【作者】 常江；

【导师】 赵红阳； 胡小东；

【作者基本信息】 辽宁科技大学 ， 材料科学与工程， 2021， 硕士

【摘要】 模铸技术是钢锭生产的传统工艺,由于在解决特殊品种合金、特殊钢材时具有连铸技术无法比拟的优势,在特钢领域中仍广泛使用模铸技术。本课题的背景是国内某特钢厂进行生产设备的改造升级,需要设计新钢锭与设备相匹配。由于特钢厂所生产的钢锭主要是由后续的轧制成材,因而对锭型与锭模进行设计优化时除了考虑断面尺寸、模锭比、锥度、帽容比等,还需要考虑轧机和轧制工艺的因素,包括有轧辊的最大开口度、孔型宽度、孔型数量、压下量和辊身宽度等,以及轧机前后的翻钢装置、轧机夹床、均热炉大小等多方面的影响。因此,本文从铸造凝固和轧制变形两个方面来综合考虑钢锭的设计及其优化。本文根据要求分别设计大中小三种锭型,分别为3.2t方锭、4.8t方锭、8.4t矩形锭。其中8.4t矩形大钢锭的设计比较困难,其难点在于必须考虑轧机的限制因素。目前的研究中轧机往往是考虑不充分的地方,由于大钢锭的断面尺寸大,因此轧机需要大开口度和大变形轧制时的强力轧辊和大电机。对设计的大中小三种钢锭利用solidworks软件建立三维几何模型;通过Any Casting软件模拟不同参数下钢锭的浇注与凝固过程,分析钢锭凝固过程中心温度场和凝固后的内部缺陷;进而利用Deform模拟8.4t大钢锭的第一道次轧制变形,分析孔型侧壁是否起夹持作用及其对轧制稳定性的影响,并验证钢锭设计的合理性。研究结果表明,3.2t方锭凝固过程中,帽口保温能力较好,内部缺陷较少,产品符合生产质量要求,设计合理;4.8t方锭凝固过程中帽口补缩能力不足,缺陷位于钢锭中心处影响最终产品质量,需要进行优化;分别对锥度和断面形状进行优化,本体锥度调高到3.5%与5%后内部质量皆有所提升,但是5%锥度时全凝时间延长0.29h,因此3.5%锥度更为合理;用5.6t矩形锭取代4.8t方锭后效果最佳,凝固后内部缺陷几乎消失;8.4t矩形锭凝固趋势与5.6t矩形锭相似,且凝固后内部缺陷同样良好,说明小型、大型与优化后的中型钢锭设计都较为合理,可以保证产品质量,并且矩形锭在凝固时结果优于方锭。根据轧制模拟的结果,大钢锭前几道次选择宽度大的孔型轧制后,应快速进入到后续的第二三孔轧制,且轧件表面设计成具有凸度的形状更加合理。更多还原

【Abstract】 Mold casting is a traditional process for steel ingot production.Although there are disadvantages such as low yield rate,large loss of steel ingot molds,and many internal defects of steel ingot,mold casting is still widely used in special steelindustry due to the incomparable advantages over continuous casting in handling special alloys and heavy steel ingot.The production equipment of a domestic special steel plant is undergoing transformation and upgrading,therefor it is required to design new ingots to match the equipment.Since the steel ingots produced by special steel plant are to be rolled subsequently,in addition to the section size,mold-ingot ratio,taper,and cap-ingot ratio,it is also necessary to consider the rolling process while designing and optimizing the ingot shape and ingot mold,such as the maximum roll opening,roll pass width,number of roll pass,rolling reduction,roller mill width,the steel turning device before and after the rolling mill,the rolling mill bed,and the size of the soaking furnace,etc.In this paper,three types of ingots were designed according to the requirement:large,medium and small.The design of large ingots was difficult due to the limitation of rolling mills,which is usually not fully considered in the current research.Due to the large section size of the large ingot,a powerful rolling mill with large openings and large deformation and a large motor were required.The 3.2t square ingot,4.8t square ingot,and 8.4t rectangular ingot were modeled by Solidworks.The pouring and solidification process of steel ingots under different parameters were simulated by Any Casting to analyze the central temperature field during the steel ingot solidification process and the internal defects after solidification.The first rolling process of the 8.4t large steel ingot which is difficult to achieve was simulated by Deform and a more reasonable first roll pass was selected to verify the rationality.The results show that during the solidification process of the 3.2t square ingot,the casting head is well capable in heat preservation,and the internal defects are less.The rolled products meet the production quality requirements and the design is reasonable;during the solidification process of the 4.8t square ingot,the feeding ability of the casting head is poor,and the defects locates in the center of the steel ingot,which affects the quality of the final product and the design should be optimized;the taper and section shape are optimized separately,and the internal quality is increased after the taper is increased to 3.5% and 5%,but the total setting time is extended by 0.29 h at 5% taper,so 3.5% taper is more reasonable;after replacing 4.8t square ingot with 5.6t rectangular ingot,the internal defects almost disappear after solidification;the solidification process of 8.4t rectangular ingot is similar to that of 5.6t rectangular ingot,and the internal defects are also less after solidification,indicating that the design of small,large and optimized medium-sized steel ingots are all reasonable,which can ensure product quality,and the result of rectangular ingots is better than square ingots.According to the results of the rolling simulation,it is appropriate to select roll pass with large width for the first pass;for the last few passes,it is better to select roll pass which is contact to the workpiece.In addition,the surface of the rolled piece with convex shape is more favorable to the rolling process.更多还原