Crack Initiation Mechanism in Non-ductile Cracking of Irradiated 304L Stainless Steels under BWR Water Environment

Takeo Onchi, Kenji Hohi, Marta Navas, Wade Karlsen

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)

Abstract

The deformation behavior and initiation mechanisms of intergranular (IG) and transgranular (TG) cracks in irradiated 304L stainless steel were studied by slow-strain-rate tensile tests in inert gas and simulated BWR water environments, followed by fractographic and microstructural examinations. Neutron irradiation was made in test reactors to fluences of up to 6.2x1020 n/cm2 (E>1 MeV). Intergranular cracking occurred in water above a critical neutron fluence of around 1 × 1020 n/cm2, based on the results of the SSRT tests and SEM fractography. That critical fluence is mechanistically supported by irradiated, deformed microstructures exhibiting dislocation channeling at that fluence, while radiation-induced Cr depletion at the grain boundaries was minor. Transgranular cracking of the irradiated material occurred in water below the critical fluence, initiating in the non-uniformly strained surface region of the test bar in the later stages of plastic deformation. The initiation of TG cracking is hypothesized to be related to a high density of deformation twins. Intergranular cracking is proposed to have initiated where localized slip bands terminated at grain boundaries, while TG cracking is inferred to have initiated at deformation twin boundaries. High stress and strain concentrations at grain/twin boundaries would be the common cause of non-ductile crack initiation.
Original languageEnglish
Pages (from-to)851-865
Number of pages5
JournalJournal of Nuclear Science and Technology
Volume43
Issue number8
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Fingerprint

crack initiation
Crack initiation
stainless steels
fluence
Grain boundaries
Stainless steel
water
Water
Fractography
Neutron irradiation
Inert gases
grain boundaries
Strain rate
Plastic deformation
fractography
Neutrons
stress concentration
Cracks
edge dislocations
neutron irradiation

Keywords

  • 304L stainless steel
  • neutron irradiation
  • intergranular cracking
  • transgranular cracking
  • plastic deformation localization
  • dislocation channeling
  • deformation twins
  • grain boundary
  • twin boundary
  • stress and strain concentration

Cite this

@article{43251b72b415464c919f3bfc37cf90a0,
title = "Crack Initiation Mechanism in Non-ductile Cracking of Irradiated 304L Stainless Steels under BWR Water Environment",
abstract = "The deformation behavior and initiation mechanisms of intergranular (IG) and transgranular (TG) cracks in irradiated 304L stainless steel were studied by slow-strain-rate tensile tests in inert gas and simulated BWR water environments, followed by fractographic and microstructural examinations. Neutron irradiation was made in test reactors to fluences of up to 6.2x1020 n/cm2 (E>1 MeV). Intergranular cracking occurred in water above a critical neutron fluence of around 1 × 1020 n/cm2, based on the results of the SSRT tests and SEM fractography. That critical fluence is mechanistically supported by irradiated, deformed microstructures exhibiting dislocation channeling at that fluence, while radiation-induced Cr depletion at the grain boundaries was minor. Transgranular cracking of the irradiated material occurred in water below the critical fluence, initiating in the non-uniformly strained surface region of the test bar in the later stages of plastic deformation. The initiation of TG cracking is hypothesized to be related to a high density of deformation twins. Intergranular cracking is proposed to have initiated where localized slip bands terminated at grain boundaries, while TG cracking is inferred to have initiated at deformation twin boundaries. High stress and strain concentrations at grain/twin boundaries would be the common cause of non-ductile crack initiation.",
keywords = "304L stainless steel, neutron irradiation, intergranular cracking, transgranular cracking, plastic deformation localization, dislocation channeling, deformation twins, grain boundary, twin boundary, stress and strain concentration",
author = "Takeo Onchi and Kenji Hohi and Marta Navas and Wade Karlsen",
year = "2006",
doi = "10.1080/18811248.2006.9711170",
language = "English",
volume = "43",
pages = "851--865",
journal = "Journal of Nuclear Science and Technology",
issn = "0022-3131",
publisher = "Atomic Energy Society of Japan",
number = "8",

}

Crack Initiation Mechanism in Non-ductile Cracking of Irradiated 304L Stainless Steels under BWR Water Environment. / Onchi, Takeo; Hohi, Kenji; Navas, Marta; Karlsen, Wade.

In: Journal of Nuclear Science and Technology, Vol. 43, No. 8, 2006, p. 851-865.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Crack Initiation Mechanism in Non-ductile Cracking of Irradiated 304L Stainless Steels under BWR Water Environment

AU - Onchi, Takeo

AU - Hohi, Kenji

AU - Navas, Marta

AU - Karlsen, Wade

PY - 2006

Y1 - 2006

N2 - The deformation behavior and initiation mechanisms of intergranular (IG) and transgranular (TG) cracks in irradiated 304L stainless steel were studied by slow-strain-rate tensile tests in inert gas and simulated BWR water environments, followed by fractographic and microstructural examinations. Neutron irradiation was made in test reactors to fluences of up to 6.2x1020 n/cm2 (E>1 MeV). Intergranular cracking occurred in water above a critical neutron fluence of around 1 × 1020 n/cm2, based on the results of the SSRT tests and SEM fractography. That critical fluence is mechanistically supported by irradiated, deformed microstructures exhibiting dislocation channeling at that fluence, while radiation-induced Cr depletion at the grain boundaries was minor. Transgranular cracking of the irradiated material occurred in water below the critical fluence, initiating in the non-uniformly strained surface region of the test bar in the later stages of plastic deformation. The initiation of TG cracking is hypothesized to be related to a high density of deformation twins. Intergranular cracking is proposed to have initiated where localized slip bands terminated at grain boundaries, while TG cracking is inferred to have initiated at deformation twin boundaries. High stress and strain concentrations at grain/twin boundaries would be the common cause of non-ductile crack initiation.

AB - The deformation behavior and initiation mechanisms of intergranular (IG) and transgranular (TG) cracks in irradiated 304L stainless steel were studied by slow-strain-rate tensile tests in inert gas and simulated BWR water environments, followed by fractographic and microstructural examinations. Neutron irradiation was made in test reactors to fluences of up to 6.2x1020 n/cm2 (E>1 MeV). Intergranular cracking occurred in water above a critical neutron fluence of around 1 × 1020 n/cm2, based on the results of the SSRT tests and SEM fractography. That critical fluence is mechanistically supported by irradiated, deformed microstructures exhibiting dislocation channeling at that fluence, while radiation-induced Cr depletion at the grain boundaries was minor. Transgranular cracking of the irradiated material occurred in water below the critical fluence, initiating in the non-uniformly strained surface region of the test bar in the later stages of plastic deformation. The initiation of TG cracking is hypothesized to be related to a high density of deformation twins. Intergranular cracking is proposed to have initiated where localized slip bands terminated at grain boundaries, while TG cracking is inferred to have initiated at deformation twin boundaries. High stress and strain concentrations at grain/twin boundaries would be the common cause of non-ductile crack initiation.

KW - 304L stainless steel

KW - neutron irradiation

KW - intergranular cracking

KW - transgranular cracking

KW - plastic deformation localization

KW - dislocation channeling

KW - deformation twins

KW - grain boundary

KW - twin boundary

KW - stress and strain concentration

U2 - 10.1080/18811248.2006.9711170

DO - 10.1080/18811248.2006.9711170

M3 - Article

VL - 43

SP - 851

EP - 865

JO - Journal of Nuclear Science and Technology

JF - Journal of Nuclear Science and Technology

SN - 0022-3131

IS - 8

ER -