钢包釉对钢中总氧含量及夹杂的影响研究

炼钢过程中出钢后钢渣附着在钢包工作衬壁上,形成钢包釉,对钢-耐火材料的反应产生重要影响,是钢中夹杂的主要来源之一,同时对钢中总氧含量也产生影响.本文通过设计不同钙硅比的钢包釉层,研究其对钢中总氧含量及夹杂物的影响.研究发现:铝镁质耐火材料与钢水直接接触时,耐火材料组分溶解进钢水中形成夹杂,增加了钢中的夹杂和总氧含量;耐火材料表面覆盖釉层时,耐火材料与钢水通过界面层间接反应,减少了钢中的夹杂和总氧含量.其中钙硅比高的界面层,钢中总氧含量低,夹杂的数量也少,但是夹杂的尺寸较大.     

洁净钢生产用钢包内衬的改进

研究了洁净不锈钢生产用浇铸钢包内衬的改进。首先,为了改善低碳含量的MgO—C砖的抗热震性,分别对碳质材料的种类以及添加剂的含量进行了研究。研究发现,通过使用膨胀石墨、细石墨和炭黑并且减少金属添加剂的含量,可以改善材料的抗热震性。区域试验表明,将研制的低碳MgO—C砖用于渣线部位,钢中增碳量降低。此外,对于白云石碳砖防止氧化物夹杂的产生进行了研究。白云石碳砖用于钢水区域,钢中氧化物夹杂降低。     

镁质耐火材料与钢中镁铝尖晶石夹杂形成的热力学关系

洁净钢用耐火材料已越来越受到人们的关注,耐火材料是钢中氧化物夹杂的主要来源之一.为了考察耐火材料对钢中氧含量的影响,将纯铁置于镁质浇注料坩埚中在还原气氛下于1600℃温度保温3h.对试验后的钢样进行了SEM和EDS分析,结果发现钢中有MgO·Al2O3夹杂形成.本文从热力学的角度对试验过程中熔钢里形成的尖晶石氧化物的成因进行了分析,计算结果表明:即使钢中的Al含量较低,MgO·Al2O3尖晶石依然可以形成.     

优质镁钙砖在AOD精炼炉上的应用

目前 ,AOD炉用耐火材料大体分为镁铬砖、镁白云石砖(镁钙砖 )及白云石砖 3种。欧洲的AOD炉衬普遍采用煅烧白云石砖 ,日本的AOD炉大多数仍采用MgO -Cr2 O3 砖 ,也有的采用综合砌筑 :风眼区 10层以下使用MgO -Cr2 O3 砖 ,前墙、炉底及其他部位使用MgO -CaO砖。太钢 18tAOD炉建成初期 ,炉衬全部使用镁铬砖。随着镁钙质材料的开发 ,在风眼区以外的部位逐步推广使用镁钙砖 ,风眼区一直使用电熔半再结合镁铬砖。这样的材料选择和综合砌筑方法一直延续到2 0 0 0年。随着AOD的扩容改造和单渣法精炼工艺的推行 ,MgO -Cr2 O3 砖区的侵蚀…     

石墨对MgO-C耐火材料导电性能的影响

用w (C)为 97%、粒度分别 >0 .147mm和 <0 .147mm的两种石墨研究了石墨的加入量(5 %～ 2 0 %)和粒度对MgO -C砖导电性能的影响。通过扫描电镜和光学显微镜分析等手段 ,对MgO -C砖的导电机理进行了探讨 ,并提出了导电模型。结果表明 :石墨的加入量是影响MgO -C砖导电性的关键因素 ;当石墨加入量为 2 0 %时 ,MgO-C砖的电阻率为 0 .39× 10 - 4Ω·m ,低于国内外有关资料报道的数据 ;选用粒度 <0 .147mm的石墨时 ,MgO -C砖的电阻率较低。     

沥青涂覆镁砂对MgO-C质底吹供气元件抗热震性的影响

为了提高顶底复吹转炉用MgO -C质底吹供气元件的使用寿命 ,研究了沥青涂覆量和沥青涂覆镁砂颗粒添加量对MgO -C砖性能的影响。结果表明 ,添加沥青涂覆镁砂颗粒能明显改善MgO -C砖的抗热震性能 ,同时在保证合理的体积密度、显气孔率和强度的基础上 ,得出了能够提高供气元件抗热震性能的合理配比方案为 :沥青涂覆量为 3% ,沥青涂覆镁砂和电熔镁砂的质量比为 1 1。MgO -C砖抗热震性能提高的原因是由于高温下沥青涂覆镁砂中的沥青炭化而在镁砂颗粒周围形成缝隙 ,这些缝隙能吸收和消除较多的变形能量     

耐火材料对IF钢总氧含量及夹杂的影响

研究了石英 -刚玉质、刚玉质和镁质耐火材料对所处理的IF钢总氧含量和夹杂的影响 ,用氧测定仪对钢中的总氧含量进行了测定 ,并对钢中的夹杂进行了SEM和EDS分析。结果表明 :耐火材料对钢的增氧量的大小与所用耐火材料的氧潜能指数 (IOP)有关 ,IOP越大 ,增氧量越大 ;镁质耐火材料由于有较低的IOP ,所以对钢水的增氧和夹杂的影响最小     

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.     

X60管线钢硫化夹杂物钙处理技术研究

在对管线钢中硫化物的作用综合分析的基础上,依据冶金热力学原理,结合莱钢生产实践,分析计算了X60管线钢硫化物的钙处理工艺条件,并对莱钢牛产的管线钢中的夹杂物进行了检测分析.结果表明,莱钢生产管线钢时,大部分炉次精炼终点氧含量高于理论计算得到的钙处理所需的目标氧含量3.42×10-6,钢中钙含量未达到理论计算得到的钙硫平衡时所需的钢中溶解钙含量,硫化物夹杂物变性并不完全,钢中存在MnS,MnS-CaS复合夹杂物.     

防堵塞浸入式水口的使用

叙述了防堵塞浸入式水口的使用情况,对用后残砖分析表明以CaZrO3-C材料制作的浸入式水口,在浇注08Al钢时,有较好的使用效果,可实现多炉连浇。防堵塞效果主要取决于钢液中析出的Al2O3与防堵塞料的反应产物和钢水温度。     

不锈钢冶炼用铁水包Al2O3-SiC-C内衬砖的性能与侵蚀机理

铁水包内衬材料长期服役于间隔周期较长的高、低温交替环境,极易发生剥落与侵蚀损毁。为了探索影响铁水包内衬材料使用寿命的主要因素,对市面上四种铁水包Al₂O₃-SiC-C内衬砖的化学成分、物相组成、物理性能和微观结构进行了分析,并以高炉渣为侵蚀介质,重点研究了不锈钢冶炼用铁水包Al₂O₃-SiC-C内衬砖的侵蚀机理。结果表明:铁水包Al₂O₃-SiC-C内衬砖中Al₂O₃含量越高,高温下制品的液相量越低,越有利于提高耐火砖的高温力学性能;随着含碳量的增加,铁水包Al₂O₃-SiC-C内衬砖的抗渣性得到明显改善,但抗氧化性及高温抗折强度呈下降趋势;高炉渣中CaO、MgO向耐火砖中渗透,与耐火砖中的Al₂O₃、SiO₂发生反应形成高熔点的镁铝尖晶石及低熔点的钙长石等,生成的低熔相会加剧耐火砖的侵蚀。     

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     

精炼钢包渣线镁碳砖被侵蚀的显微分析

通过静态和动态抗渣实验,考查了精炼钢包用渣线镁碳砖被侵蚀的情况,并从显微分析的角度研究了镁碳砖被侵蚀的原因.研究表明,在静态实验中,镁碳砖中的氧化镁会溶解到熔渣中去,方镁石晶粒间的杂质在高温下形成低熔相成为熔渣侵入的通道并促进了该溶解过程.在动态实验中,由于镁碳砖中的石墨会溶解到钢水中,位于钢水和熔渣界面的熔渣进而渗透到镁碳砖中,加上钢水的冲刷等因素造成镁碳砖的损毁.     

Multifunctional Refractory-lined Vessel: Ladle Aggregate

A ladle primarily is a container used to transport molten steel from the steelmaking unit to the casting facility.The essential requirements are heat resistant,insulative and strong enough to hold molten steel up to 300 t,with a structure of multilayered refractory lining in a steel shell vessel.When a ladle is assembled with three-phase graphite electrodes,a ladle furnace forms,starting steel refining process with/without the vacuum tank degasser and RH circulating degasser,in order to meet the growing demand on high purity and higher quality steel.The working lining is under aggressive conditions that comprise the chemical reaction with molten steel,the severe corrosion of liquid slag,the disaggregation through oxidation,and the strong stress due to the impacting of the melts and gases and the effects of thermomechanical behaviors.Magnesiacarbon brick is one of the major materials,being indispensable for the slagline of a ladle furnace.Alumina-magnesiacarbon brick has played an important role to substantially increase the service life in the metal zone,from the early lining materials of high alumina and doloma bricks.The permanent lining must assume sufficient responsibility to allow finishing the process of the engaged charge in case of a failure in the working lining.The insulation layer must be as thin as possible in order to maximize the ladle’s capacity,and reduce the shell temperature for saving energy.In this issue,several integrant refractories are reviewed or investigated in order to compile a lining overview,and to contribute a prolonged service life under aggressive working conditions of the ladle furnace.     

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.     

IF钢生产用耐火材料的技术发展

概述了耐火材料在IF钢生产技术中的作用、应用状况和技术发展,并着眼于IF钢生产中最为关注的因耐火材料造成的钢水增碳、增氧和夹杂物缺陷等问题,论述与之相关的钢包内衬、连铸及中间包精炼和结晶器冶金中耐火材料的应用和开发方面所采取的应对策略和措施.     

250 t钢包底吹氩卷渣和钢液裸露的模拟

针对某钢厂250 t钢包底吹氩气过程进行水模型实验和数值模拟,考察了吹气量和渣层厚度对卷渣行为和吹气量、渣层厚度及透气砖透气性能对钢液裸露面的影响,分析了卷渣形成机理. 结果表明,吹气量对卷渣形成具有决定性作用,吹气量控制在0.96 m3/h(对应实际流量69 m3/h)以下可避免卷渣;随着吹气量的增加,钢液裸露面积逐渐增大,当吹气量达到0.70 m3/h时,钢液裸露面积百分比约达14%,继续增大吹气量,其增加幅度变缓;随着渣层厚度的增加,临界卷渣吹气量和钢液裸露面积逐渐减小,以37 mm(对应实际渣厚150 mm)厚渣层覆盖,可有效防止钢液二次氧化;透气砖堵塞对钢液裸露面积影响较大,顶部钢液形成两不同大小的裸露亮圈,并加重对包壁耐材的冲刷与侵蚀,降低钢的洁净度. 工艺优化后,钢包水口结瘤率降低至0.1%以下,且可降低生产成本.     

EFFECT OF MOLTEN ALUMINUM ON VARIOUS REFRACTORY BRICK*

To study the effect of molten aluminum on refractory brick with a view toward explaining some of the brick failures in aluminum melting furnaces, the following test was conducted. Brick of different compositions and from various manufacturers were placed on end in the bottom of an electrically heated ladle to which molten aluminum was added. After holding the molten aluminum in contact with the brick for thirty-five days, it was poured out and the ladle was allowed to cool slowly to room temperature. A study of the brick revealed that some failed by penetration of the aluminum into the brick accompanied by a reaction between the aluminum and the brick. This penetration was less with the denser brick than with the more porous ones. Of the brick tested, there was the least reaction between aluminum and the chrome brick and most between aluminum and silica brick. Many other factors, however, must be considered when deciding which brick is the most economical to use in aluminum melting.     

微膨胀高铝砖的生产与应用

采用优质高铝矾土和莫来石合成料为主要原料,添加蓝晶石、红柱石、硅线石(简称三石)和叶蜡石等作膨胀剂,使用软质黏土作结合剂,再外加适量添加剂,经适宜温度焙烧制成高铝砖,并成功应用于冶炼低碳钢、不锈钢等钢包内村。该砖在高温区使用时产生微膨胀,使钢包内衬具有良好的整体性,从而提高抗侵蚀性。     

Effect of magnesia-calcium hexaaluminate refractories on the quality of low-carbon alloy steel

High-performance alloy steel is distinguished by its purity. Inclusion contamination and oxygen addition to the steel due to long contact between the refractories of the tundish and the steel should be avoided. In this study, the static crucible method was used in the interaction experiments between MgO–CA₆ composite and low carbon alloy steel. The effects of different proportions of MgO–CA₆ on the content of alloying elements in steel were analyzed. Morphology, quantity, size, and distribution of inclusions were also examined. The results indicated that more inclusions (e.g., MnO, FeO, and MnS) were generated between the MgO material and alloy elements (e.g., Fe and Mn) in molten steel. The oxygen content in molten steel of CA₆, MgO–0.28CA₆, and MgO–0.70CA₆ materials, as well as the number of inclusions, were sharply reduced. The particle size was smaller, resulting in good molten steel purification ability. The oxygen content of the steel in contact with the MgO–0.28CA₆ material was relatively low, characterized by a reduction in the proportion of inclusion area and particle.