The effect of phase parameter variation on hardness of P91 components after service exposures at 530–550 °C

Peng, Zhiwei; Liu, S.; Yang, Chao; Chen, F.Y.; Peng, Fangfang

doi:10.1016/j.actamat.2017.10.010

Cited by 23 publications

(3 citation statements)

References 61 publications

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“…Upon steadystate and tertiary creep the hardness continuously decreases to a value of about 220 HB. In contrast, the formation of subgrain structure during creep in the 3 wt% Co modified P92-type steel has been reported leading to a hardness drop down to 190 HB [12,16,[45][46][47]. Therefore, the transformation of TMLS to subgrain structure is not critically important for the softening of the present steel.…”

Section: Creep/aging Softeningmentioning

confidence: 85%

“…Second, these carbides precipitate under tempering with a high V content of 1.6 at%. Such high none-equilibrium content of V in M 23 C 6 -type carbides has been sometimes observed and attributed to transformation of V-rich (V,Nb)(C,N) carbonitrides into Z-phase leading to an increase of V in solid solution during long-term aging of 11%Cr steels with ≥ 0.05 wt%N [19,20,44,45]. However, the present steel contains low N content and V depletes from solid solution in the form of M 23 C 6 -type carbides, mainly, under tempering.…”

Section: Dispersed Particlesmentioning

confidence: 99%

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Creep behavior and microstructural evolution of a 9%Cr steel with high B and low N contents

Tkachev

Belyakov

Kaibyshev

2018

Materials Science and Engineering: A

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A B S T R A C TThe creep behavior of a 3%Co modified P92-type steel with high content of boron and low content of nitrogen was studied. The precipitation of Laves phase at lath boundaries provides a rapid decrease in the strain rate during transient creep. The finely dispersed (V,Nb)(C,N) carbonitrides uniformly distributed throughout and M 23 C 6 carbides located at various boundaries/subboundaries result in extended steady-state creep. Gradual coarsening and an increase in the volume fraction of M 23 C 6 carbides as well as coarsening of Laves phase particles is accompanied by an increase in the lath size during the steady-state creep. The coarsening of lath structure that is assisted by the dissolution of Laves phase particles at lath boundaries during steady-state creep leads to the onset of tertiary creep with a highly accelerated rate. The well-developed subgrain structure is observed in the ruptured samples, whereas the distance between high-angle boundaries does not change during the creep.

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Section: Creep/aging Softeningmentioning

confidence: 85%

Section: Dispersed Particlesmentioning

confidence: 99%

Creep behavior and microstructural evolution of a 9%Cr steel with high B and low N contents

Tkachev

Belyakov

Kaibyshev

2018

Materials Science and Engineering: A

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“…At high temperatures, M 23 C 6 and MX carbides become coarse. The coarsening mechanism of the two precipitates conforms to Oswald ripening, i.e., small particles dissolve and large particles coarsen [75][76]. Oswald ripening significantly decreases the amount of precipitates and increases the size of precipitates, reducing the strengthening effect of the precipitates (Eqs.…”

Section: Thermal Stability Of Precipitatesmentioning

confidence: 99%

Strengthening mechanisms of reduced activation ferritic/martensitic steels: A review

Zhou

Shen

Jia

2021

Int J Miner Metall Mater

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This review summarizes the strengthening mechanisms of reduced activation ferritic/martensitic (RAFM) steels. High-angle grain boundaries, subgrain boundaries, nano-sized M 23 C 6 , and MX carbide precipitates effectively hinder dislocation motion and increase high-temperature strength. M 23 C 6 carbides are easily coarsened under high temperatures, thereby weakening their ability to block dislocations. Creep properties are improved through the reduction of M 23 C 6 carbides. Thus, the loss of strength must be compensated by other strengthening mechanisms. This review also outlines the recent progress in the development of RAFM steels. Oxide dispersion-strengthened steels prevent M 23 C 6 precipitation by reducing C content to increase creep life and introduce a high density of nano-sized oxide precipitates to offset the reduced strength. Severe plastic deformation methods can substantially refine subgrains and MX carbides in the steel. The thermal deformation strengthening of RAFM steels mainly relies on thermo-mechanical treatment to increase the MX carbide and subgrain boundaries. This procedure increases the creep life of TMT(thermo-mechanical treatment) 9Cr-1W-0.06Ta steel by ~20 times compared with those of F82H and Eurofer 97 steels under 550°C/260 MPa.

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Effect of Tempering Temperature on Microstructure Evolution and Hardness of 9Cr1. 5Mo1CoB(FB2) Steel

Zhang

Shen

et al. 2021

steel research int.

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The microstructure evolution and hardness variation of FB2 steel influenced by tempering are investigated. The results show that water‐cooling from 1100 °C produces lathy martensite microstructure. After tempering at 500 °C, the steel exhibits a martensite structure with 4.2% needle‐like Fe3C particles. The (Cr, Mo)2C and Cr‐rich M7C3 particles are detected in the sample tempered at 570 °CAs the tempering temperature enhances from 620 to 700 °C the (Cr, Mo)2C and Cr‐rich M7C3 in the matrix are replaced by Cr‐rich M23C6. Besides, the (V, Nb)C particles are identified in samples tempered above 620 °C. Thus, the evolution of carbides in FB2 steel during tempering can be summarized as: Fe3C→(Cr, Mo)2C + Cr‐rich M7C3→(Cr, Mo)2C + Cr‐rich M7C3 + Cr‐rich M23C6→Cr‐rich M23C6. Furthermore, the results suggest that M3C, M2C + M7C3, M23C6, and MX have high reaction rates at 500, 570, 620, and 700 °C respectively. In addition, the dislocation density reduces from 6.8 × 1014 m−2 to 2.1 × 1014 m−2, and the volume fraction of carbides increases from 4.2% to 12.6% with increasing temperatures from 500 to 700 °C leading to hardness decrease from 485 to 284 Hv. Finally, the quantitative relationship between the hardness and microstructure evolution during tempering is discussed.

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The effect of phase parameter variation on hardness of P91 components after service exposures at 530–550 °C

Cited by 23 publications

References 61 publications

Creep behavior and microstructural evolution of a 9%Cr steel with high B and low N contents

Creep behavior and microstructural evolution of a 9%Cr steel with high B and low N contents

Strengthening mechanisms of reduced activation ferritic/martensitic steels: A review

Effect of Tempering Temperature on Microstructure Evolution and Hardness of 9Cr1. 5Mo1CoB(FB2) Steel

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