied by hydraulic universal testing machine, scanning electron microscopy(SEM) and transmission electron microscopy(TEM) . The results show that the interlamellar spacing of pearlite is smaller in high nitrogen steel; the high nitrogen steel has higher yield strength, tensile strength and lower elongation and reduction of area; there are more inclusions on the tensile fracture surfaces of the high nitrogen steel; and in high nitrogen steel, the size of precipitation, mainly precipitating at dislocation or the boundary of austenite, is finer than that of low nitrogen steel, what is more, fine V(C,N) particles are concluded in the precipitations.     

Calculation model for the turnover number of steel ladle based on casting schedule

In order to realize optimization of production organization and put forward a reasonable calculation model for the turnover number of steel ladle, the turnover process and time of steel ladle are analyzed with steel ladle of Q steelmaking plant. Gantt charts of steel ladle turnover for single casting schedule and double casting schedule are drawn. Calculation model for turnover number of steel ladle is put forward by analyzing the relationship between casting schedule and the turnover time of steel ladle, and the accuracy of the model is verified by simulation method. Researches show that the turnover number of steel ladle can be reduced 1-2 by adjusting cast starting time, and have significance for the optimization of steel ladle production organization.     

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.     

The Study on Non-Metallic Inclusions in High Speed Tcol Steel M2Al

The motphology amount,size and distribution of non-metallic inclusions in highspoed tool steeis M2Al and M2 have ben studyed by oberving the blocksample and electrolytic ex-tracting inclusion powder with quantitative microscope,SEM and chemical analyzing techniques.Itwas shown that the amount,sise and nonuniformity of distribution of inclusions all increase evi-dently because of the addition of aluminum,and the situation is caused mainly by the increase of theamount of Al2O3 inclusion and its composites.     

含铈耐热钢凝固过程中的夹杂物行为

建立了稀土耐热钢凝固过程中夹杂物析出与溶质元素微观偏析的耦合热力学模型,并通过工业试验与高温模拟实验验证了模型的准确性。利用该模型,依次考察了铈添加量,初始氧含量,初始硫含量对253MA耐热钢凝固过程中夹杂物析出行为的影响作用规律。在本模型条件下,随着铈添加量的增加,钢中的SiO2与MnS消失,且凝固过程中开始析出CeN;随着初始氧含量的增加,钢中开始析出Ce2O3,SiO2及MnS,其中SiO2与MnS在凝固过程中析出;随着初始硫含量的增加,钢中的Ce2O3消失,钢中开始析出Ce3S4与MnS,在凝固过程中析出的Ce3S4逐渐在液相线温度以上析出。研究工作对于稀土耐热钢连铸水口结瘤问题的解决具有理论指导意义。     

生物质炭配施蚯蚓粪对水稻产量及养分吸收的影响

生物质炭配施蚯蚓粪（BEC）可增加土壤碳氮投入,促进作物增产及营养元素的吸收利用。设置3个生物质炭用量梯度（B₀：0.0g/kg,B₁：6.0g/kg,B₂：30.0g/kg）和3个蚯蚓粪用量梯度（M₀：不施蚯蚓粪,M₁：1%蚯蚓粪,M₂：5%蚯蚓粪）,于2018和2019年进行盆栽试验,以研究BEC对水稻产量和营养元素吸收的影响。结果显示,2019年不同处理水稻各部位生物量均高于2018年,籽粒的氮和磷吸收量增加,但吸钾量在B₂和M₂处理中降低;2018和2019年籽粒生物量与BEC的碳投入量间呈极显著相关（P<0.01）;2019年籽粒生物量与氮投入量显著相关（P<0.05）;BEC产生的碳、氮投入量与氮素收获指数呈正相关,与2018年磷素收获指数间呈不显著负相关,与2019年钾元素收获指数呈显著负相关（P<0.05）,BEC对不同元素吸收利用的影响存在差异。生物质炭配施蚯蚓粪促进了水稻生长,有利于提高化学元素利用率,是培肥中低产田、提高作物产量和养分利用率的有效措施。     

Computer Simulation for Analysing the Melting Action of Mould Powders During Continuous Casting

When analysing the performance of casting powders in a specific casting machine, the thickness of liquid slag is a very important parameter. If the liquid slag thickness is not kept above a certain minimum value during the continuous casting operation,the surface and internal quality of the cast products will be jeopardised because lubrication between the strand and the mould is impaired . It is necessary, therefore , to choose the appropriate type of mould powder .In the industrial experiments, it is very difficult and expensive to study this sensitivity by introducing controlled variation in one parameter while keeping all the other constant. Numerical and computer simulation methods are used in the study .They can predict the liquid slag thickness developed above the liquid steel and distribution of the temperature. The sensitivity of the liquid slag thickness to variations can be determined in the material properties of the mould powders.     

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.     

免耕抛秧水稻的大穗优势及形成机理研究

在田间条件下,连续4年对免耕抛秧水稻的大穗优势及形成机理进行了研究。结果表明,与常耕抛秧水稻相比,免耕抛秧水稻的每穗总粒数更多,表现出明显的大穗优势。免耕抛秧水稻的分蘖位较低,后期积累干物质和养分的能力强,后期生理代谢旺盛、生理功能强,剑叶衰老慢,能充分保证籽粒生长等是免耕抛秧水稻大穗优势形成的内在生理原因。     

Quantitative study on solid slag film’s crystallinity of mould fluxes by using DSC method

The method to determine the crystallinity of solid slag film is established by analyzing the DSC curve of solid slag film and corresponding quenched slag. The accuracy of the method is investigated by measurements of prepared samples whose crystallinity is given. In addition, the solid slag films of mold slags used to cast medium carbon steel and low carbon steel are obtained by heat flux simulator in laboratory, and the crystallinity of the two kinds of slag film are also measured by DSC method. Experimental results indicates that the crystallinity of solid slag film can be determined by comparing the crystallization enthalpy of solid slag film and corresponding quenched slag during heating process, and the relative error is within 5.03%. For medium carbon steel, the crystalline fraction of solid slag film is 88.6%, while the crystalline fraction of solid slag film corresponding to low carbon steel is 55.0%. The results are consistent with actual structure of solid slag films.     

Finite Element Analysis and Experimental Research on Pedestal of PC Beam for Light Railcar

In design of light railcar used freely supported beam, the cast steel pedestals will bear complex loads, which include weight, acceleration and wind, etc. Because of pedestals' peculiarity and complexity, the strength of the pedestals play an important role in safety of light railcar. So it's necessary to analyze their stress and deformation in order to insure safety of light railcar. Up to now, finite element analysis is still the most effective means. By studying cast steel pedestal with finite element method, 3-D finite element models of fixed and kinetic pedestals were built, and the loads and boundary condition of pedestals were analyzed. By means of finite element analysis software, the contact and von mises stresses were obtained and deformation were resolved. As a result of analysis, the tow of pedestal can fulfill requirement of use in light railcar, the contact stress and von mises stress are not exceeded limit stress strength of materials. There is enough static strength for the structures of pedestals. For verifying theoretical analysis result, the fatigue test was carried out, with examining the testing points locating on the pedestals, the stress and deformation data were measured. By comparing between theoretical analysis and test data, the experimental results show calculated and testing results can meet the case well which assure the reliability of finite element analysis. But in the result, there are differences in deformations of them. The reason may be that boundary conditions and loads are not same between analysis and experiment.     

Disintegration of microsporocytes in a male sterile mutant of <Emphasis Type="Italic">Brassica napus</Emphasis> L. is possibly associated with endoplasmic reticulum-dependent autophagic programmed cell death

The mechanism of anther abortion in a male sterile (ms) line (Longyou 9S) of Brassica napus L. was evaluated by a combination of light and electron microscopies. Light microscopy showed that the tapetal cells of the ms line appeared smaller than those of its fertile line, sporogenous cells were rich in vacuoles, and pollen mother cells dismantled before the tetrad stage. Electron microscopy demonstrated that sporogenous cells were also rich in very long, plate-shaped endoplasmic reticulum cisternae that actively encircled portions of cytoplasm with organelles. In later stages, many large membrane-bound inclusions were observed in the sporogenous cells. These membrane-bound inclusions were lined by single or multiple layer(s) of the endoplasmic reticulum membranes and contained vacuoles, ribosome, plastid, mitochondria, small membrane-bound inclusion, and/or intact nuclei. In meiotic interphase and early meiosis prophase I, many vesicle aggregations and multivesicular bodies containing numerous vesicles appeared in pollen mother cells. More interestingly, some of the multivesicular bodies lay in deep cytoplasm or near cell wall, and some appeared fused with plasmalemma and released the inner vesicles out of plasmalemma. Such released vesicles gradually dispersed and later disappeared. The observations suggest that active endoplasmic reticulum-dependent autophagic programmed cell death and multivesicular body-dependent polar vesicle trafficking are probably present in the studied male sterile line.     

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.     

β-环糊精对毒死蜱的分子识别研究

为研究β-环糊精(β-Cyclodextrin, β-CD)在农药高效利用和环境保护等领域中应用的可行性,本试验采用研磨法、超声波法和饱和水溶液法制备了β-CD与毒死蜱的包合物,并利用紫外光谱、差示热分析和红外光谱法分析验证了包合物的形成以及毒死蜱在β-CD溶液中的包结行为。结果表明饱和水溶液法的包合效果最佳,包合率达到45.8%;最佳条件为：投料比为1：1（摩尔比）,恒温搅拌时间为3h,包合温度为60℃;验证结果表明反应形成了包合比为1：1的包合物,且稳定常数为K=33.33 L/mol,吉布斯函数△G =-8.69 KJ/mol;本试验证明了β-CD能够对毒死蜱产生包合作用,毒死蜱分子部分功能基团进入了β-CD空腔,并形成了稳定包合物。     

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 on Coaction of Concrete Cast in place Box ArchRing and Arch Centering

The construction method of concreting layer by layer and segment by segment could reduce the use of steel and save construction cost, when concrete box arch ring was built cast in place with aid of arch centering. According to the simulation of large scal     

Prediction Model of Intermixing Slab Length During Continuous Casting Grade Transition Process

In order to increase decision accuracy of the intermixing slab length and position, and decrease the slabs which are offgraded or scrapped. Water model experiments were conducted to simulate the continuous casting grade transition process of No. 2 continuous caster at Bao Steel. The dimensionless concentration profiles along slab length with different continuous casting conditions were measured. Based on the profiles a mathematical model was developed to predict the final composition distributions and length of intermixing slab. Comparison of predicted dimensionless concentration profile with plant data shows that the precision of the model is considerably satisfied to meet the need of steel grade transition evaluation.