Nizhniy Novgorod State Technical University (Nizhniy Novgorod, Russia):

Gushchin V. N., Dr. Eng., Prof., Chair of Metallurgical Technologies and Equipment, e-mail: guschinvn@rambler.ru
Ulyanov V. A., Dr. Eng., Prof., Chair of Metallurgical Technologies and Equipment

The paper examines the causes of appearance of axial porosity in continuously cast section billets and the methods for its decrease. Interaction between possibility of pores formation and heterogeneity of solidification front is established: it is defined by solidifi cation conditions and features of melt rate fields. Substantial effect of the dynamics of melt flow entering a continuous casting mould and its overheating on cast metal quality is confirmed. The developed technology provides more homogenous solidifi cation front and more intensive heat transfer to mold walls and from melt top, arising more early volumetric crystallization. Macrostructural investigations on 220×220 mm made of Steel 45 confi rm quality improvement of casting metals in axial porosity and central looseness for the case of applying the new construction of the steel pouring nozzle. This tendency is especially seen during melt overheating in a tundish below 30 °C. At the same time the calculated tendency of lowering of heterogeneity of solidification front along the perimeter of continuously cast billet by 1.5–1.9 times has been confirmed. It confirms indirectly presence of more uniform rate field when applying a steel pouring nozzle of improved modification.

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