In Železiarne Podbrezová, cold drawing process is the final process in production of precision seamless steel tubes. This particular technology utilizes multiple drawing sequences and intermediate annealing. From the physical point of view, it is nothing just the optimal use of plastic deformation during cold forming that grants the final tube dimensions. The drawing process itself is significantly affected by physical and metallurgical properties of the tube, the tool geometry, the lubrication, and the sequence of operations. This paper deals with the relationship between the tool geometry and the drawing force. The FEM-based numerical model of the process was prepared in DEFORM 3D in order to optimize the geometry of the die; eight die geometries were investigated in total. The numerical simulation itself considered a hot rolled hollow at Ø32 mm × 4 mm, cold drawn into Ø25 mm × 4 mm using die drawing (sinking) sequences only. Calculated drawing force showed that the change of the run-in angle of the die led to a decrease of the drawing force.

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Measurement by computed tomography is very useful in evaluation of dimensions and internal structure. There are still some problems which need to be solved. Scanning accuracy depends, among other things, on the part´s material. Metal parts have high density and their scanning leads many times to failure. This paper deals with evaluation of accuracy of seamless steel tube scanning by industrial computed tomography. This method of scanning can lead to substitution of destructive method for measurement, but it is necessary to have knowledge if the scan has required accuracy. The tube with different diameters in length is scanned by X-Ray beam and it is evaluated inner and outer diameter, concentricity and wall thickness in 8 sections. The accuracy of scan is compared with reference values achieved by coordinate measuring machine in the same sections.

Steel 7CrMoVTiB10-10 is a Cr-Mo medium alloy steel with addition of vanadium and titanium as microalloying elements and with further addition of boron. The resulting microstructure after the heat treatment takes the form of a tempered bainite. In hot rolling of seamless tubes using this particular steel grade, it is very important to find the optimum heat treatment parameters in order to obtain the final mechanical properties according to STN EN 10216-2+A2. In this paper, various optimization concepts regarding temperature and time of tempering are being presented. Results obtained were utilized in production of seamless steel tubes in Železiarne Podbrezová.