Effects of Simulated Microstructure on the Creep Rupture of the Modified 9Cr-1Mo Steel

Hsiao, Tsung–Yuan; Chen, Tai-Cheng; Jeng, Sheng-Long; Chung, Tien-Jung; Tsay, L.W.

doi:10.1007/s11665-016-2270-6

Cited by 14 publications

(20 citation statements)

References 35 publications

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“…The lath morphology was obscure in two PT samples, especially in the 940NT-PT one. In previous work [8,9], the ICHAZ in the as-welded condition comprises of fine ferrite subgrains and fresh fine martensite, indicating a refined structure. Lath martensite in the PT samples was too fine to be revealed in the SEM observation.…”

Section: Resultsmentioning

confidence: 83%

“…The SEM micrograph ( Figure 4c) revealed numerous fresh nucleated fine grains in the 1060NT-PT sample. The lath structure could hardly be observed in the 1060NT-PT sample, which was partially related to the extremely fine martensite [9]. The IPF map ( Figure 4d) displayed some local areas, indicated by the arrow, which were oriented in almost the same direction but divided by sub-boundaries.…”

Section: Resultsmentioning

confidence: 97%

“…The coexistence of fresh refined lath martensite with a high dislocation density and carbide-free ferrite subgrains caused incomplete hardening of the as-simulated PT or ICHAZ specimens [9]. In the as-simulated condition, most M23C6 carbides heated to slightly below the AC3 temperature dissolved into the matrix, and only few residual carbides remained [9]. After tempering, carbides precipitated mainly along lath boundaries and in ferrite subgrains.…”

Section: Resultsmentioning

confidence: 99%

“…The A C1 , A C3 , M s , and M f temperatures determined by a dilatometer in this work at heating and cooling rates of 15 • C/sec were 870, 915, 425, and 258 • C, respectively. The A C1 and A C3 temperatures of T91 and T92 steels will moderately increase with increasing the heating rates [9,20]. The in situ martensitic transformation of 201 SS under straining can be determined by synchrotron X-ray [21].…”

Section: Resultsmentioning

confidence: 99%

“…Heating around the A C1 of Gr.91 steel may result in no austenite formation. Short-time over-tempering causes the recovery of dislocations, break-down of the lath structure, polygonization, and carbide spheroidizing as well as coarsening [9]. Premature failure of 9-12 Cr creep-strength-enhanced ferritic steel welds after long-term service at elevated temperature is known as Type IV cracking [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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As-received Gr.91 steel tube was normalized at either 940 or 1060 • C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 • C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Shiue

et al. 2018

Metals

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Influence of the Evolution of 9CrMoCoB Steel Precipitates on the Microstructure and Mechanical Properties during High-Temperature Aging

Kuang

Cheng

et al. 2021

J. of Materi Eng and Perform

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In this study, the short-term aging was carried out to reveal the evolution of precipitates and mechanical properties of heat resistant 9CrMoCoB steel during the early creep, replacing the conventional creeping. The tempered martensite lath structure (TMLS) and precipitates were observed in the as-aged 9CrMoCoB steel. TMLS in the matrix underwent a transition to the polygonal ferrite after aging only for 300 h. In comparison, the mean diameter of the precipitates increased from 183 to 267 nm after aging at 650 °C for 300 h. Also, the mean diameter of the precipitates increased from 183 to 302 nm at 700 °C. The room-temperature and high-temperature strength of 9CrMoCoB steel decreased after high-temperature aging, which may be mainly due to precipitates coarsening. Many M23C6 phases precipitate in the prior austenite grain boundary (PAGB) and lath boundary. After aging 100 h, TMLS transformed into polygonal ferrite, and the size of the precipitate at the subgrain boundary was about 100 nm, while after 300 h of high-temperature aging, large precipitates appear (400 nm) in the matrix. After 200 h of high-temperature aging, the obvious growth of precipitates on the PAGB and lath boundary weakens the pinning effect on the PAGB and martensite lath boundary and accelerates the transformation of microstructure and mechanical properties.

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Probing True Microstructure-Hardening Relationship in Simulated Heat Affected Zone of P91B Steels

Ахтар

Khajuria

2019

Metallogr. Microstruct. Anal.

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Effects of Simulated Microstructure on the Creep Rupture of the Modified 9Cr-1Mo Steel

Cited by 14 publications

References 35 publications

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Influence of the Evolution of 9CrMoCoB Steel Precipitates on the Microstructure and Mechanical Properties during High-Temperature Aging

Probing True Microstructure-Hardening Relationship in Simulated Heat Affected Zone of P91B Steels

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