Separation of Microstructural and Microchemical Effects in Irradiation Assisted Stress Corrosion Cracking using Post-irradiation Annealing

Fukuya, Koji; Nakano, Morihito; Fujii, K.; Torimaru, Tadahiko; Kitsunai, Yuji

doi:10.1080/18811248.2004.9726351

Cited by 51 publications

(19 citation statements)

References 14 publications

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“…IASCC susceptibility, mechanical properties and microstructures of the as-irradiated tube materials were thoroughly examined in the previous studies. 4,13,14) It was confirmed that the tube materials were susceptible to IASCC at 4 dpa and highly susceptible at 35 dpa and that the microstructure mainly consisted of dislocation loops with a diameter of $12 nm and dense small bubbles with well-developed grain boundary segregation of Cr, Ni, Si, and Mo.…”

Section: Methodsmentioning

confidence: 82%

“…Ledge formation and microcracking at grain boundaries were reported in deformed irradiated stainless steels, suggesting that localized deformation is related to grain boundary cracking. 4,7) These previous studies showed the deformation characteristics at doses less than several dpa, where the irradiated materials showed no plastic instability. It is well known that the yield strength saturates at doses near 10 dpa in stainless steels irradiated at approximately 300 C. At doses higher than such level, irradiated stainless steels show extremely low uniform elongation and plastic instability.…”

Section: Introductionmentioning

confidence: 82%

“…[1][2][3] Among these radiation-induced changes, the importance of deformation mode on IASCC has been emphasized. [3][4][5] High-density defect clusters such as dislocation loops produced by neutron irradiation hinder the movement of dislocations. As the dislocation moves, it annihilates the defects on the slip plane, thus opening up a path for subsequent dislocations, which is called a dislocation channel.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Deformation Structure in Highly Irradiated Stainless Steels

Nishioka¹,

Fukuya²,

Fujii³

et al. 2008

J. Nucl. Sci. Technol.

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Surface steps and deformation microstructure in cold-worked SUS316 stainless steels irradiated to 4 and 35 dpa (displacements per atom) were examined after being deformed by uniaxial tensile stress at 320 C at a slow or fast strain rate. Dislocation channeling was the predominant mode of deformation near the surface at the slow strain rate. Twinning was dominant at the fast strain rate whereas twinning and nanotwin formation occurred in the locally stressed area at the slow strain rate. Deformation heterogeneity measured using the spacing of coarse surface steps induced by dislocation channels increased with increasing dose from 4 to 35 dpa. Grain boundary separation occurred when dislocation pileups and high normal stress on the grain boundary plane coexisted, which likely was a precursor of intergranular cracking without any environmental factor.

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Section: Methodsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deformation Structure in Highly Irradiated Stainless Steels

Nishioka¹,

Fukuya²,

Fujii³

et al. 2008

J. Nucl. Sci. Technol.

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“…GB Cr concentration is a key factor for the passivation behavior and oxide characteristics near GBs. (2) IASCC susceptibility appeared at the yield strength of 500-600 MPa and increased with increasing yield strength in both BWR and PWR water conditions [5,294]. CGRs of irradiated SSs were slightly higher than the linear trend seen between CGR and yield strength in non-irradiated CW SSs [295,296].…”

Section: Factors Controlling Iasccmentioning

confidence: 96%

Current understanding of radiation-induced degradation in light water reactor structural materials

Fukuya¹

2013

Journal of Nuclear Science and Technology

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153

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Current phenomenological knowledge and understanding of mechanisms are reviewed for radiation embrittlement of reactor pressure vessel low alloy steels and irradiation assisted stress corrosion cracking of core internals of stainless steels. Accumulated test data of irradiated materials in light water reactors and microscopic analyses by using state-of-the-art techniques such as a three-dimensional atom probe and electron backscatter diffraction have significantly increased knowledge about microstructural features. Characteristics of solute clusters and deformation microstructures and their contributions to macroscopic material property changes have been clarified to a large extent, which provide keys to understand in the degradation mechanisms. However, there are still fundamental research issues that merit study for long-term operation of reactors that requires reliable quantitative prediction of radiation-induced degradation of component materials in low-dose rate high-dose conditions.

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“…3,4) Recent studies suggested that the localized deformation near grain boundaries plays an important role in intergranular cracking and IASCC. 5,6) The spacing and inclination angle of surface steps to the loading direction (hereinafter termed ''step angle'') are representative parameters for characterizing localized plastic deformation. The angular distribution of step angle has been obtained experimentally in previous studies.…”

Section: Introductionmentioning

confidence: 99%

Angular Distribution of Slip Steps by Three-Dimensional Polycrystalline Model for Stainless Steel

Kamaya¹,

Fukuya²,

Kitamura

2009

Journal of Nuclear Science and Technology

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Localized deformation plays an important role in the initiation of irradiation-assisted stress corrosion cracking, and it can be characterized by the spacing and inclination of slip steps observed on the surface. In order to examine the contribution of mechanical factors (stress) to slipping, the angular distribution of slip steps was evaluated by using a three-dimensional polycrystalline model generated by Voronoi tessellation. An elastic finite element analysis was performed to derive the resolved shear stress (RSS) acting on each slip system. Random crystallographic orientations assigned to each grain caused the microstructural inhomogeneity of local stress due to anisotropic elastic properties. The angular distribution obtained was compared with the experimental results observed in irradiated and deformed stainless steel. It was shown that mechanical factors dominate the slipping behavior of the irradiated stainless steel and that not only RSS but also normal stress acting on the slip plane affects the crystallographic slip. The angular distribution was also evaluated from the maximum Schmid factor of individual grains, in which the inhomogeneous local stress was not taken into account. The angular distributions obtained using RSS and the Schmid factor were almost the same. This suggests that the inhomogeneity of local stress negligibly affects the angular distribution of slip steps, although the change in the local stress in the polycrystalline material is significant.

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Separation of Microstructural and Microchemical Effects in Irradiation Assisted Stress Corrosion Cracking using Post-irradiation Annealing

Cited by 51 publications

References 14 publications

Deformation Structure in Highly Irradiated Stainless Steels

Deformation Structure in Highly Irradiated Stainless Steels

Current understanding of radiation-induced degradation in light water reactor structural materials

Angular Distribution of Slip Steps by Three-Dimensional Polycrystalline Model for Stainless Steel

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