Alloy Design of Martensitic 9Cr‐Boron Steel for A‐USC Boiler at 650°C – Beyond Grades 91, 92 and 122

Abe, Fujio; Tabuchi, Masaaki; Tsukamoto, Shiro

doi:10.1002/9781119027973.ch13

Cited by 3 publications

(6 citation statements)

References 8 publications

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“…10c). Compared to other 9Cr creep resistant steels (P92 and MarBN2) [20][21][22], not only the base material but also the welded samples show very good creep properties, Fig. 11.…”

Section: Creep Testsmentioning

confidence: 97%

“…Dye penetration testing (PT) prior to Fig. 11 Creep testing results for NPM1 base material and EBW cross-welds tested at 650°C compared to corresponding MarBN2 base material, GMAW cross-welds, and gradeP92 base material and cross-welds [20][21][22] creep investigation indicated the existence of open microfissures within the fusion zone of the creep samples, Fig. 10 a and b).…”

Section: Creep Testsmentioning

confidence: 99%

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Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

et al. 2019

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Martensitic 9-12% chromium steel is a favored material group for critical components in thermal power plants. However, during welding of these steels, a fine-grained zone is formed within the heat-affected zone, which is subject to type IV cracking during creep exposure. Due to the MarBN alloying concept, which is characterized by the controlled addition of boron and nitrogen, the formation of the fine-grained heat-affected zone can be suppressed and the minimum creep rate can be significantly decreased. First, EB welding studies were carried out, and the influence of the process parameters on the weld seam quality, geometry, microstructure, and hardness was investigated. However, independent of the used parameters, microfissures were detected within the fusion zone of the welds. To reduce the hot crack formation within the fusion zone, focus wobbling was used. Results showed an improvement with respect to accumulated number and length of the microfissures, but the formation could not completely be prevented. Despite this problem, the mechanical properties of joint welds were determined and creep investigations were conducted. Results showed that the existence of microfissures within the fusion zone has no major influence on the mechanical and the creep properties.

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“…10c). Compared to other 9Cr creep resistant steels (P92 and MarBN2) [20][21][22], not only the base material but also the welded samples show very good creep properties, Fig. 11.…”

Section: Creep Testsmentioning

confidence: 97%

Section: Creep Testsmentioning

confidence: 99%

Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

et al. 2019

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“…To meet the stringent requirements for high reliability and long-term service, 9% Cr steels are commonly employed due to their exceptional properties including high-temperature strength, creep resistance, good thermal conductivity, low coefficient of thermal expansion, as well as high corrosion and oxidation resistance. [1][2][3][4][5][6] A novel heat-resistant steel, 9Cr3W3Co, has recently been developed to achieve higher thermal efficiency. [7][8][9][10] This steel exhibits a tempered martensite ferritic microstructure comprising numerous laths, dislocations, M 23 C 6 precipitates along with MX ones.…”

Section: Introductionmentioning

confidence: 99%

Comparison in microstructure, mechanical properties, and fatigue behavior of 9Cr3W3Co turbine rotor steel and its welded joint

Mai,

Liu,

Chen

et al. 2024

Fatigue Fract Eng Mat Struct

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The microstructure, mechanical properties, and high/very‐high cycle fatigue behaviors of 9Cr3W3Co turbine rotor steel and its welded joint were investigated. The welded nugget zone (WNZ) exhibited the highest microhardness value, followed by the heat‐affected zone (HAZ), while the base material (BM) showed the lowest hardness value. The WNZ exhibited a higher yield strength compared to the BM with reduced elongation, while maintaining similar ultimate tensile strength. The fatigue strength of the BM at 5 × 107 cycles is roughly 53.7% of the yield strength, whereas that of the WNZ increases to approximately 55.0%. In comparison to the fatigue strength of the BM at 5 × 107 cycles, the WNZ exhibits a notable increase of 10.5%. Smaller grain size and higher dislocation density were observed in the WNZ, which contributed to improved microhardness, yield strength, and fatigue resistance through grain boundary strengthening and dislocation hardening.

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“…With the aim of increasing base material creep strength and suppressing the formation of detrimental fine grained HAZ a new alloy concept, called martensitic 9Cr steel strengthened by boron and nitrogen (MARBN), was developed. 10,11,[13][14][15][16][17] The idea was that without these fine grains, which are not fully pinned by precipitates, the formation of creep damage by Type IV cracking could be avoided. To eliminate these fine grains a certain balance between boron and nitrogen is necessary.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of creep damage in advanced martensitic chromium steel weldments using synchrotron X-ray micro-tomography and EBSD

Schlacher¹,

Pelzmann²,

Béal³

et al. 2015

Materials Science and Technology

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In recent years, a design concept for the stabilisation of the microstructure by addition of boron and nitrogen was developed. This so called martensitic boron-nitrogen strengthened steel (MARBN) combines boron strengthening by solid solution with precipitation strengthening by finely dispersed nitrides. Welded joints of MARBN steels showed no formation of a uniform fine grained region in the heat affected zone (HAZ) which is in general highly susceptible to Type IV cracking. In this work, the crossweld creep strength of a newly developed MARBN steel was analysed and the evolution of damage was investigated using synchrotron microtomography supported by electron microscopy. Three-dimensional (3D) reconstructions of the tested samples together with electron backscatter diffraction investigations revealed an intense void formation in a restricted area along small grains at prior austenite grain boundaries in the HAZ as the main reason for premature creep failures in the HAZ of welded joints.

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Alloy Design of Martensitic 9Cr‐Boron Steel for A‐USC Boiler at 650°C – Beyond Grades 91, 92 and 122

Cited by 3 publications

References 8 publications

Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

Influence of the focus wobbling technique on the integrity and the properties of electron beam welded MarBN steel

Comparison in microstructure, mechanical properties, and fatigue behavior of 9Cr3W3Co turbine rotor steel and its welded joint

Investigation of creep damage in advanced martensitic chromium steel weldments using synchrotron X-ray micro-tomography and EBSD

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