scholarly journals Main mechanical factors affecting creep strain at crack tip of stress corrosion cracking in full life cycle

2018 ◽  
Vol 13 ◽  
pp. 1291-1296
Author(s):  
Yinghao Cui ◽  
He Xue ◽  
Shuai Wang ◽  
Xiaoyan Gong ◽  
Jianlong Zhang
Keyword(s):  
Life Cycle ◽  
Stress Corrosion ◽  
Creep Strain ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Factors Affecting ◽  
Full Life Cycle ◽  
Mechanical Factors ◽  
Full Life

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.

Study on Transition of Stress Corrosion Cracking to Sharp Edge Corrosion for a Liquids Pipeline

2018 ◽  
Author(s):  
Jiajun (Jeff) Liang ◽  
Ziqiang (Alex) Dong ◽  
Mengshan Yu ◽  
Mariko Dela Rosa ◽  
Gurwinder Nagra
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Synergistic Effects ◽  
Management Strategies ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Lessons Learned ◽  
Sharp Edge ◽  
Maximum Pressure ◽  
Arrest Growth

Although stress corrosion cracking (SCC) growth is attributed to the synergistic effects of stress and corrosion, these two factors can just as easily become competing mechanisms, with stress cycles driving growth (hydrogen, the by-product of corrosion, may facilitate the growth), and corrosion working to blunt the crack tip and arrest growth. It follows that reducing the maximum pressure and cycling severity can slow down the crack growth or even stop it, and aggressive corrosion can further blunt the sharp crack tip. The Authors have observed, on a particular Polyethylene (PE) tape coated pipeline, instances where SCC has exhibited a propensity to corrode and convert into sharp edge corrosion. This is attributed to the combined effects of limited corrosion protection and low stresses. The focus of the paper is to assist operators in recognizing this phenomenon and integrate lessons learned into pipeline integrity management strategies.

Quantifying the Crack Tip Oxidation Kinetics Parameters and Their Contribution to Stress Corrosion Cracking in High Temperature Water

2010 ◽  
Author(s):  
Tetsuo Shoji ◽  
Zhanpeng Lu ◽  
He Xue ◽  
Yubing Qiu ◽  
Kazuhiko Sakaguchi
Keyword(s):  
High Temperature ◽  
Water Chemistry ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Oxidation Kinetics ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
High Temperature Water ◽  
Austenitic Alloys ◽  
Temperature Water

Stress corrosion cracking is the result of the interaction between crack tip oxidation kinetics and crack tip mechanics. Oxidation kinetic processes for austenitic alloys in high temperate water environments are analyzed, emphasizing the effects of alloy composition and microstructure, temperature, water chemistry, etc. The crack chemistry is investigated with introducing the effect of aging on reactivity of crack sides and the throwing power of bulk water chemistry. Oxidation rate constants under various conditions are calculated based on quasi-solid state oxidation mechanism, which are incorporated in the theoretical growth rate equation to quantify the effects of several key parameters on stress corrosion cracking growth rates of austenitic alloys in high temperature water environments, especially the effect of environmental parameters on stress corrosion cracking of Ni-base alloys in simulated PWR environments and stainless steels in simulated boiling water environments.

Film Effects On Ductile/Brititle Behavior In Stress-Corrosion Cracking

1995 ◽  
Vol 409 ◽  
Author(s):  
Tong-Yi Zhang ◽  
Wu-Yang Chu ◽  
Ji-Mei Xiao
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Critical Stress ◽  
Fracture Behavior ◽  
Applied Load ◽  
Crack Tip ◽  
Critical Stress Intensity Factor ◽  
Corrosion Cracking ◽  
Dislocation Emission ◽  
Mode Iii

AbstractThe present work analyzes the effects of a passive film formed during stress corrosion cracking on ductile/brittle fracture behavior, considering the interaction of a screw dislocation with a thin film-covered mode III crack under an applied remote load. Exact solutions are derived, and the results show that the crack stress field due to the applied load is enhanced by a harder film or abated by a softer film. The critical stress intensity factor for dislocation emission from the crack tip is greatly influenced by both the stiffness and thickness of the filn. A dislocation is more easily to be emitted from the crack tip if the covered film has a shear modulus larger than that of the substrate. The opposite is also true, i.e., a softer film makes dislocation emission more difficult. Both phenomena become more significant when the film thickness is smaller.

Effect of Creep on Stress and Strain at the Tip of Stress Corrosion Cracking in High Temperature Water Environments

2014 ◽  
Vol 494-495 ◽  
pp. 651-654
Author(s):  
He Xue ◽  
Jin Tian ◽  
Fu Qiang Yang
Keyword(s):  
High Temperature ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Stress And Strain ◽  
Mechanical Parameters ◽  
High Temperature Water ◽  
High Pressure Environment ◽  
Temperature Water

Stress and strain at the crack tip are main mechanical parameters which estimate the stress corrosion cracking rate in metals, and the creep of metals in high temperature and high pressure environment will lead to the redistribution of stress and strain nearby the crack tip. The effects of creep on stress and strain nearby the crack tip are discussed by using 1T-CT specimen and finite element method in this study. The investigated results indicate that both increasing of temperature and stress intensity factor would induce the equivalent creep strain increases at the crack tip.

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