Nb-V-Ti微合金化低合金钢SG610E 250 mm×2000 mm连铸尾坯封顶工艺试验与实践

针对低合金钢SG610E 250 mm ×2 000 mm连铸尾坯封顶工艺进行了试验研究,结果表明,传统的打水封顶工艺,在距离铸坯尾部2 000 mm范围内存在严重的中心缩孔,而低拉速无水封顶可以将缩孔尾坯长度减小到了 900 mm。但是由于低拉速无水封顶工艺,拉速≤0.2 m/min持续时间长,导致连铸坯表面温度降低,进入第三脆性区,Nb-V-Ti微合金化低合金钢连铸尾坯表面出现了表面横裂纹。为此,开发了一种宽厚板连铸机拉速0.4 m/min不停机无水封顶方法,不仅获得了良好的连铸尾坯内部质量,同时解决了该钢连铸尾坯表面横裂纹的问题。

Test and Practice on Capping Process of 250 mm x 2 000 mmCasting Tail Slab of Nb-V-Ti Microalloying Low Alloy Steel SG610E

The capping technology of low alloy steel SG610E 250 mm x2 000 mm continuous casting tail slab is studied. The results show that with traditional water-cooling capping process, there are severe shrinkage cavities at distance 2 000 mm from the slab end；while with the low-speed casting anhydrous capping,the distance of slab shrinkage cavities decreases to 900 mm,but the slab surface temperature drops into the third brittle zone due to the long duration of ≤0. 2 m/ min casting speed, which lead to transverse cracks on Nb-V-Ti microalloying low alloy steel casting tail slab. Therefore, a non-stopped-pouring speed casting 0.4 m/min anhydrous capping technology for wide and thick slab is developed which improves the internal quality and reduces the surface crack incidence of the steel tail slab.