EIS analysis on stress corrosion initiation of pipeline steel under disbonded coating in near-neutral pH simulated soil electrolyte (original) (raw)

Corrosion Study of Pipeline Steel under Stress at Different Cathodic Potentials by EIS

Metals

The effect of different cathodic potentials applied to the X70 pipeline steel immersed in acidified and aerated synthetic soil solution under stress using a slow strain rate test (SSRT) and electrochemical impedance spectroscopy (EIS) was studied. According to SSRT results and the fracture surface analysis by scanning electron microscopy (SEM), the steel susceptibility to stress corrosion cracking (SCC) increased as the cathodic polarization increased (Ecp). This behavior is attributed to the anodic dissolution at the tip of the crack and the increment of the cathodic reaction (hydrogen evolution) producing hydrogen embrittlement. Nevertheless, when the Ecp was subjected to the maximum cathodic potential applied (−970 mV), the susceptibility decreased; this behavior is attributed to the fact that the anodic dissolution was suppressed and the process of the SCC was dominated only by hydrogen embrittlement (HE). The EIS results showed that the cathodic process was influenced by the ma...

Electrochemical Corrosion Behavior of API 5L X52 Pipeline Steel in Soil Environment

Analytical and Bioanalytical Electrochemistry, 2021

In this work, the corrosion rate of X52 pipeline steel used in Algerian soil was calculated and compared to that of a simulated soil solution (NS4). The effect of soil related parameters such as pH, temperature and immersion time on the corrosion of steel in NS4 solution is studied using different methods such as open circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy and energy dispersive spectrometry (EDX) coupled with scanning electron microscopy. The results are well correlated and showed that the corrosion rate increases when the medium is acidic or alkaline and when the temperature increases. The load transfer resistance increases with immersion time up to 3 days and then decreases with the presence of a film of corrosion products on the steel surface which becomes porous. It was also found that the corrosion rate of X52 steel immersed in the aqueous soil extract collected in southern Algeria is the lowest.

Stress corrosion cracking initiation under the disbonded coating of pipeline steel in near-neutral pH environment

Corrosion Science, 2010

A novel test setup has been used in this study to simulate stress corrosion cracking initiation under a disbonded coating on an X-65 pipeline steel. In this setup, the synergistic effects of cyclic loading, cathodic protection and soil solution environment under disbonded coatings have been considered. When the X-65 pipeline steel was exposed to the test environment, there existed a wide range of corrosion products on the steel surface in the gradient of cathodic protection. Increasing the test time and the maximum stress increased the possibility of stress corrosion cracking initiation in regions with a high susceptibility to pitting corrosion.