RUSZ Stanislav VŠB -Technická univerzita

Spoluautoři SCHINDLER Ivo, SOJKA Jaroslav, KAWULOK Rostislav, KAWULOK Petr, TUROŇOVÁ Petra, TUROŇ Rostislav

Due to heterogeneity of structure and to casting defects contained in surface layers of continuously cast blanks with large cross sections the study of their deformation behaviour, and namely of their hot formability is a highly demanding task. Exact plastometric methods in the case of taking of the samples from surface areas do not provide acceptable results, since due to their small sizes they cannot express sufficiently the present structure heterogeneity. Surface layers of material, in which it is possible to expect the biggest occurrence of defects that expand at the subsequent forming till they achieve character of critical cracks, are then removed from the samples by machining. For these reasons the wedge rolling test, performed in partly non-machined samples, proved to be successful for investigation of these continuously cast blanks. One of the freely spreading side surfaces of the sample corresponds to the raw surface of the casting and it is then possible to use it then from efficient investigation of effects of reduced technological formability. This approach was used for investigation of deformation behaviour of low alloyed steels of the type C-Mn-Cr, microalloyed by vanadium or niobium. The heating temperature (1150 to 1340 °C) and rolling temperature (950 to 1150 °C) were the changed parameters. The obtained results were supported by metallographic analyses in non-etched and etched states, by TEM and SEM analyses of present particles (inclusions and precipitates).