Abstract:  In order to improve the quality of vertical continuous casting 40Mn2 square bloom ， a four-quarter tangential swirl nozzle was proposed， using a Particle image velocimetry technique， the molten steel flow and slag interface behavior at different casting speeds and nozzle immersion depths were studied in a steel plant's bloom mold with 410 mm × 560 mm vertical continuous casting section. The results show that the fluidity of the mold powder at the interface of steel slag is poor when the depth of the nozzle is 90 mm and the casting speed is 0.25 m/min， and the slag entrapment occurs when the casting speed is 0.35 m/min and 0.45 m/min，When the immersion depth of the nozzle is 100 mm， the fluidity of the mold powder at the interface of steel slag is poor while the casting speed is 0.25 m/min， and at 0.35 m/min casting speed ， the inclusion will float upwards. The interface of steel slag is active and there is no slag entrapment， and slag entrapment will occur at 0.45 m/min casting speed . When the immersion depth of the nozzle is 110 mm， the fluidity of the mold powder at the interface of steel slag is poor while the casting speed is 0.25 m/min. When the casting speed is 0.45 m/min， the slag entrapment will occur. When the casting speed is 0.35 m/min， no slag entrapment will occur， compared with the same casting speed and 100 mm immersion depth of nozzle， it is unfavorable to the floating of inclusions. Combined with the actual production practice， the optimum operating parameters of the vertical continuous casting bloom mold are the depth of nozzle immersion 100 mm and casting speed 0.35 m/min.

Key words: Swirl Nozzle, Vertical Continuous Casting, Slag Interface, Bloom Mould, Flow Field

摘要： 为了提升立式连铸40Mn2大方坯铸坯质量，提出了一种四分切向旋流水口，利用粒子图像测速技术，以某钢厂立式连铸断面尺寸410 mm×560 mm的大方坯结晶器为研究对象，研究不同拉速和水口浸入深度工况条件下的钢液流动和钢渣界面行为。结果表明，水口浸入深度为90 mm，拉速为0.25 m/min时钢渣界面保护渣流动性较差，拉速为0.35、0.45 m/min时会发生卷渣；水口浸入深度为100 mm，拉速为0.25 m/min时钢渣界面保护渣流动性较差，拉速为0.35 m/min时有利于夹杂物上浮，钢渣界面活跃且无卷渣现象发生，拉速0.45 m/min时会发生卷渣；水口的浸入深度为110 mm，拉速为0.25 m/min时钢渣界面保护渣流动性较差，拉速0.45 m/min时会发生卷渣，拉速为0.35 m/min时无卷渣现象发生，与同拉速、水口浸入深度为100 mm的工艺条件相比不利于夹杂物的上浮。结合生产实际可得，水口浸入深度100 mm，拉速0.35 m/min是立式连铸大方坯结晶器较适宜的操作参数。

关键词: 旋流水口, 立式连铸, 钢渣界面, 大方坯结晶器, 流场