【作者】 陈永金；

【导师】 彭其春；

【作者基本信息】 武汉科技大学 ， 钢铁冶金， 2009， 硕士

【摘要】 RH作为炼钢与连铸之间的重要精炼设备之一,能很大程度上提高钢水质量,满足大批量生产高附加值产品的要求。为保证RH的正常运行,顺利实施RH单联工艺,实现产品的高质低耗,充分发挥投资效益,对RH本身及相关工艺技术的研究与开发则是涟钢重要的技术改造项目。本文以涟钢RH单联工艺为研究对象,结合RH有关理论分析,对RH相关工艺技术进行了调查研究,采用数理统计等分析方法,系统研究了RH-MFB工艺过程的脱碳、脱氮、温度控制、合金化和钢水纯净度等,分析了相关工艺参数对这些因素的影响,获得了适合涟钢RH-MFB工艺生产的技术参数并用以指导现场生产,达到了预期的效果。为此,本文主要得出如下结论:(1)为满足RH生产要求,转炉出钢碳控制在0.04~0.07%内,自由氧控制在0.08%以下,出钢温度控制在1680~1700℃左右。因此,需提高转炉操作水平,提高一倒命中率;(2)为获得最佳脱碳效果,处理时,尽量消除压降平台,控制合理的吹氩流量,选择适宜的供氧参数等,使处理后碳含量稳定在0.003%以下;(3)通过提高真空度、利用真空下的碳氧反应、提高氩气流量等措施,使钢中氮含量由进RH时的35.9×10-6降至24.6×10-6,平均脱氮率为31.5%;(4)在精炼开始阶段的5~10min内钢包内钢液温降较大。实际生产过程中大部分炉次的加铝量基本与计算值一致,但因测温时刻、热滞后等众多因素的影响致使加铝升温的计算值与实际升温值差异较大。RH合适的出站温度控制在1580~1590℃;(5)Mn收得率波动较大,平均收得率为96.06%。通过调整锰铁合金的加入时机即在加完铝块后2~3min加入、及时清理料仓口等,可进一步提高Mn的收得率;(6)经RH-MFB真空处理后,钢中全氧去除率为90.23%(参考值),脱氮率为31.5%。通过严格控制转炉下渣量、提高钢包渣吸附夹杂的能力、改善长水口氩气密封效果等措施,以进一步降低钢水中T[O],减轻钢液的吸氮现象;(7)RH-MFB精炼后,钢液中大于10μm的显微夹杂数量明显减少,且显微夹杂物尺寸较精炼前也有所减小,从而提高了钢水质量;(8)基体为Al2O3的夹杂物是RH精炼过程中存在的主要夹杂物,其形貌特征各异,在工艺后期多以球状、细小块状存在。出RH时,钢中大型夹杂物的数量为14.32mg/10kg,主要以SiO2、硅酸盐和TiO2类夹杂为主。更多还原

【Abstract】 As one of the important refining equipments between steelmaking and continuous casting, RH can improve steel quality largely and meet the demand of mass production of high additional value. To ensure operation of RH regularly, conduct the single-link process smoothly, realize the high quality and low consumption and bring investment benefit into full play, researching and developing on RH and related process are important the technical innovation project of Liansteel.By taking the single-link process of RH in Liansteel as the research object, combining with the relevant theoretical analysis, investigation researching on RH related process and using the methods of mathematical statistics, decarburization, denitrogenation, temperature control, alloying and steel cleanliness were researched systematically in RH-MFB process. And yet, the influence of the related processing parameters to these factors were analyzed and the suitable technical parameters of RH-MFB process production in Liansteel were obtained to guide the on-spot work. Finally, the anticipated effect was achieved. Therefore, the main conclusion were as follows:(1)In order to meet the requirements of the production of RH, the tapping-carbon in converter was controlled in the range of 0.04~0.07%, the free oxygen was controlled below 0.08% and the tapping temperature was about 1680~1700℃. Thus, it was should be improved the operational level of BOF converter and the direct hit rate;(2)To maximize decarburization, eliminating pressure drop platform as possible, controlling reasonable argon flow and choosing suitable oxygen blowing parameters during treatment made the outlet carbon content was steady below 0.003%;(3)The nitrogen content in steel was 35.9×10-6 when entering into RH and 24.6×10-6 in the out station, and yet the nitrogen removal efficiency was 31.5% by taking some measures such as improving vacuum degree, carbon oxygen reaction under vacuum and increasing argon flow;(4)The temperature drop was obvious in 5~10min at the beginning of refining. The feeding amount of aluminum of most heats in practical production process was basically identical with the calculated values, but the values of Al addition for heating and the practical temperature rising made a great difference in that the influence of factors such as the temperature measurement time, thermal hysteresis and so on. The proper tapping temperature of RH should be controlled in the level of 1580~1590℃;(5)The yielding rate of Mn had a larger fluctuation and the average yield was 96.06%. It was could further improve the yielding rate through adjusting the addition opportunity namely adding ferromanganese in the after of 2~3min when added aluminum block, disposing the bunker promptly and so on;(6)After RH-MFB vacuum treatment, the total oxygen removal rate is 90.23%(reference value) and the denitrogenation rate is 31.5%. To reduce T[O] in steel furtherly and alleviate nitrogen absorption phenomenon of steel, the measures such as controlling tapping slag amount of converter strictly, improving absorbing inclusion capability of ladle slag, improving argen sealing effect of long nozzle were implemented;(7)The micro inclusion amount of the larger than 10μm in liquid steel was decreased significantly and the size in comparison with before refining became smaller after RH-MFB refining. And in consequence, the quality of molten steel was improved;(8)Matrix was aluminum oxide inclusion as the main micro inclusions in liquid steel during RH-MFB refining process, which had dissimilar characteristics of the shape and appearance. Especially, the micro morphology of aluminum oxide inclusion existed mainly as spherical and clumpy in late process. The quantity of large inclusions was 14.32mg/10kg in the steel when leaves RH and the large inclusions was mainly by SiO2, silicate and TiO2.更多还原