连铸结晶器内钢/渣界面波动及卷渣行为的实验研究

连铸结晶器钢/渣界面时常发生卷渣现象,严重影响连铸坯质量.本文通过水模型实验研究了吹氩量、拉速、水口浸入深度对钢/渣界面波动及卷渣现象的影响.利用波高仪采集液面的波动数据,采用高速摄像机捕捉钢/渣界面卷渣时的瞬时图像,重现了剪切卷渣、漩涡卷渣、大气泡卷渣及抽吸卷渣现象.结果表明:随着吹氩量的增大,结晶器液面波动加剧,适当的吹氩量有利于抑制卷渣,本实验中0.8 L/min吹氩量下的卷渣频率最低;随着水口浸入深度的增加,液面波动程度和卷渣频率均呈降低趋势;随着拉速增大,水口附近的波动先减小后增大,窄边附近的波动逐渐增强,卷渣频率逐渐增大.

Experimental study on the mechanism of slag entrainment at the slag/metal interface in continuous casting

Slag entrainment during continuous casting process is a major reason for deteriorated billet quality.In this paper,a water model experiment was carried out to study the effects of operating parameters such as gas flow rate,casting speed and the immersion depth of nozzle on the fluctuation of slag/metal interface and slag entrainment.In this experiment,the time-history of liquid surface height was recorded by wave height instrument and the instantaneous picture of entrainment was captured by high speed cameras.Several classical entrainment mechanisms were identified here,such as entrainment by shear-layer instability,entrainment by von Kármán vortex formation,entrainment by bubble penetration through slag layer and entrainment by slag crawling.The results showed that the fluctuation of liquid surface grows stronger with the increase of gas flow rate.A proper gas flow rate is beneficial to inhibit entrainment.In this experiment,the entrainment frequency was minimized at the gas flow rate of 0.8L/min.With increasing nozzle immersion depth,both the fluctuation of liquid surface and the entrainment frequency decline.With the increase of casting speed,the fluctuation near the nozzle first decreases and then increases,while that near the narrow edges keeps increasing.The entrainment frequency goes up as the casting speed increases.