This work deals with the influence of heat treatment on the microstructure and mechanical properties of chromium martensitic stainless steel X20Cr13. Three different austenitization temperatures and three different cooling rates accomplished by quenching in water, oil and air were used. Each sample of steel has been additionally tempered at constant temperate for two different times. Microstructure of heat treated steel was characterized by using light microscopy and prior austenite grans size was determined according to ASTM E112. Dilatometry was used to determine the Ac1, Ac3, Mf, Ms temperatures. Mechanical properties were determined by using tensile testing, impact toughness testing and hardness testing. Scanning electron microscopy was used for the characterization of fracture morphology. Fracture appearance transition temperature (FATT) was also determined for this steel heat treated by different procedures. On the basis of these properties the optimal heat treatment procedure for this steel was selected. Such a heat treatment involves austenitization temperature of 1000 °C followed by quenching in air and tempering at XXX °C for 5 hours.
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