Formation of Nano M_2X Particles by a Tempering in High Cr Ferritic/Martensitic Steel

摘要

The precipitation of nano Cr_2N particles in high Cr FM steels has been studied. The nitrogen content of the FM steels was changed to form stable Cr_2N particles. Tempering temperature was also changed from 500 ℃ to 800 ℃ to study the precipitation behavior of the Cr_2N particles with the tempering temperature. The Cr_2N particles remained as a stable phase at a higher tempering temperature by increasing the nitrogen content. The shape of these particle was a fine needle type which was very similar to V(C,N) particles. The size of some Cr_2N particles was increased as the nitrogen content increased. But these precipitates were not dissolved or largely coarsened during a creep deformation at 600℃. So it seems that they may act as an effective obstacle against a dislocation glide during a creep deformation, thus contribute to an increase of the creep rupture strength in high Cr FM steels.