Abstract: The mineral constitution, crystallizing ratio of phase and microstructure of mold flux films for casting ultralow carbon steel SPHC (0. 020% 〜0.055% C, 70mm slab, mold powder /% ： 33. 14SiO₂, 3. 86Al₂O₃, 3. 88MgO, 31. 52CaO, 8. 27K₂O + Na₂O, 7. 55F^-1, 3. 93C), peritectic steel SS400 (0. 18% ~0. 22% C, 70mm slab, mold powder /% : 29. 62SiO₂,4. 63Al₂O₃,2. 05MgO, 35, 86CaO, 10.43K2O + Na₂O, 7.55F^-1 3. 93C) and Ti microalloying steel Q345B (0. 15% ~0. 19%C, 0. 04% ~0. 05%Ti, 260 mm slab, mold powder /% : 31. 10Si02, 5. 21Al₂O₃, 5. 07MgO, 35,46CaO, 6. 22K₂O + Na₂0, 6. 96F^-1 , 6.96C) at Handan Steel have been systematically analyzed and compared by polarizing microscope. Results show that the alternative structure of “ crystallizing layer-amorphous layer” all occurs in three kinds of flux films from slab side to mold side. In SPHC steel flux film there is 90% ~95% amorphous phase, only minor cuspidine occurs in crystallizing phase, low crystallizing ratio is favourable to lubricate casting slab; in SS400 steel flux film the crystallizing ratio is about 55% - 60% , more cuspidine with partial melilite precipitates that is available to control slab heat transfer； the crystallizing ratio in Ti micro-alloy steel Q345B flux film is little higher than that in SS400 flux film, the precipitated melilite, cuspidine and wollastonite that meet the requirement of lubrication and heat transfer control, and are available to get nice slab quality.

摘要： 使用偏光显微镜,系统对比分析了邯郸钢厂超低碳钢SPHC(0.020%~0.055%C,70 mm板坯保护渣/%:33.14SiO₂,3.86Al₂O₃,3.88MgO,31.52CaO,8.27K₂O+Na₂O,7.55F^-1,3.93C)、包晶钢SS400(0.18%~0.22%C,70 mm板坯保护渣/%:29.62SiO₂,4.63Al₂O₃,2.05MgO,35.86CaO,10.43 K₂O+Na₂O,7.55F^-1,3.93C)和Ti微合金钢Q345B(0.15%~0.19C,0.04%~0.05%Ti,260 mm板坯保护渣/%:31.10SiO₂,5.21Al₂O₃,5.07MgO,35.46CaO,6.22K₂O+Na₂O,6.96F^-1,6.96C)对应的渣膜的矿相组成、结晶率和显微结构。结果表明,3种渣膜从铸坯至结晶器侧均呈现"结晶层-玻璃层"交替结构。SPHC钢渣膜有90%~95%的玻璃相,结晶相仅出现少量枪晶石,低结晶率有利于其润滑铸坯;SS400钢渣膜结晶率为55%~60%,析出较多的枪晶石和部分黄长石,有利于控制铸坯传热;Ti微合金钢Q345B渣膜结晶率略高于SS400钢,析出的黄长石、枪晶石和硅灰石能同时满足连铸对其润滑和控制传热的需求,可得到良好的铸坯质量。

关键词: SPHC, SS400,  , Ti微合金钢Q345B, 连铸保护渣, 渣膜, 矿相结构, 邯钢