Abstract
                 In this paper the defects influence on final quality of rolled flat products was researched. Cast slabs defects could be able to developped or limitted with rolling technology, which in the first place depend on type and size of the primary defects and used rolling parameters. Hot rolling is important by means of increasing portion of forming steels which are used as final product. Exact quality determination is essential for achieving of product characteristics, which are required by customers.
                 The aim of the work was follow and evaluate behavior of artificial defects in flat sample (”slab”) during its plastic deformation. Slab rolling was investigated with use of computer simulation, where the parameters of process were chosen. Experiment was made in DEFORM 3D software, for simulating the rolling process. Artificial defects of type V and U scores, were applied to a “slab“, which had different size, design and location. Hot-rolling process was simulated for heating temperatures 1250°C and deformation temperatures 1200°C, 900°C. Proportionate amount of deformation 10% a 50%  was applied on specific temperatures. The second part of experiment introduces the cold-rolling simulation process (temperature 23°C), which was applicated in relative amount of deformation 10%. Results of this simulation showed, that  influence defects didn´t  expanded  in 10 % deformation, which was apply for the simulation deformation temperatures (ambient temperature). Development of primary defects  were observated in raising relative amount of deformation on the level of  50%, where overlaps and scratches were observated.