The article discusses problems related to the infl uence of rolling processes on the progress of closing external discontinuities in continuous ingots during rolling. Numerical and experimental studies of the rolling process of fl at bars for feedstock with material discontinuities simulating surface cracks were conducted. The rolling process was conducted in three designed shaping grooves. The experimental studies were conducted in a D150 laboratory rolling mill. The numerical simulations were carried out using the Forge 2008® software programme. In the research, the S355J2G3 structural steel was used and its chemical composition was in accordance with requirements of the norm EN 10027-1. The study analysed temperature distribution as well as intensity of deformation and stress in a cross-section of a strand located in the consecutive shaping grooves. Changes in the shape of the surface defects and their surface areas after rolling were examined. After the rolling process, macroscopic pictures of the defects were taken. The sum of the surface areas of the discontinuities in a sample before rolling amounted to about 60.0 mm2. After the third rolling stand, the sum of the surface areas of the discontinuities in the same sample amounts to 4.7 mm2, and about 3.6 mm2 according to the numerical computation. The defects were closed in 92.15% in case of samples rolled in an experimental rolling mill, and in 94.05% in the numerical studies. It was stated that the speed of closing of material discontinuities in feedstock is strongly infl uenced by the shape of the rolling groove.
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