STRADOMSKI Grzegorz Technical University of Częstochowa

Among the steel and cast steel resistant to corrosion most modern and dynamically developing group are ferritic-austenitic alloys, commonly known as duplex. Higher than austenitic steels, mechanical properties and good corrosion resistance in both overall and pitting make duplex steels irreplaceable material in the petrochemical industry, power, pulp and paper, food. Duplex steels and cast steels characterized by multiphase microstructure have a complex plasticity due the fact of deforming two different phase austenite and ferrite. The chemical composition of a steel containing about 0.02 % C , 26 % Cr, 6.5 % Ni, 3 % Mo , 1.4 % Mn , 0.2 % N guarantees that already, in the raw state, immediately after casting is obtained ferritic - austenitic structure. In this work was assumed that the starting material for the plasticity test will be the X2CrNiMo25-6-3 cast steel. From the material were taken samples with dimensions of 10x15x20 mm , which were deformed with different speeds 0.1 , 1 and 10 s- 1 in the temperature range from 850 to 1150 °C. To determine the plasticity was taken the compression test and the study was performed on the simulator Gleeble 3800 physical processes . The resulting flow curves were used to develop the nine parameters hansl - spittle equations forming the base material used in the computer simulation of the rolling process . In addition, in the paper was analyzed the changes in the microstructure of the material being deformed with the changing conditions. To evaluate the microstructure changes Nikon MA 200 optical microscope was used and samples were etched with the Mi21Fe reagent.