Critical cleavage fracture stress characterization of A508 nuclear pressure vessel steels

Wu, Sujuan; Jin, Hui-Jin; Sun, Y. K.; Cao, Luowei

doi:10.1016/j.ijpvp.2014.08.003

Cited by 18 publications

(9 citation statements)

References 22 publications

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“…Thus, CPI were used here to characterize precipitation for a matrix of advanced alloys with compositions that extend beyond the typical range the current RPV steels. The focus is on developing so-called super-clean steels, with very high Ni contents (> 3 wt.%), that have superior unirradiated properties [11][12][13][14][15][16]. However, high Ni levels lead to 4 enormous irradiation hardening and embrittlement in RPV steels with typical Mn and Si contents [11].…”

Section: Introduction Background and Objectivementioning

confidence: 99%

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

Almirall

Wells

Yamamoto

et al. 2020

Journal of Nuclear Materials

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Nuclear reactor lifetimes may be limited by nano-scale Cu-Mn-Ni-Si precipitates (CRPs and MNSPs) that form under neutron irradiation (NI) of pressure vessel (RPV) steels, resulting in hardening and ductile to brittle transition temperature increases (embrittlement). Physical models of embrittlement must be based on characterization of precipitation as a function of the combination of metallurgical and irradiation variables. Here we focus on rapid and convenient charged particle irradiations (CPI) to both: a) compare to precipitates formed in NI; and, b) use CPI to efficiently explore precipitation in steels with a very wide range of compositions. Atom probe tomography (APT) comparisons show NI and CPI for similar bulk steel solute contents yield nearly the same precipitate compositions, albeit with some differences in their number density, size and volume fraction (f) dose (dpa) dependence. However, the overall precipitate evolutions are very similar. Advanced high Ni (> 3 wt.%) RPV steels, with superior unirradiated properties, were also investigated at high CPI dpa. For typical Mn contents, MNSPs have Ni16Mn6Si7 or Ni3Mn2Si phase type compositions, with f values that are close to the equilibrium phase separated values. However, in steels with very low Mn and high Ni, Ni2-3Si silicide phase type precipitate compositions are observed; and when Ni is low, the precipitate compositions are close to the MnSi phase field. Low Mn significantly reduces, but does not eliminate, precipitation in high Ni steels. A comparison of dispersed barrier model predictions with measured hardening data suggests that the Ni-Si dominated precipitates are weaker dislocation obstacles than the G phase type MNSPs.

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Section: Introduction Background and Objectivementioning

confidence: 99%

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

Almirall

Wells

Yamamoto

et al. 2020

Journal of Nuclear Materials

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“…An immediate practical motivation for this work is that such high Ni steels have outstanding unirradiated strength and toughness properties [32][33][34][35][36]. As a specific example, the A508 Gr.…”

Section: Introductionmentioning

confidence: 99%

Precipitation and hardening in irradiated low alloy steels with a wide range of Ni and Mn compositions

et al. 2019

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Mn-Ni-Si intermetallic precipitates (MNSPs) that are observed in some Fe-based alloys following thermal aging and irradiation are of considerable scientific and technical interest. For example, large volume fractions (f) of MNSPs form in reactor pressure vessel low alloy steels irradiated to high fluence, resulting in severe hardening induced embrittlement. Nine compositionally-tailored small heats of low Cu RPV-type steels, with an unusually wide range of dissolved Mn (0.06-1.34 at.%) and Ni (0.19-3.50 at.%) contents, were irradiated at ≈ 290°C to ≈ 1.4x10 20 n/cm 2 at an accelerated test reactor flux of ≈ 3.6x10 12 n/cm 2 -s (E > 1 MeV). Atom probe tomography shows Mn-Ni interactions play the dominant role in determining the MNSP f, which correlates well with irradiation hardening. The wide range of alloy compositions results in corresponding variations in precipitates chemistries that are reasonably similar to various phases in the Mn-Ni-Si projection of the Fe based quaternary. Notably, f scales with ≈ Ni 1.6 Mn 0.8 . Thus f is modest even in advanced high 3.5 at.% Ni steels at very low Mn (Mn starvation); in this case Nisilicide phase type compositions are observed.

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“…For martensite laths, where a high dislocation density may cause a brittle fracture without any plastic deformation, some researchers accept a γ p value of between 7-9 J m −2 [21,22] while others increase this value up to 14 J m −2 [23]. On the other hand, it has also been suggested that the cleavage fracture stress σ f could be used as an engineering notch toughness parameter for specific materials to assess the integrity of structures with notch defects [24].…”

Section: Griffith's Equation Application To Cleavage Fracturementioning

confidence: 99%

Measurement of martensitic packet size by EBSD in the high strength steel X38CrMoV5-1 and estimation of its influence on cleavage fracture

Pastor¹,

Vallés²,

Zubiaur³

et al. 2020

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The crystallographic packet or microstructural unit was determined with 15 • and 5 • boundary grain misorientations in a quenched and tempered X38CrMoV5-1 steel, yielding results of 0.68 and 0.59 µm, respectively. Though both values are similar, the latter has been taken as the best to calculate the effective surface energy of cleavage fracture, γp, leading to a value of 15.8 J m −2. Thus it is demonstrated that the microstructural unit controlling crack propagation is that determined by EBSD with a 5 • misorientation angle. Other structural parameters, like the parent austenite grain size and the morphological martensitic packet, have been ruled out.

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Critical cleavage fracture stress characterization of A508 nuclear pressure vessel steels

Cited by 18 publications

References 22 publications

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

On the use of charged particles to characterize precipitation in irradiated reactor pressure vessel steels with a wide range of compositions

Precipitation and hardening in irradiated low alloy steels with a wide range of Ni and Mn compositions

Measurement of martensitic packet size by EBSD in the high strength steel X38CrMoV5-1 and estimation of its influence on cleavage fracture

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