Effect of SO42− ion impurity on stress corrosion behavior of Ni-16Mo-7Cr alloy in FLiNaK salt

The aim of this study is to investigate the impact of immersion time, at different time values for two cases, with stressed and no stressed on materials. This study is conducted using SUS304 material with the presence of 3.5% NaCl at the range of stresses for the specimens lower than the yield strength. The geometry of the C-ring specimen was selected for 18.974 mm and 1.244 mm for the outer diameters and the thickness respectively. The immersion time effect was investigated using the half-cell potential measurement following the ASTM G-38 standard. The approach of corrosion environment was applied to resemble the condition of loading history. Three levels of stresses were designed and applied in finite element analysis and the results known as the parameters of stress-corrosion measurement. The ASTM G-38 standard is prominent for making C-ring stress-corrosion for elastic stress analysis. The stress-corrosion test was performed at two parameters, fixed stress and no stress. The value of stresses for fixed stress was chosen for 179.199 MPa, 328.665 MPa and 460.131 MPa, correspondingly. The immersion time were selected from 0, 10 and 30 days. The electrochemical result shows that the immersion time did not affect vastly to the corrosion behavior for no stress-corrosion compared with fixed stress. The corrosion rate increases proportionally with the time immersion increments due to the inability of the steel layer protection to regenerate itself. Subsequently, it is also due to the metal was exposed to plastic deformation that resulting the internal stresses due to the plastic anisotropy of the grains.

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A Three-Dimensional Coupled Finite Element Model for the Simulation of Stress Corrosion on Pipeline Steel

ASME 2019 Asia Pacific Pipeline Conference ◽

10.1115/appc2019-7603 ◽

2019 ◽

Author(s):

Dongxu Sun ◽

Ming Wu ◽

Fei Xie ◽

Ke Gong

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Stress Corrosion ◽

Corrosion Behavior ◽

Pipeline Steel ◽

Three Dimensional ◽

Element Model ◽

Circumferential Direction ◽

The Self ◽

Corrosion Defect

Abstract In this study, a three-dimensional finite element model was constructed to study the stress corrosion behavior of pipeline steel. Stress analysis and electrochemical calculation were incorporated into the model through multiphysics field coupling technique. Tensile property and electrochemical corrosion behavior of X70 pipeline steel were measured by experiments to formulate the model. The modeling results show that the corrosion is accelerated on the surface of corrosion defect where the stress tends to concentrate because of mechanoelectrochemical effect. The effect of elastic strain on corrosion enhancement is not obvious. The plastic deformation on defect bottom increases the corrosion rate significantly, especially for the conditions with high operating pressure or large defect depth. The corrosion current distribution indicated that the “self-acceleration effect” exists on corrosion defect. This effect makes the corrosion develop to depth and the shape of corrosion defects is more likely to cause stress concentration, and finally induces corrosion perforation or cracking. The two directions, i.e. axial and circumferential direction, have the different stress corrosion behaviors. The “self-acceleration effect” is more obvious on circumferential direction than that on axial direction, which can explain the phenomenon that there are mostly axial stress corrosion cracks on the pipeline in field.

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Effect of alternating current and Bacillus cereus on the stress corrosion behavior and mechanism of X80 steel in a Beijing soil solution

Bioelectrochemistry ◽

10.1016/j.bioelechem.2019.01.006 ◽

2019 ◽

Vol 127 ◽

pp. 49-58 ◽

Cited By ~ 8

Author(s):

Hongxia Wan ◽

Dongdong Song ◽

Cuiwei Du ◽

Zhiyong Liu ◽

Xiaogang Li

Keyword(s):

Bacillus Cereus ◽

Stress Corrosion ◽

Soil Solution ◽

Corrosion Behavior ◽

Alternating Current ◽

X80 Steel

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Effect of CO2/H2S and Applied Stress on Corrosion Behavior of 15Cr Tubing in Oil Field Environment

Metals ◽

10.3390/met10030409 ◽

2020 ◽

Vol 10 (3) ◽

pp. 409

Author(s):

Xuehui Zhao ◽

Wei Huang ◽

Guoping Li ◽

Yaorong Feng ◽

Jianxun Zhang

Keyword(s):

Stainless Steel ◽

Partial Pressure ◽

Stress Corrosion ◽

Applied Stress ◽

Corrosion Behavior ◽

Stress Corrosion Cracking ◽

Corrosion Cracking ◽

Oil Field ◽

Uniform Corrosion ◽

Field Environment

The corrosion behavior of a 15Cr-6Ni-2Mo martensitic stainless steel (15Cr stainless steel) in a CO2/H2S environment was investigated by conducting high-temperature/high-pressure immersion tests combined with scanning electron microscopy and metallographic microscopy. The presence of H2S decreased the corrosion resistance of the 15Cr tubing steel. The critical H2S partial pressure (PH2S) for stress corrosion cracking in the 15Cr tubing steel in the simulated oil field environment with a CO2 partial pressure of 4 MPa and an applied stress of 80% σs was identified. The 15Cr tubing steel mainly suffered uniform corrosion with no pitting and cracking when the PH2S was below 0.5 MPa. When the PH2S increased to 1 MPa and the test temperature was 150 °C, the pitting and cracking sensitivity increased. The stress corrosion cracking at a higher PH2S is attributed to the sulfide-induced brittle fracture.

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