CSP薄板坯的铸态组织特征研究

STUDY ON CHARACTERISTICS OF ASCAST STRUCTURE OF CSP SLAB

对CSP的铸坯组织、化学成分偏析、枝晶间距、气体含量、夹杂物以及轧制过程中的组织变化进行了研究,结果表明:CSP薄板坯的低倍组织在结构上和传统板坯没有本质区别,但薄板坯组织较为细密,柱状晶比较发达,一次枝晶与二次枝晶间距小,化学成分均匀,铸坯全氧含量为28×10-6,氮含量为47×10-6;第一道次轧制后中心部的疏松和偏析明显减轻,树枝晶沿轧制方向弯曲,但没有被打碎;CSP铸坯中大颗粒夹杂物较少,主要是外来的;内生夹杂物主要以含氧化铝和铝酸盐及氧化钙的为多,尺寸基本都在10μm以内,大部分在2～5μm。

The ascast microstructure, chemical composition segregation, dendrite arm spacing, gas content, inclusion and microstructure evolution during CSP rolling process were investigated. The results show that there is no much difference between CSP slab and conventionally cast slab for macrostructure. However, the macrostructure of CSP slab is relatively finer. The oxygen content of CSP slab is 28×10-6 and the nitrogen content of the CSP slab is 47×10-6.After the first pass, the porosity in the center of the CSP slab and the segregation are obviously improved. The dendrite is bent along the rolling direction, instead of being broken to pieces. The big inclusion is minor in the CSP slab. The size of most inclusion ranges from 2 to 5 μm.