太钢耐酸管线钢洁净度控制技术研究

发布时间：2018-04-18 20:28

  本文选题：管线钢 + 夹杂物　； 参考：《北京科技大学》2017年博士论文

【摘要】：抗酸管线钢主要用于输送含有H2S等酸性介质的石油和天然气。其特殊的使用环境,需要管线钢有非常稳定的高性能。通过设计冶炼工艺路线,采用超低硫冶炼技术可以有效控制A类夹杂物。但条串状CaO-Al_2O_3夹杂物的控制却一直是国内外管线钢冶炼的难点,同时,此类夹杂物严重影响管线钢的抗氢致裂纹性能(即HIC性能)。传统工艺强调采用钙处理工艺进行夹杂物改性,但如何精细化控制CaO-Al_2O_3系列夹杂物的研究并不多。太钢公司是中石油等企业所使用耐酸管线钢的主要制造单位之一。本文针对太钢耐酸管线钢的冶炼工艺流程,系统分析了各项工艺控制参数的作用,并针对铁水预处理工序、精炼工序,管线钢硫含量、钙含量和夹杂物类型分别进行了分析。同时对钙处理后的钙含量变化、夹杂物变化、夹杂物变性处理等方面进行了研究。通过在太钢实际生产条件下的研究结果表明,在低硫冶炼工艺条件下,高碱度强还原性精炼渣和钢液之间发生了反应。钢中夹杂物按照MnO和SiO2→Al_2O_3→CaO-Al_2O_3-MgO→CaO-Al_2O_3-CaS 的顺序转变。在钙处理过程中,随着钙含量提高,夹杂物中的CaS、CaO含量增加,同时Al_2O_3含量减少,并最终在铸坯中形成簇群状CaO-Al_2O_3-CaS、CaS-CaO等类型的复合夹杂物。研究结果表明,在硅钙线质量不变、冶炼成分控制相对稳定的情况下,适宜的硅钙线喂入量决定了夹杂物形态,硅钙线喂入量不足或过量都容易导致钢材产品的质量问题。在研究夹杂物转变的基础上,本课题分别对LF精炼过程、RH精炼过程、钙处理过程及连铸过程中的夹杂物转变进行了热力学讨论,形成了热力学模型。结合前人对钙处理工艺的研究,根据相关的热力学和动力学数据,建立了钙处理过程中钢包流场模型、钙的汽化模型以及夹杂物转变反应模型。通过CFX流体计算软件将三个模型进行耦合计算,分别计算了 RH软吹过程钢包流场特点,钙处理过程中钙含量变化以及夹杂物变化过程。模拟计算钙处理过程中钙含量变化与实测数据基本一致。模拟计算钙处理过程钢中各类夹杂物浓度变化以及类型与实际试验炉次数据基本一致。依据模型计算结果,将硅钙线的喂入量由400m/炉(0.51 1Kg/t钢)调整为 600m/炉钢(0.767Kg/t 钢)。根据以上研究,分析清楚了夹杂物在不同工艺过程中的变化。通过模型计算,确定了实际生产中硅钙线的喂入量参数,较为准确的控制钢中夹杂物形态,管线钢质量的受控程度得到很大提高,有效控制了 HIC的发生。同时为太钢不锈钢等品种钢的纯净度控制提供了思路,提高了太钢产品竞争力。
[Abstract]:Acid-resistant pipeline steel is mainly used to transport oil and natural gas containing H 2S and other acid medium.Its special use environment, need pipeline steel has very stable high performance.Class A inclusions can be effectively controlled by using ultra-low sulfur smelting technology through the design of smelting process.However, the control of strip CaO-Al_2O_3 inclusions has always been a difficult point in pipeline steel smelting at home and abroad. At the same time, such inclusions seriously affect the hydrogen-induced crack resistance of pipeline steels (i.e. HIC properties).The traditional process emphasizes on the modification of inclusions by calcium treatment process, but there are few studies on how to control the CaO-Al_2O_3 series inclusions finely.TISCO is one of the main manufacturing units of acid-resistant pipeline steel used by PetroChina and other enterprises.Aiming at the smelting process of acid resistant pipeline steel of Taiyuan Iron and Steel Co. Ltd, this paper systematically analyzes the effect of various process control parameters, and analyzes the sulfur content, calcium content and inclusion type of hot metal pretreatment process, refining process, pipeline steel sulfur content, calcium content and inclusion type respectively.At the same time, the changes of calcium content, inclusions and inclusions denaturation after calcium treatment were studied.Under the actual production conditions of TISCO, the results show that under the condition of low sulfur smelting process, the reaction between high alkalinity and strong reduction refining slag and molten steel has taken place.The inclusions in the steel are transformed according to the order of MnO and SiO2 Al_2O_3 CaO-Al_2O_3-MgO CaO-Al_2O_3-CaS.In the process of calcium treatment, with the increase of calcium content, the content of CaSn-CaO in inclusions increases, while the content of Al_2O_3 decreases. Finally, a cluster of CaO-Al2O3-CaS2O3-CaS-CaO inclusions are formed in the castings.The results show that under the condition that the quality of calcium silicon wire is constant and the smelting composition is relatively stable, the proper feeding quantity of calcium silicon wire determines the shape of inclusions, and the insufficient or excessive feeding quantity of calcium silicon wire will easily lead to the quality problems of steel products.Based on the study of inclusion transformation, the inclusion transformation in LF refining process, calcium treatment process and continuous casting process were discussed respectively, and a thermodynamic model was formed.According to the thermodynamic and kinetic data, the flow field model of ladle, the vaporization model of calcium and the reaction model of inclusion transformation in the process of calcium treatment were established.By coupling the three models with CFX fluid calculation software, the characteristics of ladle flow field during RH soft blowing process, the change of calcium content and the variation of inclusions in the process of calcium treatment were calculated respectively.The variation of calcium content in the process of simulated calcium treatment is basically consistent with the measured data.The variation of inclusion concentration and the type of inclusions in the steel during calcium treatment are basically consistent with the experimental data.According to the results of model calculation, the feed rate of calcium silicate wire was adjusted from 0.51 1Kg/t steel of 400m/ furnace to 0.767kg / t steel of 600m/ furnace steel.According to the above research, the changes of inclusions in different processes are analyzed.Through the model calculation, the feeding parameters of silica calcium wire in actual production are determined, the inclusion shape in steel is controlled accurately, the quality of pipeline steel is greatly improved, and the occurrence of HIC is effectively controlled.At the same time, it provides ideas for purity control of stainless steel and so on, and improves the competitiveness of products.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TF764

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