降低过热度对方坯凝固组织的影响

Effect of Decreasing Superheat Temperature on Solidification Structure of Billet

结晶器内钢液过热度的降低可以促进柱状晶向等轴晶的转变和提高等轴晶率,从而有利于铸坯组织的均质化。基于上述原理,设计和制造了可用于降低钢液过热度的冷却水口,并在方坯连铸机上进行了工业试验,分析了低过热度技术对方坯凝固组织的影响。结果表明：采用冷却水口以后,结晶器内钢液过热度的下降幅度可达14℃,铸坯的等轴晶率提高了8%-24%,中心偏析和缩孔严重程度有所降低。

The transformation from columnar grain to equiaxed grain would be promoted by decreasing superheat temperature of liquid steel in the mould,which was beneficial for homogenization of billet structure.Based on above-mentioned theory,a cooling nozzle for decreasing superheat temperature was designed and fabricated.Commercial trials were carried out on a billet caster using the cooling nozzle.The effect of the low superheat degree technology on solidification structure of billet was analyzed.The results show that the degree of superheat is reduced by 14 ℃ with the cooling nozzle.The equiaxed grain ratio of billet produced by the cooling nozzle is increased by more than 8%-24% and the severity of center segregation and cavitation are reduced.