Pattern Evolvement of the Central Segregation and Looseness of the Continuous Casting Billet in Rolling Process

The segregation and shrinkage in the centre of the continuous casting billet can be evolved and deformed after rolling. The defect in the casting blank can be reduced and eliminated by using proper rolling compression ratio. The two kinds of 300 mm thick continuous casting billets of typical alloy steel and carbon steel rolled with different ratios. And the shape of the segregation and shrinkage in the continuous casting billet was analyze by using macro examination,hardness testing,metallographic examination and densitometry. The results showed that when the compression ratio was less than 4,plastic deformation can be found in the depth of 1/3 thickness from the surface of the casting blank under routine rolling process and the segregation and shrinkage in the centre can not be improved;when the compression ratio was larger than 5,the shrinkage in the centre(grade 1.5) can be rolled into conjunction,but the segregation in the centre can be reduced only.