Study of SCC of X70 Steel Immersed in Simulated Soil Solution at Different pH by EIS

An electrochemical study of stress corrosion cracking (SCC) of API X70 steel in a simulated soil solution at different pH values (3, 8 and 10) was carried out. The stress conditions were implemented by slow strain rate stress test (SSRT) and the SCC process was simultaneously monitored by electroche...

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Bibliographic Details
Published in:Materials 2021-12, Vol.14 (23), p.7445
Main Authors: Carmona-Hernandez, Andres, Orozco-Cruz, Ricardo, Mejía-Sanchez, Edgar, Espinoza-Vazquez, Araceli, Contreras-Cuevas, Antonio, Galvan-Martinez, Ricardo
Format: Article
Language:English
Subjects:
Anodic dissolution
Charge transfer
Corrosion
Corrosion products
Corrosion tests
Crack initiation
Diffusion
Dissolution
Electrochemical impedance spectroscopy
Electrodes
Electrolytes
Fracture surfaces
High strength low alloy steels
Hydrogen embrittlement
Hydrogen evolution
Photomicrographs
Propagation
Scanning electron microscopy
Slow strain rate
Soils
Spectrum analysis
Steel
Stress corrosion cracking
Stress-strain curves
Surface analysis (chemical)
Uniform attack (corrosion)
Yield strength
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Summary:An electrochemical study of stress corrosion cracking (SCC) of API X70 steel in a simulated soil solution at different pH values (3, 8 and 10) was carried out. The stress conditions were implemented by slow strain rate stress test (SSRT) and the SCC process was simultaneously monitored by electrochemical impedance spectroscopy (EIS). Fracture surface analysis and corrosion product analysis were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results show that the susceptibility to SCC was higher as the pH decreases. In the acid solution, hydrogen evolution can occur by H+ and H2CO3 reduction, and more atomic hydrogen can diffuse into the steel, producing embrittlement. EIS results indicated that the anodic dissolution contributed to SCC process by reducing the charge transfer resistances during the SSRT test. While SEM micrographs shown a general corrosion morphology on the longitudinal surface of samples. At higher pH (pH 8 and pH 10), the SCC susceptibility was lower, which it is attributed to the presence of corrosion products film, which could have limited the process. Using the angle phase (φ) value it was determined that the cracking process started at a point close to the yield strength (YS).
ISSN:1996-1944
1996-1944
DOI:10.3390/ma14237445