Biaxial loading and shallow-flaw effects on crack-tip constraint and fracture toughness
- Oak Ridge National Lab., TN (United States)
A program to develop and evaluate fracture methodologies for the assessment of crack-tip constraint effects on fracture toughness of reactor pressure vessel (RPV) steels has been initiated in the Heavy-Section Steel Technology (HSST) Program. Crack-tip constraint is an issue that significantly impacts fracture mechanics technologies employed in safety assessment procedures for commercially licensed nuclear RPVs. The focus of studies described herein is on the evaluation of two stressed-based methodologies for quantifying crack-tip constraint (i.e., J-Q theory and a micromechanical scaling model based on critical stressed volumes) through applications to experimental and fractographic data. Data were utilized from single-edge notch bend (SENB) specimens and HSST-developed cruciform beam specimens that were tested in HSST shallow-crack and biaxial testing programs. Results from applications indicate that both the J-Q methodology and the micromechanical scaling model can be used successfully to interpret experimental data from the shallow- and deep-crack SENB specimen tests. When applied to the uniaxially and biaxially loaded cruciform specimens, the two methodologies showed some promising features, but also raised several questions concerning the interpretation of constraint conditions in the specimen based on near-tip stress fields. Fractographic data taken from the fracture surfaces of the SENB and cruciform specimens are used to assess the relevance of stress-based fracture characterizations to conditions at cleavage initiation sites. Unresolved issues identified from these analyses require resolution as part of a validation process for biaxial loading applications. This report is designated as HSST Report No. 142.
- Research Organization:
- Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering; Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- Nuclear Regulatory Commission, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 143960
- Report Number(s):
- NUREG/CR--6132; ORNL/TM--12498; ON: TI94007598
- Country of Publication:
- United States
- Language:
- English
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