Prévention of segregation in continuous casting of Steel : new process and industrial development at Unimétal Neuves-Maisons works^*

Prévention des ségrégations en coulée continue des aciers : nouveau procédé et développement industriel à Unimétal Neuves-Maisons

Abstract

For billets and blooms, centerline segregation and V-segregates résuit from the cracking of the mushy zone under thermomechanical deformations inducing tension in the product core. Segregation level can be reduced by a control of the differential deformations between the solidified shell and the mushy zone at the vicinity of the liquid pool end. This goal can be reached by a precise control of the cooling of the product shell. Experiments on high ingots and industrial results on a billets continuous caster confirm the theoretical approach.

This new process, called Unitherm, makes it possible to reduce certerline segregation in long products, better than a combined electromagnetic stirring (in mould and final EMS) for high carbon steel grades. This paper presents the results obtained at the semi-industrial and industrial scales.