Evolution of Lath Substructure and Internal Stresses in a 9% Cr Steel during Creep

Dudko, Valeriy; Belyakov, Andrey; Kaibyshev, Rustam

doi:10.2355/isijinternational.isijint-2016-334

Cited by 41 publications

(72 citation statements)

References 47 publications

(139 reference statements)

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“…The present steel is characterized by an improved creep resistance. The time to rupture was 4883 h, which is more than 2.5 times longer than that in other P92-type steels under the same creep conditions [4,5,8,29]. Three distinctive creep stages, i.e.…”

Section: Creep Behaviormentioning

confidence: 82%

“…3c) are indicative of retaining internal elastic stresses. Thus, the mobile lattice dislocations are trapped by low-angle lath boundaries [7,8] that may lead to increasing their misorientations.…”

Section: Microstructural Evolutionmentioning

confidence: 99%

“…The solid solution strengthening is provided by such interstitial solutes as carbon and nitrogen and substitutional solutes of W, Mo and Cr. The dispersion strengthening is provided by numerous nanoscale (V,Nb)(C,N) carbonitrides precipitated in ferrite matrix [1][2][3][4] and M 23 C 6 carbides located at any boundaries/subboundaries [7][8][9]. The long-range internal elastic stress fields originated from lath boundaries and lattice dislocations also contribute to superior creep resistance of these steels [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…A degradation of TMLS under creep reduces the creep strength and leads to the creep strength breakdown that strongly diminishes the long-term creep strength [11][12][13][14][15][16][17]. The finely dispersed carbonitrides and boundary carbides play a key role in stability of TMLS under creep condition [1][2][3][4][8][9][10][11][12][13][14]. The M 23 C 6 carbides located at lath boundaries exert a high Zener drag force and play a major role in the stability of TMLS under creep conditions [4,[11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…However, these dispersoids slows down the knitting reaction between the dislocations and lath boundaries. This reaction leads to transformation of the lath boundaries, which are irregular dislocation networks exhibiting long-range stress fields, into sub-boundaries, thereby relieving the internal stress fields [8,14,18].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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 Behaviormentioning

confidence: 82%

Section: Microstructural Evolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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The Coupling Effect of Hierarchical Structures and MN‐Type Precipitates on the Creep Resistance for the High N Heat‐Resistant Martensitic Steel

Shi

Sun

Ning

et al. 2022

steel research int.

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Microstructure of the high nitrogen heat‐resistant martensitic steel (HNHM) crept using 140–170 MPa loading stresses at 923 K is investigated in correlation with creep lifetime and creep rupture strength. Upon creep deformation, both recrystallized grains and the preexisted hierarchical structures grow via strain‐induced boundaries migration (SIBM) induce the degradation of strengthening. For preexisted hierarchical structures in HNHM, martensitic packets and blocks are more inclined to form at higher stresses (170 MPa), causing the degradation of strength, while laths retain easily at lower stresses (140–155 MPa), retarding the creep damage. Additionally, under all stresses and upon 923 K, the highly stabilized MN precipitates not only pin the hierarchical structural boundaries effectively, but also act as the core for the nucleation of Laves, realizing strengthening. The findings elucidate the coupling contribution of hierarchical structures and MN‐type precipitates on the creep strengthening for HNHMs, challenging the common viewpoint that the coupling coarsening of lath and precipitates dominates the degradation of strengthening, and thus, deepens the understanding of the creep resistance of the HNHM and provides the first insights into obtaining reliable predicted creep life of the novel HNHMs.

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Ferritic–Martensitic Steels in Power Industry: Microstructure, Degradation Mechanism, and Strengthening Methods

Jiang,

Huang,

Feng

et al. 2024

steel research int.

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Ferritic–martensitic (F–M) steels are widely used for high‐temperature pressure vessels and reactor cladding structures in power plants. The high operating temperatures and pressures, as well as the radiation environment, significantly challenge the mechanical stability of these steels. Here, the degradation mechanisms in F–M steels during creep and thermal aging under these harsh environments are reviewed. The exceptional mechanical properties of F–M steels are mainly attributed to their well‐constructed microstructures and chemical compositions. Microstructural barriers such as dislocations, solid solution atoms, and precipitates play key roles in resisting degradation. During the long‐term service, the microstructures undergo gradual evolution, resulting in a deterioration of mechanical properties at the macrolevel. In addition to the degradation mechanisms, some recent advancements in strengthening methods, including microalloying strengthening, thermomechanical treatment (TMT), and oxide dispersion strengthening, are summarized, aimed at the development of next‐generation F–M steels. The strengthening of the F–M steels is mainly achieved by enhancing the thermal stability of their microstructures. Insight into both the deterioration mechanisms and strengthening methods of F–M steels may pave the way for new approaches in developing high‐performance steels for applications in next‐generation power plants operating at ultrahigh operating temperatures and pressures.

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Evolution of Lath Substructure and Internal Stresses in a 9% Cr Steel during Creep

Cited by 41 publications

References 47 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

The Coupling Effect of Hierarchical Structures and MN‐Type Precipitates on the Creep Resistance for the High N Heat‐Resistant Martensitic Steel

Ferritic–Martensitic Steels in Power Industry: Microstructure, Degradation Mechanism, and Strengthening Methods

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