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Process stability in the thin strip casting process of steel has been investigated with a laboratory pilot caster. Depending on the steel grade and the process parameters irregular process states could be observed. It has been proved experimentally that the observed behaviour is not caused by the regulation system. Investigations of microsections on the cast strips have shown evidence of periodical changes in heat flux during solidification and strip formation as the reason for observed oscillating process variables. Similar to conventional flat rolling forward and backward slip between strip and casting rolls during the joining of the shells can occur. Under certain combinations the process parameters and the cast material a backward‐slip can lead to local lift‐offs of the solidified shells. This circumstance significantly disturbs the heat flux and consequently the solidification, even periodically. 相似文献
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不锈钢是双辊薄带连铸工艺重点开发的钢种之一.综述了不锈钢的分类和性能特点,简要介绍了不锈钢的几种生产型式,详细讨论了双辊薄带连铸生产不锈钢的技术要点和难点. 相似文献
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In thin strip casting of steel surface cracks may occur; it was analysed which influencing parameters are important and how the cracks can be avoided. The studies, mainly with C60‐steel, lead to the following results: the cracks are formed during the casting process under high temperatures; on the strip surface hot and colder areas occur, and the cracks have to be studied in both areas separately; mostly transverse cracks are formed; the crack density depends on roll material, ‐ force, ‐ roughness, ‐ surface layers; the cracks are initiated by a temperature break down and by rolling within the pool range. 相似文献
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依据相似性原理采用1[∶]1比例搭建双辊薄带铸轧水模型试验平台,研究了不同铸速对铸轧熔池流动规律的影响,并建立低雷诺数的湍流数学模型,对熔池内流场和温度场分布规律进行分析。研究结果表明,由于液体的黏性力和轧辊的挤压作用,在熔池芯部区域会产生回流现象。芯部回流可在一定程度上搅动熔池并促使芯部温度降低,有利于促使温度场和溶质场均匀稳定。研究还表明,随着铸轧速度的增加,回流区位置下移且回流区面积增大,回流作用增强。但过大的铸轧速度反而会使液面波动加剧、Kiss点位置过低等问题产生,从而影响产品质量。 相似文献
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结晶辊内部结构非常复杂,受热发生变形后,辊表面形状变得不规则,因此研究结晶辊温度场、热应力及热变形,掌握其分布规律,对于控制结晶辊的变形,得到均匀的铸带具有重要意义.以结晶辊为主要研究对象,采用热结构直接耦合方法计算结晶辊的温度场、热应力和热变形,为结晶辊的设计提供参考.结果表明,选用Be-Co-Cu作为结晶辊材质,辊转动30 s后,辊外表面温度和最大等效应力保持稳定,最高和最低温度分别为198和449℃,最大等效应力为1041 MPa;转动300 s后,辊内部温度及变形达到稳定状态,辊外表面径向位移都在0.4~0.5mm之间.通过对比Be-Co-Cu材质和钢材质的温度和最大等效应力,得出Be-Co-Cu材质更适合于制造双辊的结论. 相似文献
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利用非线性热力耦合有限元方法,对浇铸过程中结晶辊辊套的温度场分布进行了研究,并同时计算出了结晶辊的热变形.给出了浇铸稳定阶段的结晶辊温度场分布和热变形规律;分析了浇铸速度对结晶辊温度场和热变形的影响.通过分析得出,在浇铸稳定阶段结晶辊温度只在表层区域发生周期性变化,内部保持基本稳定,浇铸速度越低,周期性变化幅度越大. 相似文献
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WANG Chengquan YE Changhong ZHANG Yujun YU Yan FANG Yuan 《Baosteel Technical Research》2019,13(2):32-38
In the strip-casting process,the surface topography of the casting roll has a significant influence on the solidification microstructure and surface quality of the as-cast strip. Shot-blasting treatment is an important way to achieve a suitable surface topography on the casting roll. In this study,a casting roll of beryllium copper alloy was shot blasted using steel pellets in the laboratory,resulting in a randomly distributed discontinuous peak and dent surface topography,in which cold deformation-slip bands and fine-deformation twins were formed. The thickness of the deformed copper alloy was about 100 μm during the shot-blasting process,and the copper hardness value increased significantly within 40 μm of the surface,with a maximum increase of more than 20% compared to the mean substrate hardness value. Within 60-100 μm of the surface,the hardness at the peak position was still higher than the copper substrate mean value,but the hardness at the dents was not,which was mainly due to the copper alloy slip and twinning deformation mechanisms. The surface hardness was similar to that of the substrate after the shot-blasted sample had been subjected to thermal shock. The molten steel first chilled and nucleated at the surface peaks of the casting roll;furthermore,fine dendrites grew and crossed over the middle of the dents. Therefore,the peak intervals of the shot-blasted surface are an important factor in solidification quality control. 相似文献
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The numerical model for the solidification process of metal in the twin-roll type strip caster is presented in this paper. In the model the temperature change as well as the eliminating process of latent heat is calculated along the stream lines obtained by a comparatively simple velocity field. The calculations are carried out on the strip casting of type 304 stainless steel under various casting parameters. The results so obtained show a good fit to the experimental ones, and suggest that the control of the height of molten pool is of importance to the establishment of the optimal operation. 相似文献
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A transient heat-transfer model (STRIP1D) has been developed to simulate the single-roll continuous strip-casting process. The model predicts temperature in the solidifying strip coupled with heat transfer in the rotating wheel, using an explicit finite difference procedure. The model has been calibrated using strip thickness data from a test caster at ARMCO Inc. (Middletown, OH) and verified with a range of other available measurements. The strip/wheel interface contact resistance and heat transfer were investigated in particular, and an empirical formula to calculate this heat-transfer coefficient as a function of contact time was obtained. Wheel temperature and final strip thickness are investigated as a function of casting speed, liquid steel pool depth, superheat, coatings on the wheel hot surface, strip detachment point, wheel wall thickness, and wheel material. 相似文献
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《钢铁冶炼》2013,40(5):374-378
AbstractAn experimental study with respect to the influence of electric current pulse (ECP) on the solidification structure of molten silicon steel was investigated with a copper mould designed to simulate the twin roll casting process. The experimental results showed that the application of ECP can increase the proportion of equiaxed grains up to 67·5%. The mechanism of exerting ECP is also discussed. It can be confirmed that the application of ECP on twin roll casting could effectively improve the solidification structure of silicon steel strip. 相似文献
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《钢铁冶炼》2013,40(1):75-80
AbstractTwin roll strip casting is regarded as a prospective technology offering many economic benefits. The control of fluid flow in the pool is, however, particularly difficult due to the high casting speed and small pool volume. In the present study, a three-dimensional mathematical model has been developed for the coupled analysis of fluid flow, heat transfer and solidification in the pool using the finite difference method. The characteristics of transport phenomena in the pool of a twin roll strip caster using a wedge type melt delivery system were analysed by numerical simulation. The results show that it is desirable for the wedge melt delivery system to provide the uniformity of flow and temperature in the pool to maintain the casting process and improve the strip quality. 相似文献
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Jordan Pavlossoglou 《国际钢铁研究》1981,52(4):153-158
Development of a mathematical model of the thermal process and flowchart of simulation. Application of the model to start of rolling when the rolls have a homogeneous temperature and to rolls having a temperature profile brought about during the previous revolution. Interpretation of the results in terms of design parameters of a strip rolling mill. Application of the model for estimating physical constants. Further development. 相似文献
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摘要:研究了退火温度对双辊薄带连铸Si质量分数为3.2%的高强度无取向硅钢组织、织构和性能的影响。结果表明,700℃保温时试验钢开始发生再结晶;800℃保温时,试验钢已完全再结晶,平均晶粒尺寸为26.4μm;900和1000℃保温时,试验钢中的晶粒开始逐渐长大,平均晶粒尺寸分别长大到33.8和40.9μm,且900℃退火时晶粒组织最均匀。随着退火温度的升高,试验钢中有利织构组分λ织构逐渐增强,Goss织构则在900℃退火时强度最强。因此,试验钢在900℃退火时有利于兼顾磁性能和力学性能。 相似文献
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《钢铁冶炼》2013,40(5):347-358
AbstractThe important functions promoted by powdered flux added over the liquid steel surface in continuous casting moulds are strongly affected by the thickness of the liquid layer that forms as a result of the heat absorbed. The present work discusses the results of a three-dimensional steady state model, developed to represent the coupled fluid flow and heat transfer phenomena that determine thickness profiles of the liquid flux layer. Since the laminar flow of the liquid slag layer depends on the shearing imposed on it by the turbulent motion of the liquid steel beneath it, and since additionally this motion is strongly influenced by the flow characteristics of the steel stream poured into the mould through the submerged entry nozzle (SEN), separate turbulent flow models for the liquid steel in the SEN and the mould were also developed. The consistency among the models and their accuracy was judged by comparing thickness and temperature flux profiles measured in plant against predicted ones; the comparison showed good agreement. The effects of casting speed, mould width, and flux viscosity and heat of melting on the liquid layer thickness were investigated. The last variable was found to exert the most marked influence. Different from conventional casting moulds, where the liquid layer thickness increases with increasing casting speed, in compact strip process moulds the thickness remains almost constant with increasing casting speed. This difference is well accounted for by the model, which suggests that this behaviour stems from the different slag flow patterns generated in straight, wide moulds and in thin moulds having a central upper funnel shaped section. 相似文献