Vliv vysokoteplotní austenitizace a deformace na fázové transformace během ochlazování oceli P620Q

Abstract

The main aim of this bachelor thesis is to study the influence of high-temperature austenitization and deformation on phase transformations during cooling of P620Q steel. With using of the dilatometric tests for condition of high temperature heating on 1280 °C and deformation at temperature 900 °C the deformation continuos cooling transformation (DCCT) diagram was constructed. The metallographic analyses and hardness measurements HV30 were performed for verification of the dilatometric tests. From the reason of comparison of obtained results was the obtained DCCT diagram edited in the shape, which express the cooling curves and points of phase transformation directly after deformation at temperature 900 °C. The comparison of transformation diagrams leads to finding, that influence of the high-temperature austenitization and thus coarse grained austenite, caused decreasing of temperatures of ferritic and pearlitic transformation, shifting their noses to slower cooling rates, elimination of bainitic transformation (on the expanse of creation of acicular ferrite) and increasing of the temperature of martenzit start.