中间包控流装置的发展与应用

近年来随着连铸技术的不断提高，中间包的冶金技术也有了很大的发展。本文主要介绍了连铸中间包内控流装置的几种形式，并对其作用与应用状况做了综述。     

垂直上升管高黏气液环状流流动规律

为了研究高黏气液条件下垂直管环状流动规律,对不同黏度下的流动状态、持液率及压降值进行了实验和数值模拟分析.分析结果表明:液相黏度的增大使液膜厚度增大,气芯液滴数目增多,平均持液率逐渐增大,同时液膜厚度、平均持液率和气芯液滴数目因气体流速的增大而减小;液相黏度的变化对环状流压降有一定影响,总压降和各分压降随着黏度的增大而...     

中引式气力输送系统的特性研究

中引式气力输送系统具有独立、串联和远近距离均适应的优点．通过实验研究,探讨了中引式气力输送系统的流动模式、管道阻力特性和输送压力频谱特性等．实验结果表明,中引式气力输送随着操作气速的变化,管内灰栓的流动模式也相应发生变化,分别为：柱塞流、栓流和悬浮流;柱塞流压力频谱较小,灰栓、气栓相间的多栓流属基本稳定流动;栓流压力频谱振幅最大,易成为独栓,属不稳定流动,输送量与柱塞流相当;悬浮流压力频谱最低,属稳定流动,输送量最低,输送速度最快,管道易磨损．柱塞流、栓流及悬浮流模式,对于给定物料操作气速与输送平均压力之间随着操作气速增加,输送压力逐渐下降．     

浅谈重力场对气固流态化的影响

气固并流顺重力场与逆重力场流动形成了迥然不同的流态化机制.与提升管相比,下行床具有气固速度及颗粒浓度径向分布较均匀、气固停留时间短而一致等特点,其流型更接近平推流.     

T型流道平缝模中的溶体流动分析及流道尺寸设计

通过对广泛应用于挤塑生产的T型流道平缝模结构的研究，对熔体在T型流道中的流动均匀性和停留时间进行了分析，并依此提出了流道尺寸设计的可变模唇长度，可变模唇间隙和带有调节排的结构设计方法。     

X70钢在淡水中的腐蚀行为研究

利用极化曲线技术、电化学阻抗测试技术研究了X70钢在淡水中的腐蚀行为.实验结果表明,水温和流速对X70钢腐蚀的影响显著.随着温度的增加,X70钢的腐蚀速率也增加,X70钢在40℃的河水中腐蚀速度约为25℃时的3倍.用磁力搅拌器,人为造成水的流动状态,实验结果发现,X70钢在流动河水中的腐蚀速率大于静止河水,而且随着水的流速度的增加,X70钢的腐蚀速度增加.     

连铸过程中注流吸氧速率估算

根据传输理论建立注流吸氧理论模型，从而定量计算连铸中大包到中间包注流吸氧速率。结合生产试验数据对理论模型计算的结果进行讨论。计算结果表明，注流的吸氧速率随着空气中氧分压增加而增加，随着注流半径增加而增加；注速、注流高度增加都会使注流的吸氧速率增加。     

T91钢管在冷轧过程中开裂的原因分析

通过显微组织及工艺分析发现,T91钢管在生产过程中发生开裂的原因与冷轧过程中的中间退火热处理制度、热处理炉的温度均匀性有关.要减少T91钢的开裂,可对冷轧后的钢管进行及时、充分的中间退火处理.     

回注水中乳化油对储层伤害的实验研究

回注水中的乳化油进入渗透率不同的储层时会对储层造成吸附和液锁等不同程度的伤害.以某油田S区块中高渗油藏为例,基于采出液中乳化油含量分析结果,通过岩心流动实验,研究3种含油量的乳化油溶液侵入不同渗透率级别的人造岩心时对其造成的损伤,并分析注入速度对其结果的影响.结果表明:注入速度的影响较小;随着岩心渗透率增大,乳化油溶液...     

基于电阻层析成像技术的弹状流实验研究

在气液两相流研究中,相分布、相速度等流场特征信息对深入了解流动机理、提高模型计算精度有重要意义,但由于气液流动的复杂性与随机性,使得它们的准确测量较为困难。该研究基于快速电阻层析成像技术,首先对垂直向上气液管流中弹状流流型下多种工况的流动结构进行图像数据采集与重建;然后通过互相关算法得到轴向速度场分布,并与漂移流模型进行对比;再对按时序排列的横截面图像序列进行调整得到正确比例的空间三维图像;最后获得段塞长度、频率等特征信息。结果表明,快速电阻层析成像技术可以测得速度场分布、段塞长度、频率等特征信息,可用于优化与这些参数相关的理论模型和经验关系式,有助于提高气液两相流的模型计算精度。     

Area method analysis and thermodynamic behavior of nonmetallic micro-inclusions in casting slab of GCr15 bearing steel

The distribution and characteristics of nonmetallic micro-inclusions of GCrI5 bearing steel were explored through metallographic area method in virtue of tracer method and electronic microscope.The results show that the micro-inclusions,of which the average value is 0.032%,are mainly the compounds formed via the adsorption/aggregation of multielement deoxidized compounds and secondarily deoxidized products on tundish liquid level.The micro-inclusions of diameters from 0 to 5 μm are 92.5% in total,which basically determines the characteristics of inclusions distribution in casting slab.The inclusions of diameters more than 10 μm only account for less than 1% in total,which have little influence on steel quality.The relationship between equilibrium compositions of the first deoxidation products and molten steel compositions was also calculated based on thermodynamic theory.     

连铸生产GCr15轴承钢工艺的改进

针对连铸生产GCr15轴承钢出现的质量问题,将过热度、结晶器水流量、二冷比水量、电磁搅拌等工艺参数进行调整。调整后生产的GCr15轴承钢过程中,钢水的可浇性得到了改进,避免中间包发生冻钢事故,防止铸坯产生矫直裂纹,产品的低倍合格率明显提高,带状组织100％合格,质量明显提高。     

RH和RH-KTB精炼过程中钢液流动和混合特性的研究

The flow and mixing characteristics of molten steel during the vacuum circulation refining,including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrastahl-Heraeus-Kawasaki top blowing) processes,were investigated on a 1/5 linear scale water model of a 90t multifunction RH degasser,The circulation rate was directly and more accurately determined,using a new method by which the more reliable results can be obtained.The fluid flow pattern and flow field in the ladle were demonstrated,observed and analyzed.The mixing time of liquid in the ladle was measured using electrical conductivity method.The residence time distribution in the RH model was obtained by tracer response technique.The influence of the main technological and geometric factors,including the gas top blowing*(KTB) operation,was examined.The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula:Q1p=0.0333Qg^0.26Du^0.69Dd^0.80(t/min),where Qg-the lifting gas flow rate(NL/min);Du and Dd-the inner diameters of the up and down-snorkels(cm),respectively.The maximum value of circulation rate of molten steel in the case of the 30cm diameters either of the up-and down-snorkels for the RH degasser(the “Saturated” rate) is approximately 31 t/min.the corresponding gas flow rate is 900NL/min.Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing charateristics of the RH process under the conditions of the present work.There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process.A liquidliquid two-phase flow is formed between the descnding stream from the down-snorkel and the liquid around the stream.All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining.The correlation between the mixing time and the stirring energy density is τmε^0.50 for the RH degasser.The mixing time rapidly shortens with an increase in the lifting gas flowrate.At a same gas flow rate,the mixing times with the up-and down-snorkel diameters either of 6 and 7cm are essentially same.The 30cm diameters either of the up-and down-snorkels for the RH degasser would be reasonalble.The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser.     

不锈钢铝合金半固态连接工艺参数研究

By using semisolid joining technique,the bonding of stainless steel and semisolid aluminum alloy is successfully realized.The relationships between interracial shear strength and solid fraction of aluminum alloy,bonding pressure and time of keeping pressure were studied by the method of orthogonal experiment.The interfacial structure and the fracture structure of the bonding plate are studied by means of optical microscope (OM) and scanning electron microscope (SEM).The results show that there is the best solid fraction between the solid phase line and the liquid phase line of the semisolid aluminum alloy,with the increase of bonding pressure and pressure time,the interfacial shear strength increases rapidly,and then with further increase of bonding pressure and pressure time,the shear strength rises little.Along the interface,solid phase and liquid phase bond with stainless steel by turns because of the different diffusion ability.So,a new type of non-equilibrium diffusion interfacial structure is constructed at the interface of stainless steel and aluminum alloy,compound mechanism of plastic and brittle fracture interface was formed at the shear fracture interface.     

轴承钢EAF-LF-VD-CC生产工艺的优化与实践

本钢特殊钢公司轴承钢连铸坯生产初期,钢材质量低倍检验合格率低,消耗指标高,冶炼周期长。通过电弧炉配入40%铁水、采用炉门氧枪及炉壁氧气喷吹系统配合供氧的操作模式;优化LF精炼渣、中包保护渣、结晶器保护渣成分及操作工艺,使轴承钢质量低倍合格率明显提高,GCr15钢的化学成分全部达到本钢制定的标准要求,其中〔O〕=8～10×10-6、其它检验项目均满足GB/T18254-2002标准要求,GCr15钢实物质量已经达到国内先进水平。     

多层交错桁架钢结构住宅的设计分析

国内多层钢结构住宅体系尚处于探索阶段.通过对一多层交错桁架钢结构住宅建筑工程的设计分析,介绍了该结构的设计方法、受力特点及适用性,表明交错桁架钢结构应用于多层住宅是一种值得推广的结构体系.     

基于欧拉方法的机翼表面水滴撞击特性数值模拟

基于欧拉方法分析了不同飞行速度和不同气象条件下NACA0012机翼水滴撞击的特性,使用Fluent商用软件计算空气流场,并通过UDS模块求解水滴相控制方程。从计算结果分析得出:局部水滴收集系数及水滴撞击范围随飞行速度和平均水滴容积直径的增加而明显增加;液态水含量对水滴撞击特性影响不大。     

45#钢螺栓表面线状缺陷分析

针对45#钢螺栓表面线状缺陷进行了低倍、金相、电子探针等检测分析,结果表明,线状缺陷由大型夹渣造成,其主要成分为SiO2、CaO、Al2O3、Na2O,系连铸过程中酸性钢水中包覆盖剂卷入所致。     

单片微型计算机液位测量系统设计

精确地对压力容器内部液体液位,易燃易爆液体液位的测量,是现代测量科学的重要课题.本文设计一种利用单片微型计算机与光纤传感器组成的液位测量系统,它利用液面对光纤入射光和反射光原理实现对液位的测量,使用频分复用技术分别取出多个传感器的输出信号,并同时可以增大测量的安全性.文中详细论述了液位信息检测、电路处理的原理,给出了整体电路设计框图和软件流程.实验结果表明,系统液位测量范围为10cm～300cm,具有较高的测量精度.