scholarly journals Fracture, Fatigue, and Structural Integrity of Metallic Materials

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 913
Author(s):  
Sergio Cicero ◽  
José Alberto Álvarez
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Structural Integrity ◽  
Creep Crack Growth ◽  
Corrosion Cracking ◽  
Metallic Materials ◽  
Creep Crack ◽  
Points Of View ◽  
Open Issues

Fracture, fatigue, and other subcritical processes, such as creep crack growth or stress corrosion cracking, present numerous open issues from both scientific and industrial points of view [...]

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.

Flaw Evaluation for PWR and BWR Component Weld Joints Using Advanced FEA Modeling Techniques

2009 ◽  
Author(s):  
T. Hayashi ◽  
S. F. Hankinson ◽  
T. Saito ◽  
C. K. Ng ◽  
W. H. Bamford
Keyword(s):  
Crack Propagation ◽  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Structural Integrity ◽  
Corrosion Cracking ◽  
Water Reactor ◽  
Crack Shape ◽  
Weld Joints ◽  
Flaw Shape

Primary Water Stress Corrosion Cracking (PWSCC) of Pressurized Water Reactor (PWR) primary loop piping/nozzle Dissimilar Metal Weld (DMW) joints and Inter Granular Stress Corrosion Cracking (IGSCC) of Boiling Water Reactor (BWR) weld joints is an ongoing issue in the nuclear power industry. Recent field experiences with PWSCC of various DMW joints in US plants led to the development and application of an Advanced Finite Element Analyses (AFEA) methodology that permits crack propagation with a natural flaw shape. Crack growth and fracture evaluations for both PWR and BWR components are generally performed based on a conservative, idealized crack shape model, e.g. semi-ellipse, rectangle, etc., depending on the geometry of the crack and the component. Conventional evaluation methodologies and/or assumptions of this kind, in some cases may provide excessive conservatisms. The use of natural flaw shape development with crack propagation might provide a more realistic assessment of crack growth and structural integrity. The prime purpose of this study is to demonstrate the conservatism/margins in the conventional “idealized crack shape” methodology. A comparison study of crack growth behavior between the applications of the idealized and natural crack shape methodologies has been performed in order to assess the level of conservatism/margins in the conventional crack growth evaluation methodology and the possible impacts on the structural integrity evaluation for both PWR and BWR components. Comparison studies on the impacts of the differences in crack growth law and loading condition used for crack growth evaluations have been performed as well.

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.

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.

Stress Corrosion Cracking of Structural Nuclear Materials: Influencing Factors and Materials Selection

2020 ◽  
Vol 10 (1) ◽  
pp. 5-24
Author(s):  
Renato Altobelli Antunes ◽  
Mara Cristina Lopes de Oliveira
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Alloy Composition ◽  
Scientific Literature ◽  
Corrosion Cracking ◽  
Nuclear Materials ◽  
Metallic Materials ◽  
Materials Selection ◽  
Complex Interactions ◽  
Successful Design

Stress Corrosion Cracking (SCC) plays a central role in the development of improved structural nuclear materials. Complex interactions between microstructure, alloy composition, manufacturing and environmental factors make the understanding of this phenomenon difficult. This work aimed at reviewing the scientific literature on the SCC behavior of structural nuclear materials in order to identify the main factors that govern this phenomenon. Additionally, the interaction between these factors and materials selection is discussed in order to provide a comprehensive basis for the successful design of metallic materials with improved resistance to SCC.

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