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《Baosteel Technical Research》2010,(Z1):91
This article is try to explain or analyze the key technologies of controlling the surface quality of low carbon steel as cast strip through investigation of interface heat transfer between solidified shell and liquid steel.The one of the key technologies of controlling surface quality of low carbon steel as cast strip is through the casting roll surface texture in order to achieve the homogeneous solidification on the casting roll.Another is through forming a thin film on the casting roll surface in order to achieve a balance between rapid solidification and homogeneous solidification.This film formed between the twin roll and the molten steel can be controlled by adjusting the chemical composition and inclusion in liquid steel through controlling the amount of all[O]and free[O]. 相似文献
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《钢铁冶炼》2013,40(4):310-316
AbstractAn unequal diameter (1 : 3), two roll thin strip casting machine has been designed and fabricated for investigation of the direct casting of thin strip on a laboratory scale. The system consists of a preheatable shallow tundish with online heating facility, water cooled rotating rolls (chill and auxiliary) for solidification of the liquid metal, and a stripper assembly. The machine has a variable speed. Roll gap setting and roll pressure adjustment are two important features of the machine. It is also possible to vary the placement angle of the auxiliary roll with respect to the chill roll. A heat transfer model was developed, based on experimental casting results. Experiments were conducted using AISI 304 grade stainless steel. Up to 100 kg of steel was cast without interruption into strips of widths 100 and 200 mm and thickness varying between 1 and 2 mm. Some of the process parameters affecting the quality of the strip were identified. 相似文献
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Tacke K.-H. 《钢铁冶炼》2013,40(4):317-323
AbstractStrip casting of low carbon steels has been investigated using a laboratory twin roll machine with copper rolls. The following grades have been studied: a deep drawing low carbon (LC) steel, a LC steel with titanium addition, and a high strength low alloy (HSLA) grade. The casting behaviour of these steels has been examined, and the observed surface defects classified. Defects are most pronounced for the LC grade and significantly less for the HSLA steel and the LC steel with titanium addition. The as cast structure has been analysed. It can be modified by post-cast treatment, e.g. by normalisation or in line rolling. The mechanical properties of cold rolled and annealed strip materials and their textures are presented. Satisfactory sheet properties can be achieved both as hot band and as cold rolled sheet when adequate treatment steps are applied. Consequences for strip casting applications and future research are discussed. 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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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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硅钢是双辊薄带连铸工艺最具开发潜力的钢种之一。综述了国内外双辊薄带连铸工艺生产硅钢技术的现状,并讨论了该工艺的技术要点、难点以及研究和发展的方向。 相似文献
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LI Jie Jian-Hong MA Yu-Lai GAO Qi-jie ZHAI 《钢铁研究学报(英文版)》2009,16(6):7-12
A new approach of applying the Electric Current Pulse (ECP) with parallel electrodes to promotion of the transition from columnar to equiaxed crystals and improvement of macrosegregation was introduced. And the experiments of application of ECP in the different stage of solidification have been carried out. The results show that applying ECP in both the initial and the late stage of solidification can promote the columnar to equiaxed transition (CET). Analysis shows that during solidification application of ECP induce a large number of nuclei around the upper surface, which subsequently showers down into the melt and impinges growth front of the columnar crystal. Therefore the CET occurs. In addition, this method is also employed to influence the solidification processing of bearing steel, the results show that the structrue is changed from columnar to equaixed, indicating that ECP can enhance the homogeneity of structure and composition of bearing steel. 相似文献
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Columnar to Equiaxed Transition During Solidification of Small Ingot by Using Electric Current Pulse
A new approach to applying the electric current pulse (ECP)with parallel electrodes to the promotion of the transition from columnar crystal to equiaxed crystal and the improvement of macrosegregation was introduced. The ECP was applied to different stages of the solidification. The results showed that the application of the ECP in both the initial stage (the thickness of solidified shell reached 2 mm approximately)and the late stage (the thickness of solidified shell reached 14 mm approximately)of solidification can promote the columnar to equiaxed transition (CET). The analysis showed that during solidification, a large number of nuclei around the upper surface fell off due to ECP, which subsequently showered on the melt and impinged the growth front of the columnar crystal. There-fore, the CET occurred. In addition, this method was also employed to influence the solidification process of bearing steel, and the results showed that the structure was changed from columnar crystal to equiaxed crystal, indicating that ECP can enhance the homogeneity of structure and composition of bearing steel. 相似文献
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A three‐dimensional mathematical model has been developed to simulate turbulent fluid flow, heat transfer and solidification in the pool of a twin‐roll strip caster. A Darcy‐porosity approach was used to study the fluid flow within the mushy solidification zone in the pool. The effect of the heat transfer coefficient and permeability constant on the flow and solidification was also predicted. It was shown that an even flow and temperature distribution of the pool can be obtained by using a suitable feeding system. The heat transfer between the rolls and the solidifying metal has a big influence on the location of the solidification end point. The permeability of the mushy zone is a key factor which affects the flow and solidification in the twin‐roll strip casting process. 相似文献
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Strips (1.6?mm thick) of Fe–6.5wt-%Si alloy were prepared by twin roll casting. The microstructure was found to be mainly columnar and equiaxed grains. The plastic deformation of the strip is inhomogeneous in the thickness direction. The most serious deformation is located at a certain depth from the strip surface. The influence of mechanical factors on the solidification structure of the strip is discussed. As the two solidifying shells contact with each other at the end of solidification, the columnar growth fronts break into fragments, which finally grow into equiaxed grains. At the hot rolling stage, the inhomogeneous deformation of the strip is attributed to the fact that the ductility of the alloy is sensitive to temperature. There is a large temperature gradient in the thickness direction, which can be up to 510°C?mm??1. 相似文献
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特种合金双辊薄带连铸生产技术进展 总被引:1,自引:0,他引:1
双辊薄带连铸技术(TRC)已发展到产业化的初级阶段,如日本新日铁、德国Eurostrip、美国Castrip、韩国Postrip等公司的薄带连铸生产能力已达30~50万t/a,多炉连浇时间超过10h。介绍了多种特种合金,如髙硅电工钢(w(Si)为4.5%~6.5%)、高速钢、Invar合金、Inconel合金、TWIP钢等可用双辊薄带连铸,一次性形成毫米级薄带。由于高速冷凝,晶粒细化,成分偏析极少,生产成本低,成材率高,TRC是当前双辊薄带连铸产业化的新途径之一。 相似文献
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The homogeneity of as‐cast structures is essential to the application of advanced steel materials. The relationship between as‐cast equiaxed grain structure and homogeneity was examined by means of OPA (Original Position Analysis) technology. The results indicate that macrosegregation of the solute elements was obviously suppressed in silicon steel billets with equiaxed grain structure. Furthermore, two methods to achieve an equiaxed grain structure were described. One is to use titanium‐based inoculation technology. TiN particles and TiN/ Ti2O3 complex particles can precipitate at the early stage of solidification and then play an important role of heterogeneous nucleation when the solidification condition is carefully controlled. The other method is to maintain a small temperature gradient in the mould to enhance the constitutional undercooling As a result, the as‐cast equiaxed grain structure was well developed in the experimental billets. 相似文献
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《钢铁冶炼》2013,40(6):497-502
AbstractAn analytical model has been developed to investigate the optimum pinch roll load and resulting slab thickness reduction during the continuous casting of a steel, constant thickness, thin slab in a vertical type machine. The pinch roll unit consists of two driven pinch roll sets, which support the solidified hot slab weight and take up the reaction forces owing to slab bending. Optimum conditions prevail when the pinch roll load required to support the slab weight is equally shared by the two pinch roll sets and has the minimum value allowing proper control of the slab speed. The model has been validated by being applied to an existing industrial case of thin slab continuous casting of plain low carbon steel. The effects of pinch roll radius, slab thickness, casting speed, slab temperature and the material carbon percentage on minimum pinch roll load and slab thickness reduction ratio have been investigated. Expressions have been obtained for the optimum pinch roll load and slab thickness reduction ratio related to the prevailing process parameters, which the plant operator can directly apply to determine the optimum pressure setting for the hydraulic cylinders fitted to the movable roll ends. The bending roll load is shown to be small compared with the pinch roll load. 相似文献