Modeling of Notch Effects on Stress Corrosion Cracking

1992 ◽  
Vol 114 (2) ◽  
pp. 171-177
Author(s):  
P. S. Maiya ◽  
B. K. Pai
Keyword(s):  
Strain Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Growth Rates ◽  
Corrosion Cracking ◽  
Elastic Plastic ◽  
Notched Specimens ◽  
Nominal Strain ◽  
Type 304

The intergranular stress corrosion cracking (IGSCC) of sensitized Type 304 stainless steel (SS) has been investigated by slow strain rate tests (SSRTs) in 289°C water containing sulfate impurity. Both smooth and circumferentially notched specimens were used to assess the effects of strain concentrations on stress corrosion cracking (SCC). Experiments were conducted over a range of nominal strain rates of 10−5 to 10−7 s−1. A comparison of the results observed for the smooth and notched specimens suggests that the estimated growth rates of small cracks in SSRT specimen geometry is influenced by the presence of strain concentrations. In particular, the average crack growth rates estimated from tests performed at the same nominal strain rate are observed to increase with the notch depth, and power-law relationships exist between strain rate and SCC parameters such as failure time and crack growth rate. The strain concentration factors at the notch roots of Type 304 specimens subjected to axial load have been estimated by finite-element elastic-plastic stress analyses, as well as by Neuber’s rule. The nominal and crack-tip strain rate effects on SCC in both smooth and notched specimens are interpreted in terms of a model based on elastic-plastic fracture mechanics and film-rupture mechanisms that invoke diffusion-controlled SCC growth kinetics.

Stress Corrosion Cracking of Inconel Alloys and Weldments in High-Temperature Water — the Effect of Sulfuric Acid Addition

CORROSION ◽  
1988 ◽  
Vol 44 (4) ◽  
pp. 239-247 ◽  
Author(s):  
A. McMinn ◽  
R. A. Page
Keyword(s):  
Sulfuric Acid ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Pure Water ◽  
Water Environment ◽  
Constant Load ◽  
Corrosion Cracking ◽  
Weld Metals

Abstract The stress corrosion cracking (SCC) susceptibilities of Alloys 600 and 690, AISI 316 NG stainless steel (SS), ASTM A508 carbon steel, and a number of compatible weld metals have been evaluated at 288 C in pure water and in pure water containing sulfuric acid additions. The sulfuric acid was added to simulate the effects of a resin release from the demineralizer system of a boiling water reactor (BWR). A combination of creviced and noncreviced slow strain rate, constant load, and crack growth rate tests were used in the evaluation. The results indicated that all of the alloys tested in the uncreviced condition were immune to cracking in the pure water environment. The presence of crevices in the pure water environment produced a susceptibility to SCC in Alloy 600, in Inconel I-82 and I-182 weld metals, and ASTM A508 steel, but not in Alloy 690. Cracking was enhanced by the addition of 1 ppm H2SO4 in slow strain rate tests (SSRTs) and constant load tests, but crack growth rates were not enhanced. All of the alloys tested in the resin intrusion environment were susceptible to cracking, except for the high chromium weld metals R-135 and Inconel I-72.

Effects of Cyclic Tensile Loading on Stress Corrosion Cracking Susceptibility for Sensitized Type 304 Stainless Steel in 290 C High Purity Water

CORROSION ◽  
1979 ◽  
Vol 35 (11) ◽  
pp. 523-531 ◽  
Author(s):  
HIROSHI TAKAKU ◽  
MORIYASU TOKIWAI ◽  
HIDEO HIRANO
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
High Purity ◽  
Corrosion Cracking ◽  
304 Stainless Steel ◽  
Intergranular Stress Corrosion ◽  
Type 304 ◽  
Type 304 Stainless Steel

Abstract The effects of load waveform on intergranular stress corrosion cracking (IGSCC) susceptibility have been examined for sensitized Type 304 stainless steels in a 290 C high purity water loop. Concerning the strain rate in the trapezoidal stress waveform, it was found that IGSCC susceptibility was higher for smaller values of the strain rate. It was also shown that IGSCC susceptibility became higher when the holding time at the upper stress was prolonged, and when the upper stress was high. The occurrence of IGSCC for sensitized Type 304 stainless steel became easy due to the application of cyclic tensile stress in 290 C high purity water.

SCC Behavior of Alloy 690 HAZ in a PWR Environment

2011 ◽  
Author(s):  
Bogdan Alexandreanu ◽  
Yiren Chen ◽  
Ken Natesan ◽  
Bill Shack
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Heat Affected Zone ◽  
Growth Rates ◽  
Water Environment ◽  
Corrosion Cracking ◽  
Alloy 690 ◽  
Crack Growth Rates

The objective of this work is to determine the cyclic and stress corrosion cracking (SCC) crack growth rates (CGRs) in a simulated PWR water environment for Alloy 690 heat affected zone (HAZ). In order to meet the objective, an Alloy 152 J-weld was produced on a piece of Alloy 690 tubing, and the test specimens were aligned with the HAZ. The environmental enhancement of cyclic CGRs for Alloy 690 HAZ was comparable to that measured for the same alloy in the as-received condition. The two Alloy 690 HAZ samples tested exhibited maximum SCC CGR rates of 10−11 m/s in the simulated PWR environment at 320°C, however, on average, these rates are similar or only slightly higher than those for the as-received alloy.

Stress Corrosion Cracking: Chemically Activated Nanomechanics

2016 ◽  
Author(s):  
Bruce C. Bunker ◽  
William H. Casey
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Growth Rates ◽  
Communication Systems ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Design Engineers ◽  
Mechanical Deformations ◽  
Crack Growth Rates

Although dissolution reactions involving water can etch and decompose oxides, truly catastrophic failures of oxide structures usually involve fractures and mechanical failures. Geologists and geochemists have long recognized that water and ice both play key roles in promoting the fracture and crumbling of rock (see Chapter 17). Freezing and thawing create stresses that amplify the rate at which water attacks metal–oxygen bonds at the crack tip. The interplay between water and stressed oxides also leads to common failures in man-made objects, ranging from the growth of cracks from flaws in windshields to the rupture of optical fibers in communication systems. In this chapter, we outline how mechanical deformations change the reactivity of metal–oxygen bonds with respect to water and other chemicals, and how reactions on strained model compounds have been used to predict time to failure as a function of applied stress. The basic phenomenon of stress corrosion cracking is illustrated in Figure 16.1. Cracks can propagate through oxide materials at extremely fast rates, as anyone who has dropped a wine glass on the floor can attest. High-speed photography reveals that when glass shatters, cracks can spread at speeds of hundreds of meters per second, or half the speed of sound in the glass. At the other end of the spectrum, cracks in glass can grow from preexisting flaws so slowly that only a few chemical bonds are broken at the crack tip per hour. Because mechanical failures are associated with cracking, it is critical for design engineers to understand the factors that control crack growth rates for this enormous range of crack velocities (a factor of 1012). In addition, because it is difficult to measure crack velocities slower than 10−8 m/second, it is often necessary to make major extrapolations from measured data to predict the long-term reliability of glass and ceramic objects. Will an optical fiber under stress fail in 1 year or 10 years? Answering this question can require accurate extrapolations down to crack growth rates as low as 10−10 m/second.

Modeling the Interactions of Hydrogen, Stress and Dissolution in Near-Neutral pH Stress Corrosion Cracking of Pipelines

2006 ◽  
Author(s):  
Frank Y. Cheng
Keyword(s):  
Stress Corrosion ◽  
Dissolution Rate ◽  
Crack Growth ◽  
Anodic Dissolution ◽  
Hydrogen Concentration ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Neutral Ph ◽  
Ph Stress

A thermodynamic model was developed to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip during near-neutral pH stress corrosion cracking in pipelines. By analyzing the free-energy of the steel in the presence and absence of hydrogen and stress, it is demonstrated that a synergism of hydrogen and stress promotes the cracking of the steel. The enhanced hydrogen concentration in the stressed steel significantly accelerates the crack growth. The quantitative prediction of the crack growth rate in near-neutral pH environment is based on the determination of the effect of hydrogen on the anodic dissolution rate in the absence of stress, the effect of stress on the anodic dissolution rate in the absence of hydrogen, the synergistic effect of hydrogen and stress on the anodic dissolution rate at the crack-tip and the effect of the variation of hydrogen concentration on the anodic dissolution rate.

Intergranular Stress Corrosion Cracking Damage Model: An Approach and Its Development for Alloy 600 in High-Purity Water

CORROSION ◽  
1986 ◽  
Vol 42 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Y. S. Garud ◽  
A. R. McIlree
Keyword(s):  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
High Purity ◽  
Corrosion Cracking ◽  
Model Parameters ◽  
Alloy 600 ◽  
Intergranular Stress Corrosion ◽  
Film Rupture ◽  
Intergranular Stress Corrosion Cracking

Abstract A logical approach to quantitative modeling of intergranular stress corrosion cracking (IGSCC) is presented. The approach is based on the supposition (supported partly by experimental and field observations, and by a related plausible underlying mechanism) that strain rate is a key variable. The approach is illustrated for the specific case of NiCrFe Alloy 600 in high-purity water. Model parameters are determined based on the constant stress IGSCC data (between 290 and 365 C) assuming a power law relation between the damage and the nominal strain rate. The model may be interpreted in terms of a film rupture mechanism of the corrosion process. The related mechanistic considerations are examined for the specific case. Resulting calculations and stress as well as temperature dependence are shown to be in good agreement with the data. More data are needed for further verification under specific conditions of interest.

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