Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (SE) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20 000 h and 50 000 h at 650℃ and 600℃, respectively.