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Materials and Fabrication

Natural Crack Growth Analyses for Circumferential and Axial PWSCC Defects in Dissimilar Metal Welds

[+] Author and Article Information
Do-Jun Shim1

 Engineering Mechanics Corporation of Columbus, 3518 Riverside Drive, Suite 202, Columbus, OH 43221djshim@emc-sq.com

Sureshkumar Kalyanam, Frederick Brust, Gery Wilkowski

 Engineering Mechanics Corporation of Columbus, 3518 Riverside Drive, Suite 202, Columbus, OH 43221

Mike Smith, Andrew Goodfellow

EdF Energy, Barnwood, Gloucester, GL4 3RS, UK

1

Corresponding author.

J. Pressure Vessel Technol 134(5), 051402 (Sep 06, 2012) (10 pages) doi:10.1115/1.4007040 History: Received November 07, 2011; Revised May 10, 2012; Published September 06, 2012; Online September 06, 2012

The natural crack growth analysis (sometimes referred to as advanced finite element analysis (AFEA)) methodology has been developed by the US NRC and the nuclear industry to evaluate the natural crack growth due to primary water stress corrosion cracking (PWSCC) in nickel-based alloy materials. The natural crack growth (or AFEA) methodology allows the progression of a planar crack subjected to typical stress corrosion cracking (SCC)-type growth laws by calculating stress intensity factors at every nodal point along the crack front and incrementally advancing the crack front in a more natural manner. This paper describes the step-by-step procedure enhancements that have been made to the existing AFEA methodology. A significant enhancement was the feature to evaluate axial crack growth, where the crack was contained within the susceptible material. This methodology was validated by performing an AFEA evaluation for the axial crack that was found in the V.C. Summer hot-leg dissimilar metal weld (DMW). Other enhancements to the AFEA methodology include: feature to handle nonidealized circumferential through-wall cracks, mapping of weld residual stress for crack growth, and determination of limiting crack size using elastic-plastic J-integral analysis that included secondary stress (weld residual stress and thermal transient stress) effects.

Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 18

Elastic-plastic J analysis results for initial and final axial through-wall cracks within the DMW

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Figure 19

Hoop WRS and axial crack growth results for V. C. Summer plant

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Figure 20

Hoop WRS and axial crack growth results for a K-shaped DMW

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Figure 21

Comparison of hoop WRS along weld center line of surge nozzle using various hardening laws

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Figure 22

Axial crack growth results for surge nozzle using mixed (combined) hardening law based WRS

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Figure 1

Crack length input for two different leak-rate calculation methods

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Figure 2

Surge nozzle geometry and finite element mesh used for weld residual stress analysis

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Figure 3

Axial WRS used for circumferential crack growth in surge nozzle

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Figure 4

Total axial stress (at center of crack) used for circumferential crack growth in surge nozzle (compared with other axial stress profiles)

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Figure 5

Typical circumferential crack FE mesh used for the present study

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Figure 6

Circumferential crack growth results for surge nozzle where time is normalized by time to leakage

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Figure 7

Illustration showing the sections of the model that were removed to obtain the cylinder model

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Figure 8

Example of elastic-plastic axial stress along the weld center line at various stages

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Figure 9

Comparison of elastic-plastic axial stress from the WRS model and that mapped to the fracture model

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Figure 10

Example of fracture model used for elastic-plastic J analysis

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Figure 11

Elastic-plastic J analysis results for (a) relatively deep surface crack, (b) initial TWC, and (c) limiting TWC (where limiting J value, Jinit  = 446.7 N/mm)

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Figure 12

ID and OD COD values obtained from elastic FE analysis

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Figure 13

Time from incipient leak to limiting through-wall crack

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Figure 14

Hoop WRS (isotropic hardening law) at selected paths

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Figure 15

Typical axial crack FE mesh used in the present study

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Figure 16

Comparison of hoop stress from the original WRS model and hoop stress mapped to the fracture model

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Figure 17

Axial crack growth results for surge nozzle using isotropic hardening law based WRS

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