The structure of columnar crystals is observed for billets cast without M-EMS,and equiaxed structure for billets cast with M-EMS,in which SDAS decreases obviously with increase of stirring current.

• 无M-EMS的铸坯接近中心的区域,仍然是枝晶臂发达的柱状晶组织;采用结晶器电磁搅拌,促使铸坯中心区域形成粒状等轴晶组织;随搅拌电流增大,二次枝晶间距明显减小。