Tertiary creep behaviour of 9Cr–1Mo ferritic steel

Physical Metallurgy of Modern Creep-Resistant Steel for Steam Power Plants: Microstructure and Phase Transformations

“…The steel (wt%: Fe-0.106C-8.96Cr-0.47Mo-0.051N-0.069Nb-0.20V-1.83W) contains tungsten which makes it more susceptible to Laves formation, which occurs over a greater range of temperatures than in the 10CrMoV steel. In the study in [47], Laves phase (Fe 2 Mo) and progressive coarsening of (CrFe) 23 C 6 carbides with respect to increasing test duration and temperature were observed. The formation and growth of Fe 2 Mo are reported to occur at Cr 2 N/matrix interface, caused by the depletion of Cr solutes in the vicinity of Cr 2 N precipitates [47].…”

“…In the study in [47], Laves phase (Fe 2 Mo) and progressive coarsening of (CrFe) 23 C 6 carbides with respect to increasing test duration and temperature were observed. The formation and growth of Fe 2 Mo are reported to occur at Cr 2 N/matrix interface, caused by the depletion of Cr solutes in the vicinity of Cr 2 N precipitates [47].…”

“…This phase is a complex nitride phase containing Cr, V, and niobium (Nb) (of the form Cr(Nb, V)N and it is found to form in close association with dissolving NbX particles [47,48]. As this phase grows, it is seen to gradually replace MX and M 2 X nitrogen-rich phases which improve the creep rupture strength [49].…”

Creep deformation and rupture behavior of Alloy 617

“…The validity in the MGR is weak because of C ≠ C MG . Similar to the MGR, the validity of the MMGR can also be observed as the slope of log (t r /ε f ) vs. logε m plot equals to unity [15][16][17][18][19]. When m′ = 1, the MMGR constant C′ becomes C MMG and the MMGR can be expressed as:…”

“…Creep damage can occur by various mechanisms such as loss of external cross-section, loss of internal cross-section (formation, growth and linkage of cavities at grain boundaries), degradation of microstructure (thermal-coarsening of particles and/or substructure-induced acceleration of creep), and oxidation. It is known that each damage micromechanism, when acting alone, results in a distinctive shape of the creep curve and a corresponding characteristic value of λ [16]. For λ = 1.5-2.5, the creep damage results from growth of cavities by coupled diffusion and power-law creep; for λ = 5 or more, it results from microstructural degradation such as coarsening of the precipitates and/or dislocation substructural softening [20].…”