长水口吹氩生成微小气泡工业实验研究

在连铸生产中采用大流量长水口吹氩，并采用“冷钢片沾钢法”沾取中间包钢液试样，成功沾取了中间包钢液中微小氩气泡。冷钢片沾样表面气泡为中间包上部钢/渣界面和炉渣中氩气泡，尺寸主要位于1.0~3.0 mm，但该尺寸不能反映中间包钢液内部长水口吹氩生成气泡，冷钢片沾样内部气泡为钢液内部长水口吹氩生成的气泡。结合扫描电镜和共聚焦显微镜对沾取试样内部气泡形貌、尺寸和数量进行了分析，结果表明大部分气泡为独立圆形气泡，偶见少量粘连和聚合气泡；钢液内部氩气泡尺寸主要位于100~1000 μm，平均尺寸为500 μm左右；气泡在长水口出口及其下方较为弥散，气泡数量可达15.2 cm?2。采用扫描电镜结合能谱分析，发现部分气泡内粘附有夹杂物，有些气泡粘附多个夹杂物；气泡粘附Al₂O₃夹杂物的几率高于粘附CaO(?MgO)?Al₂O₃?SiO₂复合夹杂物的几率。 

Industrial experimental study on the formation of microbubbles by argon injection into ladle shroud

Using bubbles to remove inclusions in steel is rapidly becoming a popular method for refining. Fine bubbles are thought to be more effective on inclusion removal than big bubbles. The fine bubbles can be formed in molten steel using the argon injection into ladle shroud technology. There are two stages during the formation of fine bubbles in ladle shroud: bubble detachment from wall orifice and detached bubbles splitting into smaller ones in turbulent steel. Many reports have been published on the water model of the argon injection into ladle shroud technology, but industrial experimental research is in its early stage. In this study, high argon flow was injected into a ladle shroud and adopted in continuous casting production to produce fine argon bubbles in a tundish. The bubbles were captured by dipping a cold steel sheet into molten steel. The captured bubbles at the surface of a hot-dipped steel sheet, with a size of 1.0–3.0 mm, characterized the argon bubbles at steel/slag interface and slag phase in the upper part of a tundish rather than those inside molten steel in tundish. The bubbles inside molten steel in tundish were characterized by the captured bubbles in the interior of a hot-dipped steel sheet, and their morphology, size, and number were analyzed using scanning electron microscopy and confocal microscopy. The bubbles inside molten steel in tundish have a spherical shape and occasionally adhere to each other. These bubbles rang in size from 100 to 1000 μm, with an average of 500 μm. They are dispersed at the exit of a ladle shroud in its lower position, with a density of 15.2 cm–2. Moreover, it was observed that a bubble could adhere to inclusion, even multiple inclusions for part of bubbles. Bubbles adhered more strongly to Al₂O₃ inclusions than that to CaO(?MgO)?Al₂O₃?SiO₂ complex inclusions.