【作者】 赵磊；

【导师】 李胜利；

【作者基本信息】 辽宁科技大学 ， 材料加工工程， 2012， 硕士

【摘要】 目前国内大型水电站闸门、核电站建设等大型钢构件仍依靠进口,在对其进行研制和开发中首要任务是优质大型钢锭的生产。强冷生产特厚扁钢锭是一种改善特厚扁钢锭质量,提高其生产效率的新工艺。本论文采用数学模拟和物理模拟实验相结合的方法,研究了不同强冷条件下钢锭凝固行为,可以为特厚扁钢锭的生产提供理论基础和实践指导。根据相似理论,采用硫代硫酸钠纯溶液代替钢液进行了钢的冷态模拟物理实验,实验发现随着冷却强度的改变模型的坯壳厚度、凝固时间、缩孔的凝固位置等都发生了变化,实验结果验证了强冷工艺的可行性。用PRO-E建模软件对60T扁钢锭进行了三维实体造型,建立钢锭凝固传热数学模型,利用ProCAST软件对金属充型凝固过程进行了仿真模拟计算。通过对钢锭凝固过程中的温度分布、热流密度分布、疏松缩孔的位置及凝固时间的分析表明,冷却强度增加钢锭的凝固时间减少,缩孔位置提高,但由于钢锭模传热的限制,与风冷相比,水冷增加冷却强度的效果不明显。风冷与空冷相比凝固时间缩短了3.5h,缩孔位置提高但体积没有减小。采用上部空冷、下部风冷的“梯次”强冷比空冷冷却时钢锭的全凝时间减少了2.7h,钢锭中心缩孔的位置上升60cm,缩孔体积减少8000 cm3。对硫代硫酸钠的凝固过程进行了数学模拟研究。对比发现数学模拟曲线与物理模拟凝固进程随时间变化曲线拟合较好,两者所体现的凝固进程变化趋势相同,说明数学模拟的参数设定以及模型合理,数值模拟结果可靠。更多还原

【Abstract】 In this paper, a special method of intensive cooling outside mold has been presented to produce huge rectangular ingot. The solidification and heat transfer of a 60t huge rectangular ingot has been simulated by mathematical simulation and physical simulation experiment combination of methods in this paper.Firstly,In a physical model designed by using similitude theory, the steel solidification progress were simulated by using Na2S203.5H20, and the growth of crystal structure, the final solidification location were observed. Physical simulation result verify the feasibility of strong cold process.Secondly, establishing the three-dimensional entity mold by pro/e software and ingot solidification heat-transfer mathematic model, and it has been the simulation calculation by ProCAST software. Through the solidification time, the temperature distribution, heat flux distribution and the position of loose and shrinkage show the feasibility of strong cold process.The results of the study show that the solidification times of ingot body was shortened by increasing the cooling intensity and the position of loose and shrinkage of ingot was higher by increasing the cooling intensity. Compared with air cooling, the solidification time of wind cooling shorten the 3.5 h, the shrinkage of the position higher but do not reduce the volume; Because of the heat transfer ingot mold restrictions, compared with wind cooling, the effect of water cooling is not obvious. So this paper hold out "gradient" cooling .It is that the upper of ingot mold is air cooling and the bottom of ingot mold is wind cooling .Compared with air cooling, at the "gradient" cooling the solidification times of ingot body reduces 2.7 h, the position of loose and shrinkage of ingot rise 60 cm and shrinkage cavity volume reduces 8000 cm3.Mathematical simulation and physical simulation experiment results tell us that by intensive cooling, the solidification time of the can be obviously shortened, internal soundness can be ensured and the surface quality could be improved.更多还原