超低碳铝硅镇静钢精炼过程中夹杂物的行为及其对钢组织的影响

针对RH精炼并结合典型的渣-钢化学平衡实验,研究了超低碳铝硅镇静钢精炼过程中夹杂物的变化以及钢包顶渣组成对钢中夹杂物的影响. 用激光共聚焦高温扫描显微镜在线观察了再加热过程中钢的微观组织变化,讨论了夹杂物对钢的晶粒长大的影响. 结果表明,本实验条件下精炼前钢中夹杂物是以Fe-Mn氧化物为主的复合夹杂,夹杂物数量和大小受渣碱度、Al2O3含量及CaO/Al2O3比值的影响较大,当碱度为1.5及Al2O3含量为20%时,夹杂物数量最少. 以成分优化的钢包渣与精炼末期钢样进行的平衡实验显示,夹杂物为Al2O3-MgO或Al2O3-MgO-SiO2-MnO为主的复合夹杂,随渣中w(MnO)的增加,复合夹杂中Mn含量有增加的趋势,使钢的晶粒长大过程需要更高的再加热温度. 钢样再加热后,钢中夹杂物变为以Al2O3, MgO, SiO2复合夹杂为主,三者总量占夹杂物总量的90%或以上,复合夹杂中MnO含量受加热制度影响.     

Nozzles for equipment for semicontinuous casting of stainless steels under synthetic slag

Summary The most aggressive influence is exerted by synthetic slag on aluminosilicate refractories, and the least — on zirconia and graphite-containing refractories.During the casting of steel under synthetic slag, high-alumina, zircon, and zirconia nozzles were cracked in the first minutes of operation and did not insulate the jet of metal from slag.Alumina-graphite, alumina-silicon carbide and alumina-graphite nozzles during the casting of steel did not crack, were only slightly eroded with slag and metal and provided normal working of the continuous casting plant.Alumina-graphite or alumina-graphite elongated nozzles are recommended for a unit used for the semicontinuous casting of titanium-containing steels involving synthetic slag.     

Testing ladle brick made by various factories

Conclusions The resistance of linings in steel-casting ladles depends on the working conditions and the construction of the lining, the quality of the brick laying during repairs of the working layer, and the resistance of the ladle brick. The greatest effect on the wear of the lining in ladles is exerted by the following working conditions: chemical composition of the slag, temperature of the metal being cast, the dwell time of metal and slag in the ladle during one casting, the height of the slag layer in the ladle, the thickness of the lining in each belt of the structure. The quality of the structure in the ladles is mainly determined by the size of the joints, the care with which they are filled with mortar, uniformity of drying and warming-up of the ladles before filling them with metal.The resistance of the ladle brick depends mainly on the apparent porosity and nature of the pores and the concentration of fluxes and mullite in the brick.The highest resistance in service was shown by Zaporozh'e ladle brick made from Polozhe kaolin and having the lowest apparent porosity. The concentration of iron oxides in the brick was moderate, and on average equalled 1.39%.In terms of falling resistance the ladle brick of the remaining concerns can be placed in the following order: Chasov-Yar, Semiluks, Bogdanovich, Magnitogorsk, and Borovich.In order to increase the resistance of steel casting ladle linings it is necessary to increase the resistance of the ladle brick by reducing the apparent porosity, using raw materials with low concentrations of fluxes and improving the firing in order to obtain the maximum conditions of the ladle, reducing to a minimum the quantity of slag and reducing the casting time; to use a more rational thickness for laying the ladles over the courses, taking into account better use of their capacity.Translated from Ogneupory, No.5, pp. 27–32, May, 1970.     

Effect of argon blow through a monoblock stopper in continuous casting of steel on the service of the stopper and nonmetallic inclusions in the cast steel

Kinetic equations of the dependence of the wear of corundum-graphite monoblock stoppers in the slag line and the head on the temperature of the steel in the intermediate ladle in continuous casting are derived as a result of a full-scale experiment. The equations make it possible to calculate the casting time at any possible temperature of casting with the use of corundum-graphite monoblock stoppers of a standard composition (TU 14-8-371-81). In addition to increasing substantially the number of casting cycles in a batch, argon blow through monoblock stoppers with porous inserts improves the quality parameters of cast steel ShKh-15 with respect to segregation bands, globules, central porosity, carbide segregation, content of sulfides and oxides, and subshrinkage segregation.     

60 t钢包浇注过程中汇流旋涡形成机理

依据相似原理,通过水模拟实验,对某钢厂60 t钢包浇注过程中钢水旋涡产生及卷渣过程进行研究,考察了初始液面高度、水口直径、水口偏心率和渣层对产生旋涡临界高度的影响. 结果表明,产生旋涡的临界高度随水口直径增大而增大,随水口偏心率增大而减小,初始液面高度对产生旋涡的临界高度影响不大,渣层在一定程度上可抑制旋涡的产生和发展,但其厚度对旋涡没有明显影响. 得到了钢包浇注过程中产生旋涡的临界高度h与钢包浇注水口直径d及水口偏心率e之间的关系式h=65.276+1.427d-76.778e.     

几种钢包用含碳耐火材料对IF钢增碳的比较

通过感应炉试验分析了钢包渣线用3种碳含量不同的镁碳砖(C的质量分数分别为8.3%、15.5%和17.9%),钢包底用蜡石-碳化硅砖(C的质量分数为3.71%)以及实验室开发的MgO-Al2O3-SiC质钢包渣线浇注料(C的质量分数为4.07%)对IF钢增碳的影响,并对其增碳的机理进行了初步分析讨论。试验结果表明:渣线镁碳砖的碳含量越高,对IF钢造成的增碳量越大;包底蜡石-碳化硅砖对IF钢水的增碳量达到渣线镁碳砖的7.73倍;MgO-Al2O3-SiC质浇注料也对IF钢产生明显的增碳效果,不宜用作冶炼超低碳钢的钢包渣线材料。     

ANS-OB钢包底吹排渣能力水力模型研究

ANS－OB是一种新的钢水炉外处理技术．在该工艺中，下罩前底吹排渣面积的大小直接影响着钢液处理的可靠性．本文采用水模的方法对110tANS—OB银包底吹Ar排渣能力进行了研究．结果表明，不同透气砖因底吹产生不同气液两相流结构，从而使其排渣能力有所不同．排渣效果受底吹流量和渣层厚度影响很大．对于110t钢包应将熔渣厚度控制在50mm以内，底吹流量上限为35Nm3／h即可满足ANS－OB对排渣效果的要求．     

RH真空处理过程中钢中氧含量预测模型

针对３００ｔ钢包ＲＨ真空处理低碳铝镇静钢的多次试验数据，建立了ＲＨ处理过程中钢中氧含量的定量预测模型，得到了钢中氧含量的预测公式模型综合考虑了纯脱气时间、真空室吹氩流量、钢水环流量、钢包渣中ＦｅＯ＋ＭｎＯ含量、钢包内衬材质等因素的影响，并对改进ＲＨ操作进行了讨论     

Refractories for the slide gates for molten steel

Conclusions A variety of refractories were subjected to testing in the slide gate of a 3-ton ladle. Nonoxygenous refractories are unsuitable for steel casting either because their thermal conductivity is too high or because they are not strong enough. Oxygen-containing materials developed cracks during the pouring operation so that they could be used only once.The refractories recommended for testing in a large-capacity ladle were periclase. corundum, and zircon types.The best results were obtained with periclase plates which permitted an entire melt to be poured within 1.5 h, during which the jet of molten steel was shut off 23 times.Translated from Ogneupory, No. 7, pp. 34–38, July, 1976.     

用后钢包透气砖显微结构分析

对60 t LF VD精炼钢包用刚玉-尖晶石透气砖和45 t LF精炼钢包用铬刚玉-尖晶石透气砖用后残砖进行了显微结构分析。结果表明:LF精炼工艺用透气砖狭缝及裂纹有明显的渣侵蚀和渗透,LF VD精炼工艺用透气砖狭缝和裂纹有钢液渗透。在周期性操作过程中,狭缝口部的扩大和热震造成的裂纹会使钢液或渣液的渗透侵蚀作用加剧并导致剥落现象的发生。透气砖狭缝堵塞直接影响吹通率和使用寿命,所以,要优化狭缝尺寸,提高材料的抗热震性。     

Steel contamination and growths on batching devices for continuous casting

Conclusions Delivery of metal with a closed jet facilitates a big reduction in the quantity of nonmetallic inclusions in the continuously cast ingot.By examining the kinetic rules governing the reaction of floating inclusions with circulation currents we established the optimum height of the molten steel level in the intermediate ladle as being equal to 600–650 mm.During the tightening of the nozzle, compounds enriched with alumina (highly dispersed refractory crystalline compounds of the corundum, mullite, and spinel type) are deposited on the walls of the channel.The higher the metal's concentration of inclusions containing large quantities of Al₂O₃, then the more intense is their bonding with the refractory, leading to tightening up and growth of the nozzle.Translated from Ogneupory, No. 8, pp. 22–27, August, 1970.     

铸钢用高通量复合水口的开发

随着铸钢工艺技术的发展,要求铸钢用水口在使用条件下具有安全可靠性和高的使用寿命。本实验通过研究不同材质铝碳、镁碳及尖晶石-碳的性能,成功地开发出高通量复合水口,它在大型钢包上使用后安全可靠、寿命高。     

Service of refractories in the continuous casting of 100 ton converter heats

Conclusions Refractories for steel-casting ladles used at present in the converter shop of the Novolipetsk Factory can be used for casting 100-ton heats. However, it is necessary to increase the resistance of the ladle linings.Ladle bricks, stopper tubes, and zircon nozzles provide reliable casting of 3–4 heats in series without replacing the intermediate ladle.To provide reliable covering of the jets where necessary it is recommended that use be made of highalumina plugs for intermediate ladle stoppers.Translated from Ogneupory, No. 7, pp. 37–41, July, 1968.     

Life of refractories at semi-continuous casting plant

Conclusions High-alumina, zircon, chamotte-kaolin, zirconia, and clay-graphite end nozzles were tested in a semi-continuous casting plant during the pouring of stainless steel in the pouring device, and SP-25 high-alumina and zircon nozzles were tested in the intermediate ladle.For use we recommend the high-alumina nozzles which are considerably cheaper than the zirconia ones.Zircon and high-alumina SP-25 nozzles do not erode when steel is poured from the intermediate ladle, they do not close up and can provide a stream of metal without splatter.     

矿渣种类及粉磨方式对性能的影响

钢铁冶炼过程的生产工艺造成矿物成分的差异，影响矿渣的易磨性；粉磨方式的差异造成矿渣活性的不同等等——所有这些对矿渣资源化的进程都会产生作用。矿渣资源化的深化才建材行业和钢铁工业都将产生重要和深远的影响，通过试验检测比较和分析了不同矿渣来源、不同粉磨方式的一些性能特征。     

Slag erosion-resistant coating for periclase-magnesia-aluminum spinel brick

The magnesia-carbon bricks are used at the ladle slag line adds carbon to molten steel and thus has an adverse effect on the smelting process. Steel production enterprises hope to remove carbon from the ladle slag line. This study presents a Silica sol (SS)–magnesium aluminate spinel(MA) coating that can be applied to the surfaces of periclase–MA spinel brick (spinel brick) to improve their slag erosion resistance, facilitating the elimination of carbon from the ladle slag line. The slag corrosion resistance mechanism of a spinel brick covered with the SS–MA coating was analyzed through scanning electron microscopy and simulation using FactSage software. The results show that increasing the SS content (C_SS) led to the formation of fine cracks during the coating-drying process and was detrimental to the slag erosion resistance of the coating. The optimum C_SS was 20%. In the high-temperature slag erosion experiment, the MA in the coating was capable of forming solid solutions with Fe and Mn in the slag, and the nano-SiO₂ in the coating interacted with the slag, increasing the viscosity of the slag and reducing its penetration. In addition, the presence of the coating extended the penetration path of the slag and reduced the contact area between the slag and the spinel brick and their chances to undergo chemical reactions, thereby protecting the spinel brick from slag erosion. The coated spinel bricks outperformed the magnesia-carbon brick in terms of slag erosion resistance, providing a basis for selecting carbon-free refractory materials for the ladle slag line.     

15-7PH不锈钢电渣重熔过程夹杂物的行为

为了明晰15-7PH沉淀硬化不锈钢中夹杂物的行为,进一步提高其洁净度,采用超高功率电弧炉初炼→AOD (Argon Oxygen Decarburization)脱碳→LF (Ladle Furnace)精炼→模铸工艺制备了自耗电极,并用带压摆控制的气体保护电渣重熔炉进行重熔。采用HORIBA氧氮氢气体分析仪检测了电渣重熔前后氧、氮等含量的变化;ASPEX扫描电镜分析了夹杂物的尺寸、数目、化学成分、形貌等。结果表明,电渣重熔后15-7PH不锈钢中氧、氮含量有轻微的下降,但夹杂物的组成变化不大,主要由氮化物夹杂物(氮化铝+氮化钛)、氮化物-氧化物复合夹杂物、氧化物夹杂物、硫化物-氧/氮化物夹杂物组成,其中氮化物夹杂物尺寸最大、数量最多,明显高于其他夹杂物。电渣重熔对夹杂物的数量、尺寸有明显影响。重熔后夹杂数量大幅增加,氮化物尤为明显,但大颗粒夹杂物明显减少。氮化物夹杂物大量存在的主要原因在于钢中存在较高的Al, Ti, N等元素,而电渣过程由于熔渣吸附、部分夹杂物溶解,使大颗粒夹杂物减少,重熔过程的快速冷却抑制了夹杂物长大,最终结果是夹杂物尺寸更细小,但数量增加。     

Characteristics and cementitious properties of ladle slag fines from steel production

Ladle slag is a by-product from further refining molten steel after coming out of a basic oxygen furnace (BOF) or an electric arc furnace (EAF). Air-cooled ladle slag has a very large portion of fine particles due to the conversion of β-C₂S to γ-C₂S during the cooling process. X-ray diffraction (XRD) analysis of three ladle slag fine samples passing 100, 200 and 325 mesh indicates that the major mineral in ladle slag fines is γ-C₂S, which does not show cementitious property in water. Experimental results have indicated that ladle slag fines show significant cementitious property in the presence of an alkaline activator. The finer the ladle slag is, the better the cementitious property of the slag is.     

Formation of ferrospinel layer at the corroded interface between Al2O3-spinel refractory and molten steel in RH refining ladle

Refining ladle is generally the last inclusion-removal vessel before the continuous casting of steel, so, it has a vital effect on the final steel quality. In this work, degradation process of a cement-free Al₂O₃-MgAl₂O₄ refractory in contact with molten steel/slag in the metal bath area of a Ruhrstahl Heraeus (RH) refining ladle was investigated. A reaction product layer with the formation of ferrospinel (hercynite) and Fe-rich phases was observed, suggesting that the interactions/reactions between the refractory lining and the molten steel should also be considered to have a better understanding of overall degradation mechanism of the refractory served under the RH refining conditions. The two types of alumina grains in the refractory, sintered and fused alumina, were attacked in an active way and a passive way, respectively. The effect of the crack generation and steel infiltration on degradation of the refractory was also discussed in detail, based on the microstructural characterizations.     

Service of zircon nozzles for continuous casting of converter steel

Conclusions In the continuous casting of converter steel without replacing the intermediate ladle between heats there is an increase in the resistance of the zircon nozzles. Wear somewhat increases with an increase in the number of heats from one to two, after which there is practically no change up to four heats.It became clear that an increase in the density of the zircon nozzles reduces their erosion.The nature of the erosion of zircon nozzles during continuous casting of converter steel does not alter, compared with the previously known character.With the use of zircon nozzles in the Red Army Silica Factory for rates 0.7 m/min, it is possible to cast without braking the jet of steel with the stopper.S. Z. Afonin, E. I. Ermolaeva, V. V. Parfenteva, V. D. Ryazantsev, and T. K. Chirkina took part in the work.Translated from Ogneupory, No. 1, pp. 20–23, January, 1968.