Creep behavior and microstructure evaluation of welded joint in dissimilar modified 9Cr–1Mo steels

Liu, Wen; Liu, Xia; Lu, Fenggui; Tang, Xinhua; Cui, Haichao; Gao, Yulai

doi:10.1016/j.msea.2015.07.068

Cited by 67 publications

(17 citation statements)

References 32 publications

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“…The decrease of hardness is due to the lower dislocation density and coarsening of carbides, 44,45 and it can be inferred that lower dislocation density and depletion of solid-solution elements solubility result in the softening behaviour during the cyclic loading. The decrease of hardness is due to the lower dislocation density and coarsening of carbides, 44,45 and it can be inferred that lower dislocation density and depletion of solid-solution elements solubility result in the softening behaviour during the cyclic loading.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

“…(2) the solid-solution strengthening elements such as Cr and Mo; and (3) the precipitated strengthening carbides such as M 23 C 6 at grain/lath boundaries and MX in the grains. The decrease of hardness is due to the lower dislocation density and coarsening of carbides, 44,45 and it can be inferred that lower dislocation density and depletion of solid-solution elements solubility result in the softening behaviour during the cyclic loading. As for the as-received sample, the hardness at the grain boundary is higher than that in the matrix, which is mainly due to the precipitated carbides at boundaries.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

“…Hardness and creep property are the comprehensive results of matrix, grain boundary and second phase. 44 With prolonged service time, the separation and coarsening of carbides at a grain boundary and surface active elements such as P, segregation weakens the strength of the grain boundary, 46 and the recovery of dislocation density all leads to the degradation of the material. It is known that the grain boundary is likely to be the main strengthening factor under high stress with significant plastic deformation.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

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Cyclic behaviour of 12% Cr ferritic‐martensitic steel upon long‐term on‐site service in power plants

Zhang

Schmauder

2016

Fatigue Fract Eng Mat Struct

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The strain‐controlled and stress‐controlled low‐cycle fatigue behaviour of served 12% Cr ferritic–martensitic steel is conducted at room temperature. Continuous softening is observed at both control modes, and the fitting results show that the fatigue properties of 12% Cr steel are not reduced significantly after 230 000 h service at 550 °C/13.7 MPa. Scanning electron microscopy has been employed to investigate the microstructure evolution after long‐term service. It is proved that the decomposition of martensite laths structure and the coarsening of carbides at grain/lath boundaries are the main reasons why the pipe bursts after 180 000 h service at 550 °C/17.1 MPa. The fracture under both control modes has been observed by using scanning electron microscopy, and it indicates coarse carbides along grain/lath boundaries are favourable sites for micro‐crack nucleation and the secondary cracks along the fatigue striations are formed by the connection of micro‐cracks nucleated during fatigue behaviour.

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Section: Microstructure Evolutionmentioning

confidence: 99%

Section: Microstructure Evolutionmentioning

confidence: 99%

Section: Microstructure Evolutionmentioning

confidence: 99%

See 1 more Smart Citation

Cyclic behaviour of 12% Cr ferritic‐martensitic steel upon long‐term on‐site service in power plants

Zhang

Schmauder

2016

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…To enhance thermal efficiency and reduce carbon dioxide emission, plenty of countries are currently developing the large‐capacity ultra‐supercritical (USC) units . By raising the steam temperature up to 600°C, the economic efficiency of generating units can be increased remarkably.…”

Section: Introductionmentioning

confidence: 99%

“…To enhance thermal efficiency and reduce carbon dioxide emission, plenty of countries are currently developing the large-capacity ultra-supercritical (USC) units. 1 By raising the steam temperature up to 600°C, the economic efficiency of generating units can be increased remarkably. Compared with supercritical units, USC units can afford a 4% to 7% increase in heat efficiency (from 40% to 45%-47%) as well as a 20% to 25% reduction in the carbon dioxide emission.…”

Section: Introductionmentioning

confidence: 99%

Effect of multiaxial stress state on creep damage in ASME T92 welded joint

Wang

et al. 2019

Fatigue Fract Eng Mat Struct

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This study reports the type IV fracture process and the influence of multiaxial stress state in ASME T92 welded joints during creep. The type IV fracture occurs at the fine‐grained heat‐affected zone (ie, FGHAZ), involving void initiation, growth, and coalescence, microcrack occurrence, propagation and extension, and eventual macrocrack with consequent joint failure. The creep damage is not uniformly distributed along the thickness direction in the FGHAZ, and the central part of the welded joint is the most seriously damaged region. The equivalent creep strain is higher at the external surface, but the stress triaxiality is larger in the centre section. Large equivalent creep strain could promote creep void initiation, whereas high hydrostatic pressure and stress triaxiality factor accelerate void growth in the FGHAZ of T92 joints. Besides, reducing groove angle and HAZ width of the joints is recommended to delay the occurrence of type IV cracking because of lower equivalent creep strain and stress triaxiality factor.

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Microstructure Evolution and Mechanical Behaviors of P92 Steel Welded Joint with Repetitive Post Tempering

Wang

Jian

et al. 2023

Adv Eng Mater

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The microstructure evolution and mechanical properties of P92 steel welded joint have been systematically investigated relating to the number of tempering cycles. Martensite laths, M23C6 precipitates, and tiny MX phase have been characterized in P92 base metal (BM). Likewise, the heat‐affected zone (HAZ), fusion zone (FZ), and weld metal (WM) show the similar feature of phase composition to the BM. However, δ‐ferrite patches can be found in FZ. With the increasing number of tempering cycles, the area fraction and average size of M23C6 precipitates gradually increase in HAZ and FZ despite that microstructure has little change. Consequently, the hardness, ultimate tensile strength, and yield strength tend to decrease, while the elongation can be improved in some degree. The reduction in solution strengthening, grain refinement strengthening, and precipitation strengthening is responsible for the strength degeneration of P92 steel welded joint with reduplicative tempering.

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Creep behavior and microstructure evaluation of welded joint in dissimilar modified 9Cr–1Mo steels

Cited by 67 publications

References 32 publications

Cyclic behaviour of 12% Cr ferritic‐martensitic steel upon long‐term on‐site service in power plants

Cyclic behaviour of 12% Cr ferritic‐martensitic steel upon long‐term on‐site service in power plants

Effect of multiaxial stress state on creep damage in ASME T92 welded joint

Microstructure Evolution and Mechanical Behaviors of P92 Steel Welded Joint with Repetitive Post Tempering

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