电磁制动对镀锡板高拉速结晶器内流场的影响

Effect of electromagnetic braking on flow field in tinplate under high casting speed

为了实现镀锡板高拉速生产,采用数学模型和工业试验研究了在FC(电磁制动)结晶器条件下水口角度、水口插入深度、拉速及磁场强度对结晶器流场特征的影响。研究结果表明,随着水口角度、插入深度和拉速的增加,下磁场作用区域靠近窄面的钢液受到的电磁力明显增大,水口下方的磁场可有效地减小水口出口射流对窄面的冲刷;在工业试验中发现,施加磁场后水口两侧钢液面流速对称性得到改善,钢液面轮廓较平稳,当BU(上磁场强度)为0.5BL(下磁场强度)时液位波动最小;夹杂物明显降低,边部大于10μm夹杂物数量密度从0.134降低到0.079个/mm^2,1/4处夹杂物数量密度从0.129降低到0.074个/mm^2,宽度中心处数量密度从0.100降低到0.073个/mm^2;凝固钩的长度和深度都有明显的降低作用,平均深度从2.3降低到1.7mm,平均长度从2.3降低到2.0mm,适合的电磁制动参数可以抑制凝固钩的生长。通过优化FC结晶器参数,氧化铝类缺陷降低约77.8%,保护渣类缺陷降低约82.6%,并且在工业上实现了拉速为2.0m/min的常态化生产。

In order to realize high casting speed production in tinplate,the effects of nozzle angle,nozzle immersion depth,casting speed and magnetic field intensity on characteristics of flow field under the condition FC mold were studied by mathematical model and industrial test.The results show that the electromagnetic force near the narrow surface in the lower magnetic field increases obviously with the increase of nozzle angle,immersion depth and casting speed,and the magnetic field below the nozzle can effectively reduce the erosion of nozzle outlet jet on the narrow surface.The symmetry of flow velocity on both sides of the nozzle was improved after applying magnetic field,and the level profile in mould was relatively stable.When BUwas equal to 0.5 BL,the fluctuation of mould level was the smallest.Inclusions decreased significantly by applying magnetic field,the number density of inclusions at the edge>10μm decreased from 0.134 to 0.079/mm^2,the number density at one quarter decreased from 0.129 to 0.074/mm^2,and the number density at the center of width decreased from 0.100 to 0.073/mm^2.The average depth of hook decreases from 2.3 to 1.7 mm and the average length of hook decreases from 2.3 to 2.0 mm.The growth of the hook can be inhibited by appropriate electromagnetic parameters.By optimizing the parameters of FC mold,the defects of alumina and mold powder in tinplate are reduced by 77.8%and 82.6%respectively,and the casting speed of2.0 m/min is realized in industry.