Micro-inclusions in slab include part of La, Ce, K and Na.The reason is that the deoxidization products in molten steel react with the ladle slag, tundish flux and mould flux.

• 板坯中的显微夹杂物含有镧、铈、钾、钠中的几种，说明钢液脱氧产物与钢包渣、中间包覆盖剂、结晶器保护渣均产生了反应。