Industrial experimental study on the formation of microbubbles by argon injection into ladle shroud
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摘要: 在連鑄生產中采用大流量長水口吹氬，并采用“冷鋼片沾鋼法”沾取中間包鋼液試樣，成功沾取了中間包鋼液中微小氬氣泡。冷鋼片沾樣表面氣泡為中間包上部鋼/渣界面和爐渣中氬氣泡，尺寸主要位于1.0~3.0 mm，但該尺寸不能反映中間包鋼液內部長水口吹氬生成氣泡，冷鋼片沾樣內部氣泡為鋼液內部長水口吹氬生成的氣泡。結合掃描電鏡和共聚焦顯微鏡對沾取試樣內部氣泡形貌、尺寸和數量進行了分析，結果表明大部分氣泡為獨立圓形氣泡，偶見少量粘連和聚合氣泡；鋼液內部氬氣泡尺寸主要位于100~1000 μm，平均尺寸為500 μm左右；氣泡在長水口出口及其下方較為彌散，氣泡數量可達15.2 cm?2。采用掃描電鏡結合能譜分析，發現部分氣泡內粘附有夾雜物，有些氣泡粘附多個夾雜物；氣泡粘附Al2O3夾雜物的幾率高于粘附CaO(?MgO)?Al2O3?SiO2復合夾雜物的幾率。Abstract: 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.
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Key words:
- bubble /
- inclusion /
- tundish /
- ladle shroud /
- argon injection
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圖 1 連鑄長水口保護澆注與吹氬保護裝置示意圖
Figure 1. Schematic diagram of protective casting using a ladle shroud and argon injection device
圖 2 長水口吹氬氬氣流股流動示意圖
Figure 2. Schematic diagram showing argon stream flow in ladle shroud
圖 3 冷鋼片沾鋼法示意圖
Figure 3. Schematic diagram of dip sampling method using a cold steel sheet
圖 4 冷鋼片沾樣表面氣泡形貌. (a) 1-豎片; (b) 2-豎片（爆裂氣泡坑）; (c) 2-橫片表（渣皮爆落）
Figure 4. Shape of bubbles on the surface of a cold steel sheet: (a) 1-vertical steel sheet; (b) 2-vertical steel sheet (bubble collapse cavity); (c) 2-horizontal steel sheet (slag layer falls off)
圖 5 冷鋼片沾取試樣表面氣泡尺寸分布圖
Figure 5. Bubble size distribution on the surface of a cold steel sheet
圖 6 冷鋼片沾樣內部氣泡形貌. (a) 第1爐次; (b) 第2爐次
Figure 6. Shape of bubbles in a cold steel sheet: (a) the first test and (b) the second test
圖 8 冷鋼片沾取試樣中單個球形氣泡形貌及直徑尺寸
Figure 8. Shape and size of single spherical bubble in a cold steel sheet
圖 9 冷鋼片沾取試樣中粘連與聚合氣泡形貌及尺寸
Figure 9. Shape and size of adhesive and polymeric bubbles in a cold steel sheet
圖 10 冷鋼片沾樣內部氣泡尺寸分布掃描電鏡分析結果
Figure 10. Bubble size distribution in a cold steel sheet using SEM
圖 11 沾鋼片表面氣泡形成示意圖
Figure 11. Diagram of bubble formation on the surface of a steel sheet
圖 12 渣層覆蓋的氣泡表面受力示意圖
Figure 12. Diagram of forces on the bubble surface covered with a slag layer
圖 14 氣泡粘附夾雜物和夾雜物成分能譜分析結果. (a)粘附Al2O3夾雜; (b)粘附CaO?Al2O3?SiO2復合夾雜
Figure 14. Bubbles adhere to inclusions and inclusion composition: (a) Al2O3; (b) CaO?Al2O3?SiO2
久色视频表 1 冷鋼片沾取試樣表面氣泡數量及平均尺寸
Table 1. Number and average size of bubbles on the surface of a cold steel sheet
Number of
steel sheet0–1.0 mm 1.0–3.0 mm 3.0–5.0 mm 5.0–10.0 mm Total Average size/mm 1-vertical
steel sheet0 37 19 4 60 3.12 2-vertical
steel sheet0 48 10 13 71 3.02 2-horizontal
steel sheet0 28 5 0 33 2.13 
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