Crack Tip Strain Distributions and Their Implications to Crack Growth Rate due to Stress Corrosion Cracking

2015 ◽  
Author(s):  
Shin-Jang Sung ◽  
Nikhil Kotasthane ◽  
Yugo Ashida ◽  
Jwo Pan
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Power Law ◽  
Stress Corrosion Cracking ◽  
Radial Distance ◽  
Crack Tip ◽  
Computational Results ◽  
Plastic Materials

In this paper, stress and strain distributions near a crack tip in a round compact tension specimen of elastic-plastic materials are obtained by finite element analyses. The strain distributions are used to explore the use of the crack tip strain distributions for crack growth rate models due to stress corrosion cracking in unirradiated and irradiated steels with different yield stresses and hardening behaviors. Both power-law hardening and perfectly plastic materials are considered. The computational results indicate that the critical radial distance to the tip based on the crack tip opening displacement is outside of the Hutchinson-Rice-Rosengren (HRR) dominant zone for power-law hardening materials in a round compact tension specimen under the stress intensity factor typically considered for stress corrosion cracking. For both the power-law hardening and perfectly plastic materials, the computational results show that the strain distributions are different from those of the analytical solutions for the range of the radial distance larger than the critical radial distance based on the crack opening displacement within the plastic zones. The computational results suggest that for the stress intensity factor typically considered for stress corrosion crack growth rate models, computational results are needed to estimate the strain rate for developing crack growth rate models to correlate to the experimental data.

scholarly journals The Application of Reliability-Based Design Factors in Stress Corrosion Cracking Evaluations

2002 ◽  
Author(s):  
Edward Friedman
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Initiation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Initiation Time ◽  
Reliability Based Design ◽  
Design Factors

First-order reliability methodology (FORM) is used to develop reliability-based design factors for deterministic analyses of stress corrosion cracking. The basic elements of FORM as applied to structural reliability problems are reviewed and then employed specifically to stress corrosion cracking evaluations. Failure due to stress corrosion cracking is defined as crack initiation followed by crack growth to a critical depth. The stress corrosion cracking process is thus represented in terms of a crack initiation time model and a crack growth rate model, with the crack growth rate integrated from the initiation time to the time at which the crack grows to its critical depth. Both models are described by log-normal statistical distribution functions. A procedure is developed to evaluate design factors that are applied to the mean values of the crack initiation time and the crack growth rate for specified temperature and stress conditions. The design factors, which depend on the standard deviations of the statistical distributions, are related to a target reliability, which is inversely related to an acceptable probability of failure. The design factors are not fixed, but are evaluated on a case-to-case basis for each application. The use of these design factors in a deterministic analysis assures that the target reliability will be attained and the corresponding acceptable probability of failure will not be exceeded. An example problem illustrates use of this procedure.

Crack Growth Rate Testing and Large Plate Demonstration Under Chloride-Induced Stress Corrosion Cracking Conditions in Stainless Steel Canisters for Storage of Spent Nuclear Fuel

2019 ◽  
Author(s):  
Poh-Sang Lam ◽  
Andrew J. Duncan ◽  
Lisa N. Ward ◽  
Robert L. Sindelar ◽  
Yun-Jae Kim ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Crack Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Nuclear Fuel ◽  
Stress Corrosion Cracking ◽  
Spent Nuclear Fuel ◽  
Compact Tension ◽  
Corrosion Cracking

Abstract Stress corrosion cracking may occur when chloride-bearing salts deposit and deliquesce on the external surface of stainless steel spent nuclear fuel storage canisters at weld regions with high residual stresses. Although it has not yet been observed, this phenomenon leads to a confinement concern for these canisters due to its potential for radioactive materials breaching through the containment system boundary provided by the canister wall during extended storage. The tests for crack growth rate have been conducted on bolt-load compact tension specimens in a setup designed to allow initially dried salt deposits to deliquesce and infuse to the crack front under conditions relevant to the canister storage environments (e.g., temperature and humidity). The test and characterization protocols are performed to provide bounding conditions in which cracking will occur. The results after 2- and 6-month exposure are examined in relation to previous studies in condensed brine and compared with other experimental data in the open literature. The knowledge gained from bolt-load compact tension testing is being applied to a large plate cut from a mockup commercial spent nuclear fuel canister to demonstrate the crack growth behavior induced from starter cracks machined in regions where the welding residual stress is expected. All these tests are conducted to support the technical basis for ASME Boiler and Pressure Vessel Section XI Code Case N-860.

Stress-Corrosion Cracking in Unidirectional GFRP Composites

2010 ◽  
Vol 430 ◽  
pp. 101-113
Author(s):  
Hideki Sekine ◽  
Peter W.R. Beaumont
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Intensity Factor ◽  
Glass Fiber ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Matrix Crack

A micromechanical theory of macroscopic stress-corrosion cracking in unidirectional glass fiber-reinforced polymer composites is proposed. It is based on the premise that under tensile loading, the time-dependent failure of the composites is controlled by the initiation and growth of a crack from a pre-existing inherent surface flaw in a glass fiber. A physical model is constructed and an equation is derived for the macroscopic crack growth rate as a function of the apparent crack tip stress intensity factor for mode I. Emphasis is placed on the significance of the size of inherent surface flaw and the existence of matrix crack bridging in the crack wake. There exists a threshold value of the stress intensity factor below which matrix cracking does not occur. For the limiting case, where the glass fiber is free of inherent surface flaws and matrix crack bridging is negligible, the relationship between the macroscopic crack growth rate and the apparent crack tip stress intensity factor is given by a simple power law to the power of two.

Atmospheric Stress Corrosion Cracking of Stainless Steel Rock Climbing Anchors, Part 2: Laboratory Experiments

CORROSION ◽  
10.5006/3242 ◽  
2019 ◽  
Vol 75 (11) ◽  
pp. 1371-1382 ◽  
Author(s):  
Tomáš Prošek ◽  
Jiří Lieberzeit ◽  
Alan Jarvis ◽  
Lionel Kiener
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Crack Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Rock Climbing ◽  
Corrosion Cracking ◽  
Critical Parameters ◽  
Electrolyte Ph

Atmospherically-induced stress corrosion cracking (AISCC) in the presence of chloride deposits has been responsible for considerable incidents of rock climbing anchors breaking under minimal loads in seaside locations, putting climbers lives at stake. However, to date, failures due to AISCC have only been documented in anchors made of Type 304/304L and similar, and no rigorously documented failures have been shown to occur to Type 316/316L anchors. In order to support preparation of a new standard classifying anchors according to their corrosion resistance, the influence of environmental parameters such as periodic washing of chloride deposits, electrolyte pH, and type of rock on AISCC initiation and crack growth rate was studied in laboratory conditions by exposing U-bent specimens of stainless steel Types 321, 304, and 316L with MgCl2 deposits in air at 40°C to 50°C and at 35% to 45% relative humidity. The type of rock and electrolyte pH were not critical parameters for AISCC. Alkaline conditions only slightly prolonged stable crack initiation period and decreased the crack growth rate. Periodic washing in sufficiently short intervals was capable of significantly retarding or even arresting AISCC. The crack growth rate in Type 316L stainless steel was 2- to 3-fold slower than in the molybdenum-free Types 304 and 321. These last two effects are quite likely responsible for the lack of failures observed in Type 316/316L. In view of the lifetime expectancy of rock climbing anchors and other safety-relevant members, the crack growth rate was unacceptably high in all studied materials and their installation should be avoided in vulnerable seaside regions.

Prediction of Materials Damage History From Stress Corrosion Cracking in Boiling Water Reactors

1999 ◽  
Vol 122 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Iouri Balachov ◽  
Digby Macdonald ◽  
Bernhard Stellwag ◽  
Norbert Henzel ◽  
Renate Kilian
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Boiling Water ◽  
Deterministic Models ◽  
Damage Functions ◽  
Operating Cycle

Over the past decade, we have developed deterministic models for predicting materials damage due to stress corrosion cracking (SCC) in boiling water reactor (BWR) primary coolant circuits. These steady-state models have been applied to fixed state points of reactor operation to yield electrochemical corrosion potential (ECP) and crack growth rate (CGR) predictions. However, damage is cumulative, so that prediction of the extent of damage at any given time must integrate crack growth rate over the history of the plant. In this paper, we describe the use of the REMAIN code to predict the accumulated damage functions for major components in the coolant circuit of a typical BWR that employs internal coolant pumps. As an example, the effect of relatively small amounts of hydrogen added to the feedwater (e.g., 0.5 ppm) on the development of damage from a 0.197-in. (0.5-cm) intergranular crack located at the exit of an internal pump was analyzed. It is predicted that hydrogen additions to the feedwater will effectively suppress further growth of the crack. We also report the first predictions of the accumulation of damage from SCC for a variable power operating cycle. We predict that the benefits of hydrogen water chemistry (HWC), as indicated by the behavior of a single crack under constant environmental conditions, are significantly muted by changes in reactor power. [S0094-9930(00)01301-9]

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