Creep rupture properties of nitrogen added 10Cr ferritic/martensitic steels

The effect of nitrogen on creep rupture strength and microstructure evolution in 10Cr–N steels has been studied. Creep testing was carried out at 600 and 650 °C under constant load conditions. The prior austenite grain size and martensite lath width were decreased by addition of nitrogen. The Cr2X precipitates were stabilized at 750 °C as the nitrogen content increased. The 0.08 wt% N steel had a minimum martensite lath width and finer Cr2X precipitates in the as-tempered state. Creep rupture strength increased with increasing nitrogen content. The optimum nitrogen content for creep rupture strength was 0.08 wt% in 10Cr ferritic/martensitic steels, and Cr2X precipitates were not dissolved after creep deformation. These fine and stable Cr2X precipitates may contribute to the increase of creep rupture strength.