The Effect of Creep and Long Annealing Conditions on the Formation of the Z-Phase Particles

The influence of the temperature, applied stress, degree of creep deformation, and aging time on the formation of Z-phase (CrVN) particles in 9% Cr 10Kh9K3V2MFBR martensitic steel at temperatures of 650 and 675°С upon long aging is studied in this work. The particles with a chemical composition determined by energy dispersive spectrometry as 50% (Cr + Fe) and 50% (V + Nb) are detected and identified as particles of the Z‑phase. An increase in the creep test time at both temperatures led to the growth of Z-phase particles. An increase in the temperature provokes earlier nucleation of small Z-phase particles with a change in the mechanism of their nucleation. An enlargement of particles is observed upon localization of plastic deformation. Long-term annealing at temperatures of 650 and 675°C does not lead to the formation of Z-phase particles. Plastic deformation has a crucial effect on the formation of Z-phase particles in steels containing 9% Cr. The temperature, time, applied stress, and strain localization are aggravating factors that cause the growth of this phase.