Micro-Electrochemical Characterization of the Synergism of Hydrogen and Stress in Anodic Dissolution of Steel and Its Implication on Pipeline Stress Corrosion Cracking

2008 ◽  
Author(s):  
Y. Frank Cheng ◽  
X. Tang
Keyword(s):  
Stress Corrosion ◽  
Anodic Dissolution ◽  
Stress Corrosion Cracking ◽  
Electrochemical Impedance ◽  
Product Layer ◽  
Corrosion Cracking ◽  
Stress Effect ◽  
Effect Factor ◽  
Neutral Ph ◽  
Corrosion Product Layer

Localized electrochemical impedance spectroscopy (LEIS) technique was used to investigate the effects of stress and hydrogen as well as their synergism on anodic dissolution of steel under near-neutral pH condition where pipeline stress corrosion cracking (SCC) has been reported. There exists a threshold stress value, under which there is little effect of applied stress on anodic dissolution of steel. Above the value, the dissolution rate of steel increases with the stress. Hydrogen-charging enhances anodic dissolution of steel, which is attributed to the effect of hydrogen on the formation of corrosion product layer and the activation of the steel. The stress effect factor and the stress-hydrogen synergism effect factor are quantified. A detailed analysis shows that the synergism of stress and hydrogen at crack tip is expected to play an important role in near-neutral pH SCC of pipelines.

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.

scholarly journals Influence of the ultrasonic surface rolling process on stress corrosion cracking susceptibility of high strength pipeline steel in neutral pH environment

RSC Advances ◽  
2017 ◽  
Vol 7 (59) ◽  
pp. 36876-36885 ◽  
Author(s):  
Bingying Wang ◽  
Yu Yin ◽  
Zhiwei Gao ◽  
Zhenbo Hou ◽  
Wenchun Jiang
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pipeline Steel ◽  
High Strength ◽  
Rolling Process ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
Enhancement Technique ◽  
Neutral Ph ◽  
Developed Surface

A developed surface enhancement technique, USRP, was applied on X80 pipeline steel and the stress corrosion cracking susceptibility was studied.

Hydrogen Facilitated Anodic Dissolution Type Stress Corrosion Cracking of Pipeline Steels in Coating Disbondment Chemistry

1998 ◽  
Author(s):  
Scott X. Mao ◽  
J. L. Luo ◽  
B. Gu ◽  
W. Yu
Keyword(s):  
Stress Corrosion ◽  
Anodic Dissolution ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Strain Rates ◽  
Pipeline Steels ◽  
Dilute Aqueous Solution ◽  
Sims Analysis ◽  
Cracking Process ◽  
Secondary Ion

The stress corrosion cracking (SCC) of pipeline steels in coating disbondment chemistry (near neutral pH solution) was studied by using slow strain rate tests (SSRT), polarization techniques, SEM and SIMS (secondary ion mass spectroscope). It was found that SCC susceptibility increased as the applied electrochemical potential and strain rates decreased. Hydrogen (H) precharging or addition of CO2 facilitated the process of SCC, suggesting that dissolution and hydrogen ingress are involved in the cracking process. SIMS analysis showed that hydrogen could diffuse into steels around the crack tip during the SCC process, which would facilitate the dissolution rate of the steel and increase SCC susceptibility. A mechanism was proposed which shows that hydrogen enhances anodic dissolution type of SCC in dilute aqueous solution. A thermodynamic analysis of the SCC process was carried out, and was found to be consistent with the experimental results.

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