This paper deals with the analysis of microstructure and mechanical properties of 9 Cr steel after austenitizing at temperatures of 1150 °C, 1180 °C and 1210 °C/2 hrs and after tempering at temperature of 790 °C/1 hr. Microstructure after austenitizing and quenching was formed of lath martensite and uniformly distributed ferritic area. At temperature of austenitizing of 1150 °C microstructures were relatively homogeneous. At higher austenitizing temperature of 1180 °C and 1210 °C microstructure was significantly heterogeneous. With increasing austenitizing temperature there was a significant increase of the original austenite grain boundaries. After tempering was microstructure formed by tempered martensite, with lath morphology. The results of mechanical properties (Rp0,2, Rm, HBW, KV2) are in good agreement with requirements for grade P91 and P92 according to the relevant norm of STN EN 10216-2+A2. The minimum values of ductility A5 accordance with that norms were not achieved, where values were lower about 1.1 – 2.1 % compared with the prescribed value of ductility for grade P92 (min.19 %).Keywords: Creep resistance steel, kinetics of grain growth in austenite, austenitizing temperature, tempering temperature, low carbon 9Cr steel
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