Theoretical and Experimental Study of Stress Corrosion Cracking of Pipeline Steel in Near Neutral pH Environment

2000 ◽  
Author(s):  
B. Zhang ◽  
J. Fan ◽  
Y. Gogotsi ◽  
A. Chudnovsky ◽  
A. Teitsma
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Hydrogen Diffusion ◽  
Corrosion Cracking ◽  
Experimental Program ◽  
Multiple Cracks ◽  
Crack Interaction ◽  
Kinetic Coefficients ◽  
Crack Growth Model

Stress corrosion cracking (SCC) is a complex phenomenon that involves various interacting physical and chemical processes. There is a combination of determinism and stochasticity that results in SCC colony evolution. A statistical model that generates a random field of corrosion pits and crack initiation at randomly selected pits is proposed in this work. A thermodynamic model of individual SC crack growth has been recently developed within the framework of the Crack Layer theory. Mathematical realization of the SC crack growth model is presented in the form of relations between the crack growth, hydrogen diffusion and corrosion rates on one hand and corresponding thermodynamic forces on the other. Experimental program for determination of the kinetic coefficients employed in crack growth equations is briefly reported. Finally, application of the individual crack growth law to random configuration of multiple cracks results in a simulation of SCC colony evolution, including a stage of the large-scale crack interaction. The solution of the crack interaction problem via FRANC2D Finite Element Methods results in a computer simulation of multi-crack cluster formation within the colony.

Remaining Lifetime Assessment of Pipelines With Multiple Cracks Induced by Stress Corrosion Cracking

2002 ◽  
Author(s):  
Margarita G. Malyukova ◽  
Sviatoslav A. Timashev
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Multiple Cracks ◽  
J Integral ◽  
Remaining Life ◽  
Multiple Stress ◽  
Numerical Examples

In this paper an algorithm is proposed of assessing the remaining life using the J-integral crack growth criteria for a pipeline with multiple stress corrosion (SC) cracks accounting for their interaction. Numerical examples are given for one, two and five SC cracks.

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.

Weld Residual Stresses and Primary Water Stress Corrosion Cracking in Bimetal Nuclear Pipe Welds

2007 ◽  
Author(s):  
Frederick W. Brust ◽  
Paul M. Scott
Keyword(s):  
Water Stress ◽  
Residual Stresses ◽  
Weld Metal ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Pressure Vessel ◽  
Large Diameter ◽  
Corrosion Cracking ◽  
Primary Water

There have been incidents recently where cracking has been observed in the bi-metallic welds that join the hot leg to the reactor pressure vessel nozzle. The hot leg pipes are typically large diameter, thick wall pipes. Typically, an inconel weld metal is used to join the ferritic pressure vessel steel to the stainless steel pipe. The cracking, mainly confined to the inconel weld metal, is caused by corrosion mechanisms. Tensile weld residual stresses, in addition to service loads, contribute to PWSCC (Primary Water Stress Corrosion Cracking) crack growth. In addition to the large diameter hot leg pipe, cracking in other piping components of different sizes has been observed. For instance, surge lines and spray line cracking has been observed that has been attributed to this degradation mechanism. Here we present some models which are used to predict the PWSCC behavior in nuclear piping. This includes weld model solutions of bimetal pipe welds along with an example calculation of PWSCC crack growth in a hot leg. Risk based considerations are also discussed.

scholarly journals Interaction of Cyclic Loading (Low-Cyclic Fatigue) with Stress Corrosion Cracking (SCC) Growth Rate

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Rehmat Bashir ◽  
He Xue ◽  
Rui Guo ◽  
Yueqi Bi ◽  
Muhammad Usman
Keyword(s):  
Growth Rate ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Cyclic Fatigue ◽  
Joint Effect ◽  
Corrosion Cracking

The structural integrity analysis of nuclear power plants (NPPs) is an essential procedure since the age of NPPs is increasing constantly while the number of new NPPs is still limited. Low-cyclic fatigue (LCF) and stress corrosion cracking (SSC) are the two main causes of failure in light-water reactors (LWRs). In the last few decades, many types of research studies have been conducted on these two phenomena separately, but the joint effect of these two mechanisms on the same crack has not been discussed yet though these two loads exist simultaneously in the LWRs. SCC is mainly a combination of the loading, the corrosive medium, and the susceptibility of materials while the LCF depends upon the elements such as compression, moisture, contact, and weld. As it is an attempt to combine SCC and LCF, this research focuses on the joint effect of SCC and LCF loading on crack propagation. The simulations are carried out using extended finite element method (XFEM) separately, for the SCC and LCF, on an identical crack. In the case of SCC, da/dt(mm/sec) is converted into da/dNScc (mm/cycle), and results are combined at the end. It has been observed that the separately calculated results for SCC da/dNScc and LCF da/dNm of crack growth rate are different from those of joint/overall effect,  da/dNom. By applying different SCC loads, the overall crack growth is measured as SCC load becomes the main cause of failure in LWRs in some cases particularly in the presence of residual stresses.

Continuity of Environmentally Assisted Fatigue and Stress Corrosion Cracking Based on Short Crack Growth Behavior of 316 Stainless Steel in Simulated PWR Primary Water

2017 ◽  
Author(s):  
Choongmoo Shim ◽  
Yoichi Takeda ◽  
Tetsuo Shoji
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Water Environment ◽  
Growth Behavior ◽  
Corrosion Cracking ◽  
Short Crack ◽  
Crack Growth Behavior ◽  
Primary Water

Environmental correction factor (Fen) is one of the parameters to evaluate the effect of a pressurized high temperature water environment. It has been reported that Fen for stainless steel saturates at a very low strain rate. However, the relationship between environmentally assisted fatigue (EAF) and stress corrosion cracking (SCC) is still unclear. The aim of this study is to investigate the short crack growth behavior and possible continuity of EAF and SCC at very low strain rates. Short crack initiation and propagation have similar behaviors, which retard the crack growth between 100–200 μm in depth. We find that the striation spacing correlates well with the maximum crack growth rate (CGR) data. Based on the correlation, it is clarified that the local CGR on an intergranular facet was faster than that on a transgranular facet. Furthermore, the overall maximum and average CGR from the EAF data is well interpreted and compared with the SCC data.

Stress Corrosion Cracking of Depleted Uranium Alloys in Moist Salt Ladened Air

CORROSION ◽  
1981 ◽  
Vol 37 (2) ◽  
pp. 81-88 ◽  
Author(s):  
D. F. Hasson ◽  
J. A. Joyce ◽  
C. R. Crowe
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Depleted Uranium ◽  
Computer Data ◽  
Computer Data Acquisition ◽  
Heat Treated ◽  
Threshold Data ◽  
Mixed Fracture

Abstract Stress corrosion cracking (SCO in selected depleted uranium alloys in salt ladened moist air environments has been studied by cantilever beam testing. Crack growth kinetics were monitored during the test using a computer data acquisition system. Continuous measurements of crack growth with time showed discontinuous crack growth with increasing KI. Threshold stress intensity values for stress corrosion cracking KISCC, were found to be 24.4 MPa - m½ and 15.6 MPa - m½ for U-3/4 Ti and DU-3/4 Quintalloys, respectively. Values for U-2 Mo in two heat treated conditions were slightly less than the U-3/4 Ti threshold. Data is presented in a “safe zone” plot of flaw size vs applied stress. Fractographic investigation by scanning electron microscopy revealed mixed fracture modes with both transgranular and intergranular fracture occurring.

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