Microstructure and creep properties of high Cr resisting weld metal alloyed with Co

Wang, Xue; Zhan, Liang-fei; Qian-gang, Pan; Liu, Zhijun; Hong, Liu; Yong-shun, Tao

doi:10.1631/jzus.a1000215

Cited by 5 publications

(1 citation statement)

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“…Owing to its importance, studies are continuously focused on ultra-supercritical steel materials (Ref 1, 2). During the end of the last century, the European research institute (Ref 3, 4) has developed 9CrMoCoB steel (Ref 5-7) based on P92 steel (Ref 8-10) by increasing the content of B ( Ref 11,12) and introducing Co (Ref [13][14][15].The main steam pipelines of power plants in the United States target continuous use of 100,000 h by utilizing steam at 100 MPa ( Ref 16,17). After the creep test for 85,000 h, it has been found that 9CrMoCoB steel has good creep resistance, and hence it is considered a key material for thermal power plant unit castings (Ref 3).…”

Section: Introductionmentioning

confidence: 99%

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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