共查询到18条相似文献,搜索用时 140 毫秒
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针对某厂连铸机浇注亚包晶钢板坯表面纵裂纹发生率较高的问题,分析了双侧孔浸入式水口对裂纹形成的影响。在此基础上对浸入式水口结构进行优化,开发了新型浸入式水口。通过模拟研究和生产应用分析,对比了双侧孔浸入式水口与新型浸入式水口结构的差异以及两者对结晶器内流场和温度场的影响。结果表明,采用双侧孔水口浇注时,结晶器钢液流场和温度场分布不合理,导致结晶器内液渣层厚度不均匀,尤其是水口与结晶器壁之间位置液渣层厚度偏薄,从而诱发了板坯表面纵裂纹缺陷的大量发生,纵裂纹集中在板坯宽面中心400 mm范围,裂纹长度50~1 200 mm,深度2~12 mm;采用新型浸入式水口更有利于水口与结晶器壁间钢液流动,增加水口出入口钢液束流能力,使结晶器内钢液流场对称、温度场分布均匀、液渣层厚度均匀增加,亚包晶钢板坯表面纵裂纹改善显著,表面纵裂纹发生率由10.9%降低至1.5%。 相似文献
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板坯连铸结晶器浸入式水口工艺参数的模拟正交试验 总被引:3,自引:0,他引:3
利用流场计算机软件PHOENICS 3.4建立的三维有限差分模型模拟邯钢 16 2 4mm× 2 2 8mm板坯连铸结晶器内钢液的流场和温度场 ,并采用正交试验方法对影响钢液流动的主要因素 :水口浸入深度、倾角、水口内径和侧孔截面积进行研究和分析。结果表明 ,水口浸入深度和倾角对冲击点温度指标和液面卷渣指标影响显著。该板坯连铸结晶器浸入式水口最佳工艺参数为 :浸入深度 12 0mm ,倾角 15° ,内径 6 3 75mm ,侧孔截面积 6 0mm× 6 5mm。 相似文献
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以国内某钢厂220 mm×1800 mm板坯连铸结晶器为原型,根据相似性原理建立相似比为0.6的水模型,利用粒子图像测速技术(PIV)对比不同浸入式水口(SEN)的出口角度、浸入深度及水口底部结构条件下的结晶器内流场流速特征,同时使用波高仪对液面波动振幅进行实时监测,并结合F数分析各SEN条件对结晶器内钢液流动特征.研究发现,在各浸入式水口条件下,位于结晶器液面1/4宽面处附近出现矢量流速向下的剪切流,同时在水口附近发现不规则漩涡.试验结果表明:浸入式水口的出口角度、浸入深度的增加能够强化上回旋区缓冲作用,降低结晶器液面表面流速;尽管凹底结构SEN能减弱钢液湍动能,但其对1/4宽面处剪切流速度的影响不大.另外,液面波动幅度和F数变化规律一致,且当浸入式水口出口角度15°、20°,浸入深度135 mm、145 mm条件下波幅与F数最为合理,从而减小或避免液面卷渣,提高连铸坯质量. 相似文献
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Mehmet Metin Yavuz 《国际钢铁研究》2011,82(7):809-818
Computational fluid dynamics (CFD) model with magneto hydro dynamics (MHD) is developed for a thin slab caster to investigate the effects of electromagnetic brake (EMBr) on liquid steel flow in continuous casting mold and to determine the EMBr practices which lead to optimal flow structure. Particle Image Velocimetry (PIV) tests in water model and meniscus flow measurements in real caster are performed to validate the predictions obtained with CFD models. The performance of different submerged entry nozzle designs, SEN 1 and SEN 2, are evaluated. The effects of nozzle submergence in relation to the applied magnetic field on mold flow structure are quantified. There are significant differences between flow structures obtained with SEN 1 and SEN 2, even though both designs have fundamental similarities and contain four ports. EMBr mainly reduces the meniscus velocities for SEN 2 as opposed to the foremost influence of EMBr for SEN 1 that is to significantly slow down the downward jet coming from the bottom ports. In addition, reducing the EMBr strength for shallow nozzle submergence and increasing the EMBr strength for deep nozzle submergence help to maintain similar meniscus activity for all conditions. 相似文献
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以鞍山钢铁集团公司中薄板坯连铸机为研究对象,利用商业软件CFX44对结晶器内钢水流场和传热凝固进行了数值模拟,主要研究了三孔浸入式水口的冶金特征及其对结晶器内钢水流场和温度场的影响。结果表明,采用三孔浸入式水口可以优化结晶器内钢水流场和温度场,稳定坯壳发育和成形,防止拉漏。 相似文献
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Thomas Wondrak Sven Eckert Gunter Gerbeth Konrad Klotsche Frank Stefani Klaus Timmel Anthony J. Peyton Natasa Terzija Wuliang Yin 《Metallurgical and Materials Transactions B》2011,42(6):1201-1210
This article describes experiments on the combined determination of the distribution of liquid metal and argon in the submerged
entry nozzle (SEN) and of the flow in the mold of a small-scale physical model of a continuous slab caster. For visualizing
the metal distribution in the SEN, mutual inductance tomography (MIT) is applied, while the flow in the mold is determined
by contactless inductive flow tomography (CIFT). The results of the latter are validated in part by ultrasonic Doppler velocimetry
(UDV). Accompanying measurements provide information about the levels in the tundish and in the mold, as well as on the pressure
in the SEN. Depending on the gas flow rate, various flow regimes are identified, among them pressure and mold level oscillations,
transitions between double and single vortex flows, and transient single port ejections. 相似文献
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Baokuan Li Toshimitsu Okane Takateru Umeda 《Metallurgical and Materials Transactions B》2001,32(6):1053-1066
Biased flow occurs frequently in the slab continuous casting process and leads to downgraded steel quality. A mathematical
model has been developed to analyze the three-dimensional biased flow phenomena associated with the effects of static magnetic-field
application and argon gas injection in the slab continuous casting process. By moving the submerged entry nozzle (SEN) from
center to off-center, the biased flow and vortexing flow in the mold can be reproduced in the numerical simulation. The existence
of a vortexing flow is shown to result from three-dimensional biased flow in the mold. A vortex is located at the low-velocity
side adjacent to the SEN. The vortex strength depends on the local horizontal velocity of molten steel and decreases gradually
with distance from the free surface. The vortexing-zone size depends on the biased distance of the SEN, and the intensity
of the vortexing flow depends on the casting speed of the continuous caster. Only when the location and strength of the magnetic
field are properly chosen, can the vortexing flow be suppressed by a static magnetic-field application. The effect of argon
gas injection on the vortexing flow is not remarkable. The combination of magnetic-field application and argon gas injection
can correct the biased flow and suppress the vortexing flow by suppressing the surface velocity and removing the downward
velocity near the SEN in the mold. 相似文献
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Effect of EMBr on Flow in Slab Continuous Casting Mold and Evaluation Using Nail Dipping Measurement
The nail dipping method was developed to investigate the effect of electromagnetic brake on the mold top surface flow in a certain slab caster with different casting speed and submerged entry nozzle (SEN) depth. The shape of the meniscus profile and direction of flow were quantified by analyzing the angular profile of the lump for each solidified nail, and the error evaluation for the nail dipping measurement was also determined. The results show that the meniscus level fluctuates with time variation; the electromagnetic force suppresses the high‐speed flow and decreases the meniscus flow velocity, which makes the meniscus level flatter and slower. A stronger meniscus velocity and fluctuation were created by increasing casting speed and decreasing the SEN depth. Furthermore, the effect of magnetic field on the fluid flow in the mold has been investigated. 相似文献
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LIFENG ZHANG SUBO YANG KAIKE CAI JIYING LI XIAOGUANG WAN BRIAN G. THOMAS 《Metallurgical and Materials Transactions B》2007,38(1):63-83
Fluid flow in the mold region of the continuous slab caster at Panzhihua Steel is investigated with 0.6-scale water model
experiments, industrial measurements, and numerical simulations. In the water model, multiphase fluid flow in the submerged
entry nozzle (SEN) and the mold with gas injection is investigated. Top surface level fluctuations, pressure at the jet impingement
point, and the flow pattern in the mold are measured with changing submergence depth, SEN geometry, mold width, water flow
rate, and argon gas flow rate. In the industrial investigation, the top surface shape and slag thickness are measured, and
steel cleanliness including inclusions and the total oxygen (TO) content are quantified and analyzed, comparing the old and
new nozzle designs. Three kinds of fluid flow pattern are observed in the SEN: “bubbly flow,” “annular flow,” and an intermediate
critical flow structure. The annular flow structure induces detrimental asymmetrical flow and worse level fluctuations in
the mold. The SEN flow structure depends on the liquid flow rate, the gas flow rate, and the liquid height in the tundish.
The gas flow rate should be decreased at low casting speed in order to maintain stable bubbly flow, which produces desirable
symmetrical flow. Two main flow patterns are observed in the mold: single roll and double roll. The single-roll flow pattern
is generated by large gas injection, small SEN submergence depth, and low casting speed. To maintain a stable double-roll
flow pattern, which is often optimal, the argon should be kept safely below a critical level. The chosen optimal nozzle had
45-mm inner bore diameter, downward 15 deg port angle, 2.27 port-to-bore area ratio, and a recessed bottom. The pointed-bottom
SEN generates smaller level fluctuations at the meniscus, larger impingement pressure, deeper impingement, and more inclusion
entrapment in the strand than the recess-bottom SEN. Mass balances of inclusions in the steel slag from slag and slab measurements
show that around 20 pct of the alumina inclusions are removed from the steel into the mold slag. However, entrainment of the
mold slag itself is a critical problem. Inclusions in the steel slabs increase twofold during ladle changes and tenfold during
the start and end of a sequence. All of the findings in the current study are important for controlling slag entrainment. 相似文献