【作者】 雷加鹏；

【导师】 于学斌； 吴引淳；

【作者基本信息】 武汉科技大学 ， 钢铁冶金， 2004， 硕士

【摘要】 现代连铸生产普遍采用浸入式水口浇注技术。水口的结构参数与浇注工艺参数直接影响着结晶器内钢液的流场和温度场，进而决定了铸坯的表面质量和内部组织结构。因而，优化浸入式水口的结构参数和工艺参数意义重大。 本文以某钢厂大方坯结晶器为研究对象，基于相似原理建立了1：1的水模型，结合示踪剂法和摄影法等实验技术，对使用单孔、四孔、五孔和八孔SEN浇注时，无M—EMS和有M—EMS两种情况下结晶器内钢液的流场进行了模拟研究。得出以下结论： 1．在插入深度为h₁～h₂时，采用单孔喇叭型水口比采用单孔直筒型水口浇注时，冲击深度更浅，钢液在结晶器内温度和成分均匀化的效果更好，热中心更靠上，更有利于保护渣的熔化，可以获得高质量的铸坯。 2．原四孔SEN四个出孔不正交，导致结晶器内流场不对称，从内弧侧向外弧侧看，液面左后角和右前角均出现漩涡。原四孔SEN合理的浇注工艺参数应为：α=α₂～α₃，h=h₃±10mm。 3．五孔改进漏斗型SEN与原四孔SEN的情况相比，加大了冲击深度，不利于夹杂物的上浮。 4．采用设计的八孔SEN浇注时，即使h=h₅，液面波动仍达2mm，且液面上有漩涡形成，容易发生卷渣。 5．新四孔SEN最佳结构与工艺参数为：S=S₃，β=β₂，α=α＿3，h=h＿2±10mm。。将新四孔SEN、原四孔SEN和五孔改进型SEN各自最优结果进行比较，新四孔SEN的混均时间比后两者分别短了1Sec和0.54Sec，冲击深度变浅了19.7mm和31.4mm，上翻到液面时间缩短了0.92Sec和1.55Sec，液面波动几乎相同。 6．当液面流速在0.30～0.60m／s之间时，电磁搅拌强度是合理的。在本水模型实验中，输入功率为0.4～1.2W。考虑到结晶器为一连续式反应器，输入功率取范围的上限值1.2W。 7．启动M-EMS，采用原四孔SEN浇注时的最佳工艺参数与不启动M-EMS时相近。 8．M-EMS下，新四孔SEN的最佳结构与工艺参数为：S=S₂，β=β₂，α=α₄，h=h₃～h₄。与启动电磁搅拌、采用原四孔SEN浇注时的最优水平相比，t_均缩短了5.63～9.33Sec，液面鼓起高度减小了0.83～1.03mm，液面波动减小了1.17～1.2mm，S_碰、V_液相差不大。可以预言，采用新四孔SEN浇注，铸坯的等轴晶会有所提高。更多还原

【Abstract】 In modern continuous casting process, submerged entry nozzle (SEN) has been widely used, whose structural parameters and operating parameters affect the surface qualities and internal structure of the bloom by influencing the flow field and temperature distribution of molten steel in mold. So it is of great importance to study SEN.This paper based on studying a bloom mold of the No.1 Steel Plant of WISCO. According to the similarity theory, a water model in the ratio of 1 to 1 has been established. Applying tracing and photographing technology in the experiment, we studied the flow field in mold when different nozzle, such as the single-outlet-hole SEN, four-outlet-hole SEN, five-outlet-hole SEN and eight-outlet-hole SEN, is used, including starting M-EMS or not. As a result, the following results were found:l.When the immersion depth is hi~li2, the trumpet nozzle with single outlet hole is better than the straight nozzle with single outlet hole. When the former was used in casting, the impingement depth is shallower and the uniformity effect of temperature and component is better, at the same time, the heat center is upper which is propitious to the melt of mold powder, and then high quality bloom is acquired.2. The flow field in mold is not symmetrical because the four outlet holes’ axes of the primary nozzle with four holes is not vertical. Observing from inner arc side, the vortex appeared in left behind corner and right forward corner in liquid surface. The reasonable operating parameters of the primary SEN with four holes is that setting angle is 2~ 3,the immersion depth is h3 10mm.3. Compared with the primary nozzle with four holes , the improved funnel nozzle with five holes increased the impingement depth, which is not benefit for the inclusion floation.4. When we used the nozzle of eight holes in casting, even the immersion depth is h5, the surface fluctuation of liquid steel is still 2mm and there are some vortexes, which easily arosed entrapping slag.5. The optimum parameters for the new nozzle with four holes include that the nozzle’s outlet area ratio is S3, inclination of the SEN is 3 2, setting angle is 3 and the immersion depth is h2 10mm. Compared the new nozzle with four holes with the primary nozzle with four holes and the unproved nozzle with five holes, the former uniformity time decreased 1 second and 0.54 second, the impingement depth lowered 19.7mm and 31.4mm, the response time of surface reduced 0.92 second and 1.55 seconds, and the surface fluctuation of liquid steel is merely equal.6. When the flow velocity in the meniscus region is 0.30-0. 60m/s, the intensity of M-EMS is reasonable. In this experiment, the requisite power is 0.4-1. 2 W. In view of the mold being acontinuous reactor, the input power about 1.2W was selected.7. When the M-EMS was started, the optimum parameters for the primary nozzle with four holes are similar to the former parameters.8. When the M-EMS was started, The optimum parameters for the new nozzle with four holes includes that the nozzle’s outlet area ratio is S2, inclination of the SEN is 3 2, setting angle is 4 and the immersion depth is h3-h4. Compared this optimum level with that of the primary nozzle with four holes, the former uniformity time decreased 5.63 ~ 9.33 seconds, the protuberance height of the surface of liquid steel lowered 0.83 ~ 1.03mm, the surface fluctuation of liquid steel reduced 1.17 ~ 1.2mm, and the impact-point and the flow velocity in the meniscus region is almost equivalent. It could be concluded that the percentage of equiaxial crystal would increased when the new nozzle with four holes is used in casting.更多还原