Role of Mexican Clay Soils on Corrosiveness and Stress Corrosion Cracking of Low-Carbon Pipeline Steels: A Case Study

CORROSION ◽  
10.5006/3515 ◽  
2020 ◽  
Vol 76 (10) ◽  
pp. 967-984
Author(s):  
A. Contreras ◽  
L.M. Quej ◽  
H.B. Liu ◽  
J.L. Alamilla ◽  
E. Sosa
Keyword(s):  
Corrosion Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
The State ◽  
Clay Soils ◽  
Corrosion Mechanism ◽  
General Corrosion ◽  
Southern Mexico ◽  
Gauge Section

This work analyzed the physicochemical effect of different types of Mexican clay soils on corrosion and stress corrosion cracking (SCC) behavior in contact with X60 and X65 steels. Four soils were obtained from the right of way land in southern Mexico at 1.5 m depth close to pipelines. Two soils were from the state of Oaxaca (SO1 and SO2), and two others from the state of Veracruz (SV1 and SV2). Physicochemical and textural analysis of soils was performed and correlated to SCC susceptibility and corrosion mechanism. It was observed that soil texture might be related to corrosivity. A texture index (ratio between sand and silt + clay), which was seen to have a relationship with the corrosive tendency of soils, was estimated. It showed that soil with a higher index (SV1) has a higher corrosion rate. Electrochemical impedance spectroscopy and polarization curves were performed and correlated to the corrosion rate and the SCC susceptibility of steels. Steels exposed to SV1 soil exhibited a higher corrosion rate related to a higher content of chlorides and acid pH than those seen in other soils, which resulted in the pitting of such steels. Two types of corrosion were observed. Soils from SV1 and SV2 generated pitting, and soils from SO1 and SO2 produced general corrosion. Inclusions caused pitting in the gauge section of X60 and X65 steels exposed to SV1 soil by anodic dissolution. Galvanic coupling between inclusions and the base metal and dissolution of the inclusions might have enhanced the nucleation of pits at these sites. SCC susceptibility was evaluated using slow strain rate tests (SSRT). After SSRT, the fracture surfaces were analyzed through scanning electron microscopy. The SCC index obtained from SSRT indicates that X60 and X65 steels exhibited good resistance to SCC. A highly corrosive soil, such as SV1, causes the formation of pits instead of cracks, which is attributed to the dissolution process; however, lower SCC indexes were obtained for this system. The higher corrosion resistance of X60 steel is related to a more homogenous microstructure and a higher content of elements, such as Ni and Cr, than those of X65 steel that decrease the corrosion rate.

Film and pH Effects in the Stress Corrosion Cracking of Type 304 Stainless Steel

CORROSION ◽  
1970 ◽  
Vol 26 (10) ◽  
pp. 420-426 ◽  
Author(s):  
H. R. BAKER ◽  
M. C. BLOOM ◽  
R. N. BOLSTER ◽  
C. R. SINGLETERRY
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
304 Stainless Steel ◽  
Corrosion Mechanism ◽  
General Corrosion ◽  
Protective Film ◽  
Corrosion Resistant ◽  
Ph Range

Abstract Rapid stress corrosion cracking of 304 stainless steel in MgCl2-FeCl3 solutions at 125 C has been shown to occur only when the pH of the corrodent liquid within the crack lay between 1.2 and 2.5. A film of more acidic corrodent solution is raised to pH = 1.2 by reaction with the metal within a few seconds after isolation in a pit, crack, or crevice. MgCl2 solutions of pH higher than 2 became more acidic when in contact with stainless steel as a result of corrosion processes. The pH of small amounts of such solution isolated in pits or crevices eventually fell to near 1.5, where stress corrosion cracking could occur. This pH range is considered to be critical for stress corrosion cracking of 304 stainless steel because it is the range in which a corrosion resistant protective film is formed in the presence of the corrodent solution. This film is essential to crack propagation. If there is added to a corrodent , solution in this pH range an organic complexing agent such as glycerine or glycol which prevents-formation of the protective oxide film, the general corrosion process continues unchecked but no stress corrosion cracking occurs. The data support a model in which stress corrosion cracking is driven by a highly localized galvanic cell within the crack. The cell operates in such a way that there is no large change in pH of the solution in the crack. These results emphasize the importance of the corrosion resistant film in the chemical aspect of the stress corrosion mechanism.

scholarly journals Hydrogen-Induced Stress Corrosion Cracking of Pipe Lines of Russia

1996 ◽  
Author(s):  
Tatyana K. Sergeyeva ◽  
Igor A. Tychkin ◽  
Gennady G. Vasiliev
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Large Diameter ◽  
Corrosion Cracking ◽  
Slow Strain Rate Test ◽  
Corrosion Mechanism ◽  
Hydrogen Distribution ◽  
Induced Stress ◽  
Rate Test ◽  
Large Diameter Pipes

The results of expert studies of large diameter pipes damaged due to external stress corrosion cracking are presented in the report. These data obtained in the 1993–1995 are typical for various regions of Russia. The results of laboratory studies of the stress-corrosion mechanism for pipe steels in suspensions of soils from the places where the operating failure had occurred are given in the report also. The mechanism of hydrogen-induced stress-corrosion cracking (HISCC) realizing through local hydrogenation of steel during plastic deformation has been determined by means of the technique of slow strain rate test (SSRT) of samples in the soil under cathodic, anodic and free corrosion potentials in combination with hydrogenation and hydrogen distribution analyses along length of a sample. No hydrogenation of volumes of pipes non-subjected to cracking was observed but hydrogenation took place in the zones subjected to stress corrosion.

Surface Chemical Factors in the Stress-Corrosion Cracking off Alpha Brass

CORROSION ◽  
1966 ◽  
Vol 22 (6) ◽  
pp. 178-179 ◽  
Author(s):  
H. E. JOHNSON ◽  
J. LEJA
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Absolute Temperature ◽  
Corrosion Cracking ◽  
General Corrosion ◽  
Linear Relationships ◽  
Energy Lowering ◽  
Cracking Mechanisms ◽  
Ph Range ◽  
Alpha Brass

Abstract Stress corrosion cracking of alpha brass in ammonia solutions containing copper-ammonia complexes is most rapid in the pH range 6 to 7, where weight loss corrosion is insignificant, Linear relationships were found for (a) log 1/tc (tc = cracking time) vS log Cu++ (initial copper concentration) and (b) l/tc vs 1/T (T = absolute temperature). Oxygen appears necessary for general corrosion and cracking at pH values above 8. Rapid cracking is interpreted in terms of a drastic surface free energy decrease caused by the adsorption of an intermediate copper-zinc- ammonia complex (not yet identified) which is catalytically formed at the brass/solution interface and is surface active. It is suggested also that linear relationships like (a) and (b) above may be distinguishing features of stress corrosion cracking mechanisms which involve surface energy lowering.

Characterization of the Crack Propagation in the API X-52 and API X-65 Steels into Cathodic Protection

2009 ◽  
Vol 1242 ◽  
Author(s):  
A. Aguilar ◽  
R. Esparza ◽  
M.A. Gil ◽  
L.F. Cuahutitla ◽  
E. Rubio-Rosas ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Cathodic Protection ◽  
Reference Electrode ◽  
Important Variable ◽  
Corrosion Cracking ◽  
High Concentrations

ABSTRACTCathodic protection has been applied for many years as the best method to prevent the corrosion in systems which transported hydrocarbon pipelines. However, it has found the presence of stress corrosion cracking (SCC) in steel pipelines with high concentrations of carbonates and bicarbonates with pH final (9 to 11). The resistance to the stress corrosion cracking of the API X-52 and API X-65 steels was evaluated on compact modified wedge opening specimens (WOL). The specimens were loaded of 95% of the yield strength. The resistance of crack propagation and the corrosion rate were evaluated with different applied potentials (-850 and -650 mV), this with respect to a saturated copper/copper sulfate reference electrode. The used electrolytes were simulated soils (carbonate-bicarbonate solution). Evidence of crack propagation of the API X-52 and API X-65 steels were carried out by scanning electron microscopy. The obtained result showed susceptibility to SCC on specimens with cathodic protection. The cathodic protection applied (-850 mV vs Cu/CuSO4 electrode) decreases considerably the corrosion rate on the evaluated steels. In this work the loaded stress showed to be a very important variable on the susceptibility to SCC.

Corrosion and Stress Corrosion Cracking Susceptibility of Type 347H Stainless Steel in Supercritical Water

CORROSION ◽  
10.5006/2459 ◽  
2017 ◽  
Vol 74 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Xianglong Guo ◽  
Wenhua Gao ◽  
Kai Chen ◽  
Zhao Shen ◽  
Lefu Zhang
Keyword(s):  
Stainless Steel ◽  
Stress Corrosion ◽  
Oxygen Content ◽  
Supercritical Water ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
General Corrosion ◽  
Scattered Electron ◽  
Intergranular Cracking ◽  
Exposure Test

The corrosion resistance and stress corrosion cracking (SCC) susceptibility of Type 347H stainless steel (SS) in supercritical water (SCW) were investigated. The general corrosion behavior was investigated by exposure test and the specimens after testing were characterized utilizing scanning electron microscopy (SEM), Auger and x-ray diffraction analysis, optical microscopy, and energy dispersive spectroscopy (EDS). The results show that with the increase of testing temperature, the corrosion rate of the materials is greatly enhanced. The corrosion process is analyzed and the formation of oxide islands on the surface of the corroded sample is attributed to the higher diffusion rate of Cr along the grain boundary. The effects of temperature and dissolved oxygen on SCC susceptibility were investigated by slow strain rate tensile test. The fractographs were characterized by SEM and the cross-section morphologies were characterized with back-scattered electron imaging, SEM, and EDS. The results indicate that, as temperature is increased, the tensile strength and strain of materials is greatly reduced, while the oxygen content in SCW has a limited effect on the mechanical properties. Intergranular cracking and ductile fracture are the main fracture modes for Type 347H SS tested in SCW, independent of temperature and oxygen content. The implications of the results to the mechanisms of SCC are discussed.

Some Adverse Effects of Stress Corrosion in Steam Turbines

1977 ◽  
Vol 99 (2) ◽  
pp. 255-260
Author(s):  
R. E. Sperry ◽  
S. Toney ◽  
D. J. Shade
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Field Experiences ◽  
Corrosion Cracking ◽  
Material Behavior ◽  
Corrosion Mechanism ◽  
Steam Turbines ◽  
Critical Flaw ◽  
Size Growth

The performance and reliability of a steam turbine can be seriously impaired by the admission of steam of unacceptable quality. Of particular concern are contaminants such as caustic, chlorides, and sulfides which can promote the occurrence of corrosion attack and stress corrosion cracking. Critical flaw size growth from cracks initiated by the stress corrosion mechanism can result in brittle-type failure. The importance of stress corrosion as one of the failure mechanisms responsible for turbine outages indicates the need for some understanding of the essential aspects of this phenomenon. The metallurgical aspects of stress corrosion cracking, field experiences with turbine components in aggressive steam environments and results of a study of turbine-material behavior in caustic and sulfide environments are discussed. Field experiences discussed are limited to fossil-fueled industrial and small utility turbines. To further emphasize the serious consequences of stress corrosion failures, typical turbine outage times based on our experience are discussed.

Action of Carbon in Stress Corrosion Cracking of Mild Steel in Nitrate Solutions

CORROSION ◽  
1973 ◽  
Vol 29 (1) ◽  
pp. 37-46 ◽  
Author(s):  
J. FLIS
Keyword(s):  
Carbon Content ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Intergranular Corrosion ◽  
Corrosion Cracking ◽  
Total Carbon ◽  
General Corrosion ◽  
Low Carbon ◽  
Total Carbon Content ◽  
Protective Properties

Abstract The effect of total carbon content on susceptibility of iron to stress corrosion cracking (SCC), on the depth of intergranular corrosion without stresses, anodic polarization curves, and the general corrosion rate was examined on decarburized Armco iron and its ferritic or martensitic alloys with carbon up to 1.4% in 5N NH4NO3 and 5N Ca(NO3)2, pH 5.0, at 75 and 100 C (167 and 212 F). The susceptibility to SCC and intergranular corrosion increased with the carbon content increasing up to about 0.009% or above, and it diminished with further increase in the carbon content. Carbon decreased the ability of iron to passivate (depassivating action), but it also promoted deposition of magnetite and enhanced its protective properties (impeding action). It is suggested that the observed effect of carbon on SCC and intergranular corrosion results from the predominance of the depassivating action at low carbon contents, and the predominance of the impeding action at higher carbon contents.

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