Effect of W–Mo balance on long-term creep life of 9Cr steel

Abe, Fujio; Ohba, Toshio; Miyazaki, Hideko; Toda, Yoshiaki; Tabuchi, Masaaki

doi:10.1080/09603409.2018.1555202

Cited by 13 publications

(4 citation statements)

References 13 publications

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“…The chains of Laves phase induce a high Zener drag force, preventing migration of the lath boundaries, and provide the stability of the tempered martensite lath structure under creep conditions [6,17,32], that compensates for the depletion of W and Mo atoms from the solid solution. On the other hand, the fast growth of Laves phase promotes an increase in the creep rate and premature failure [2,3,16,18,22,25,26,37,[39][40][41]. Coarse Laves phase particles located at the boundaries of prior austenite grains (PAGs) act as cavity nucleation sites initiating premature damage that decreases the strain to rupture [25].…”

Section: Introductionmentioning

confidence: 99%

Effect of Alloying on the Nucleation and Growth of Laves Phase in the 9–10%Cr-3%Co Martensitic Steels during Creep

Fedoseeva

Nikitin

Tkachev

et al. 2020

Metals

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Five Co-modified P92-type steels with different contents of Cr, W, Mo, B, N, and Re have been examined to evaluate the effect of the chemical composition on the evolution of Laves phase during creep at 650 °C. The creep tests have been carried out at 650 °C under various applied initial stresses ranging from 80 to 200 MPa until rupture. An increase in the B and Cr contents leads to a decrease in the size and volume fraction of M23C6 carbides precipitated during tempering and an increase in their number particle density along the boundaries. In turns, this affects the amount of the nucleation sites for Laves phase during creep. The (W+Mo) content determines the diffusion growth and coarsening of Laves phase during creep. Susceptibility of Laves phase to coarsening with a high rate is caused by the large difference in Gibbs energy between fine and large particles located at the low-angle and high-angle boundaries, respectively, and can cause the creep strength breakdown. The addition of Re to the 10%Cr steel with low N and high B contents provides the slowest coarsening of Laves phase among the steels studied.

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Section: Introductionmentioning

confidence: 99%

Effect of Alloying on the Nucleation and Growth of Laves Phase in the 9–10%Cr-3%Co Martensitic Steels during Creep

Fedoseeva

Nikitin

Tkachev

et al. 2020

Metals

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“…This may be related to the high ductility of the alloy. Abe et al [ 12 ] showed that for a 9Cr steel with high N concentration resulting in the formation of a large amount of BN particles, the RA was degraded compared to the equivalent steel with low N and no BN precipitates observed. In the present investigation, alloy HBN consistently showed greater elongations to failure and reductions of area for all creep conditions investigated.…”

Section: Discussionmentioning

confidence: 99%

“…[10,11] The formation of large BN can also promote the growth of cavities during creep and affect creep ductility. [12] Additionally, very high B additions have been shown to adversely impact the weldability of these steels. [13,14] On the other hand, the N content is particularly important as too little minimizes the formation of essential MX particles, while too much promotes the formation of BN and/or Z-phase.…”

Section: Introductionmentioning

confidence: 99%

Variations in Creep Performance of P92 Steel Within Its Composition Range: Influence of N Solubility

Detrois

Antonov

Hawk

et al. 2023

steel research int.

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Underspecified composition ranges often lead to alloys with unpredictable mechanical performance. To better understand the changes in microstructure and mechanical performance associated with variations of key elements, three versions of P92 are formulated within, or close to, the specified allowable for N, B, and C ranges. Chromium and Si are also varied to influence N solubility. Different service conditions (i.e., temperature and stress) are explored. It is observed that >80% decrease in creep life occurs at 625 °C and 155 MPa for the highest B and N containing alloy. Multiscale characterization reveals key changes due to the trace element variation. The high B and N containing alloy forms deleterious BN precipitates with morphology that promotes crack nucleation and damage accumulation, but this alloy additionally forms higher fractions of beneficial MX precipitates. The alloy with the lowest B and N concentrations but greater C content shows the best creep performance—a consequence of the refined M23C6 carbide precipitate population and the absence of large‐scale inclusions or BN precipitates. Calculations of creep activation energy reveal that the high B and N containing alloy is more prone to damage accumulation which causes an early onset of accelerating creep and greater minimum creep rate.

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“…Strain-induced coarsening of M 23 C 6 carbides and replacement of the nanoscale M(C,N) carbonitrides by the coarse Z-phase (Cr,V)N particles are responsible for instability of the TMLS under creep conditions [1,3,[9][10][11][12][13][14][16][17][18][19][20][21]. Precipitate design based on the addition of boron to approximately 0.01 wt% and decreasing the N content to lowest possible value was suggested by the National Institute for Materials Science (NIMS) to suppress/hinder strain-induced coarsening of M(C,N) carbonitrides and M 23 C 6 carbides [1,9,[22][23][24]. The creep strength of these steels is controlled by coarsening of M 23 C 6 carbides located on the lath boundaries, since the dispersion of M(C,N) carbonitrides retains virtually unchanged after creep [12,16,25,26].…”

Section: Introductionmentioning

confidence: 99%

Coarsening of Laves phase and creep behaviour of a Re-containing 10% Cr-3% Co-3% W steel

Fedoseeva

Nikitin

Dudova

et al. 2021

Materials Science and Engineering: A

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Effect of W–Mo balance on long-term creep life of 9Cr steel

Cited by 13 publications

References 13 publications

Effect of Alloying on the Nucleation and Growth of Laves Phase in the 9–10%Cr-3%Co Martensitic Steels during Creep

Effect of Alloying on the Nucleation and Growth of Laves Phase in the 9–10%Cr-3%Co Martensitic Steels during Creep

Variations in Creep Performance of P92 Steel Within Its Composition Range: Influence of N Solubility

Coarsening of Laves phase and creep behaviour of a Re-containing 10% Cr-3% Co-3% W steel

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