连铸板坯中碳钢开浇用发热保护渣

Exothermic Start Mould Powder for Medium Carbon Slab

连铸板坯开浇时的浇铸状况恶劣,开浇炉的铸坯表面缺陷发生率较高。使铸坯在结晶器内缓冷是防止铸坯纵裂的有效措施。针对通常使用的低碱度、低结晶温度的发热型开浇渣不能使铸坯在开浇阶段得到缓冷的缺点,开发了连铸板坯中碳钢开浇用发热保护渣,除进一步改善发热性能外,高碱度、高结晶率的开浇渣所形成的渣膜增大了结晶器与铸坯间的热阻,改善了铸坯在结晶器内的缓冷条件,开浇炉的第1、2块板坯的纵裂发生率明显下降。

The rate of surface defect formation of slabs in the first heat is the highest, especially for surface longitudinal cracking, because the casting conditions at start are very unstable. Slow cooling of solidified shell in the mould is the effective measure to prevent slab from longitudinal cracking. Comparing with common start exothermal mould powder, which is not effective for slow cooling of slab because of low basicity and low crystallization temperature, a special powder developed for medium carbon steel has enhanced exothermal property, which can improve the cooling condition of slab in the mould because the formed slag film of high basicity and high crystallization rate increases the heat resistance between mould and shell. The rate of longitudinal crack formation in the first and second slabs has been decreased obviously with the use of special powder.