Effect of short-term aging on the impact toughness of advanced 10% Cr steel

Published on Nov 19, 2019
· DOI :10.1063/1.5132098
R. Mishnev9
Estimated H-index: 9
,
Nadezhda Dudova13
Estimated H-index: 13
,
Rustam Kaibyshev60
Estimated H-index: 60
Sources
Abstract
The effect of short-term aging (100 h) at 650°C on the temperature dependence of impact toughness and fracture behavior of advanced 10% Cr steel with low N and high B contents was studied. The steel in tempered condition exhibits the ductile-brittle transition temperature (DBTT) of ∼10°C and the Charpy V-notch impact energy of 240 J/cm2 at a temperature of 20°C. Aging for 100 h at 650°C leads to the increase in the DBTT to 35°C and decrease in the impact toughness at 20°C to 90 J/cm2. Effect of the fine (up to 100 nm) Laves phase particles precipitated at lath/grain boundaries on the impact toughness is analyzed. The Laves phase particles serve as additional nucleation sites for microcracks/voids facilitating unstable crack propagation. This is the main reason for decreasing the stable crack propagation energy and impact toughness of the steel.
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References8
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#1J. Borisova (Belgorod State University)H-Index: 1
#2Valeriy Dudko (Belgorod State University)H-Index: 10
Last. Rustam Kaibyshev (Belgorod State University)H-Index: 60
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The impact toughness of a martensitic 12 Cr-0.6 Mo-2.2 W-4 Co-0.8 Cu-VNb (in wt pct) steel subjected to tempering at 770 °C for 3 hours and aging at 650 °C for 643 hours was examined in the temperature range of − 20 to 250 °C. The steel in the tempered condition exhibits a ductile-brittle transition temperature (DBTT) of 41 °C and a Charpy V-notch impact energy of 100 J/cm2 at a temperature of 20 °C. The tempered steel becomes completely brittle at 0 °C when the absorbed energy falls to 8 J/cm2....
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#1R. Mishnev (Belgorod State University)H-Index: 9
#2Nadezhda Dudova (Belgorod State University)H-Index: 13
Last. Rustam Kaibyshev (Belgorod State University)H-Index: 60
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Abstract The effect of temperature on the impact toughness and fracture behavior of a 10% Cr-2% W-0.7% Mo-3% Co-0.05% Nb-0.2% V-0.008% B-0.003% N (all in wt%) steel was studied. The ductile-brittle transition (DBT) occurs at 10 °C. At the DBT temperature (DBTT), the onset of unstable crack propagation occurs at the maximum load. The embrittlement is attributed to the onset of unstable crack propagation at stresses below the general yielding. A decrease in nitrogen content and an increase in boro...
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#1R. Mishnev (Belgorod State University)H-Index: 9
#2Nadezhda Dudova (Belgorod State University)H-Index: 13
Last. Rustam Kaibyshev (Belgorod State University)H-Index: 60
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Abstract The microstructural evolution and the dispersion of secondary phases were studied in a low-nitrogen 10%Cr martensitic steel with 3% Co and 0.008% B additives at 650 °C under an applied stress of 140 MPa. It was demonstrated that the superior creep strength of this steel can be attributed to the high resistance of M 23 C 6 -type carbides and Nb-rich MX carbonitrides against coarsening, resulting in a stable of the tempered martensite lath structure (TMLS) under short-term creep condition...
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#1Fujio Abe (National Institute for Materials Science)H-Index: 52
ABSTRACT Materials-development projects for advanced ultra-supercritical (A-USC) power plants with steam temperatures of 700 °C and above have been performed in order to achieve high efficiency and low CO2 emissions in Europe, the US, Japan, and recently in China and India as well. These projects involve the replacement of martensitic 9%−12% Cr steels with nickel (Ni)-base alloys for the highest temperature boiler and turbine components in order to provide sufficient creep strength at 700°C and ...
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#1Zhong Wanli (EPRI: Electric Power Research Institute)H-Index: 2
#2Wang Wei (EPRI: Electric Power Research Institute)H-Index: 3
Last. Ke Yang (CAS: Chinese Academy of Sciences)H-Index: 50
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Abstract Laves phase has been widely accepted to cause the impact brittleness of 9–12Cr martensitic heat-resistant steels after long time aging at elevated temperatures. However, in the present research, the impact toughness of the already brittle P92 steel aged at 600 °C for 2035 h could be restored to the original level by reheating at 700 °C for 1 h, with Laves phase barely changed. This interesting result strongly indicated that the presence of Laves phase might not be the real reason for th...
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Last. Wei Liu (THU: Tsinghua University)H-Index: 26
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#1Xue Hu (CAS: Chinese Academy of Sciences)H-Index: 7
#2Lixin Huang (CAS: Chinese Academy of Sciences)H-Index: 6
Last. Ke Yang (CAS: Chinese Academy of Sciences)H-Index: 50
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Abstract The China Low Activation Martensitic (CLAM) steel has been developed as a candidate structural material for future fusion reactors. It is essential to investigate the evolution of microstructure and changes of mechanical properties of CLAM steel during thermal exposure. In this study, the long-term thermal aging of the CLAM steel has been carried out in air at 600 °C and 650 °C for 1100 h, 3000 h and 5000 h. The microstructural evolution with aging time was studied, including characteri...
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AbstractThe research and development project of National Institute for Materials Science (NIMS) for advanced ferritic heat resistant steels for 650°C ultra super critical (USC) plants, revealed that the addition of >0·01 mass% boron to a 0·08C–9Cr–3W–3Co–V–Nb–,0·003N steel remarkably improves the long term creep strength. Boron enriched in M23C6 carbides near prior austenite grain boundaries suppresses the coarsening of carbides during creep deformation, leading to excellent microstructural stab...
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