Pitting Behavior of 304 Stainless Steel in Simulated Condensate in Refining High Sulfur and Salt Heavy Oil

2015 ◽  
Vol 814 ◽  
pp. 249-255
Author(s):  
Xiao Hong Wang ◽  
Xiao Hua Guo ◽  
Yuan Hua Lin ◽  
Ying Ying Li ◽  
Shu Liang Wang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heavy Oil ◽  
Salt Content ◽  
Chloride Ions ◽  
304 Stainless Steel ◽  
Pitting Potential ◽  
Condensed Water ◽  
Sulfide Ions ◽  
Corrosion Pits ◽  
Static Immersion

The pitting behavior of 304 stainless steel in the simulated condensate with different salt content (4 mg/L, 8 mg/L, 16 mg/L, 32 mg/L, 64 mg/L) and sulfur content (1.2 g/L, 2.5 g/L, 5 g/L) was studied using potentiodynamic polarization curve and static immersion methods. The simulated condensate was simulating the condensed water in the unit of refining heavy oil with high salt and high sulfur. The results showed that with the increase in chloride ions concentration, the pitting potential of 304 stainless steel decreased and the pitting sensitivity increased. The pitting sensitivity of 304 stainless steel also increased with the increase in sulfide ions concentration. In several experimental mediums, when the concentration of chloride ions and sulfide ions were 64 mg/L, 5 g/L respectively, the number and the size of corrosion pits both were the largest, the pitting behavior was the most serious.

Effects of the α/γ-Phase Ratio on the Corrosion Behavior of Cast Duplex Stainless Steel

CORROSION ◽  
10.5006/3464 ◽  
2020 ◽  
Vol 76 (9) ◽  
pp. 815-825
Author(s):  
Ryotaro Yamamoto ◽  
Hiroshi Yakuwa ◽  
Matsuho Miyasaka ◽  
Nobuyoshi Hara
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Chloride Ions ◽  
Phase Ratio ◽  
Potential Range ◽  
High Concentration ◽  
Active Dissolution ◽  
Pitting Potential ◽  
Potential Measurement ◽  
Α Phase

The effects of the α/γ-phase ratio on pitting corrosion initiation and growth in cast duplex stainless steel were studied, including the preferential dissolution of the two phases inside the pits, using pitting potential measurement and potentiostatic polarization measurement with a high concentration of chloride ions and a low pH. The initiation of pitting was not dependent on the α-phase ratio. The γ phase preferentially dissolves when a high potential in the active dissolution region is applied, and the α phase preferentially dissolves when a low potential is applied. In addition, with an increase in α-phase ratio, the potential range where the α phase preferentially dissolves enlarged toward the higher potential side. The growth rate of stable pitting increased with the α-phase ratio. Dissolution of the α phase increased with an increase in the α-phase ratio. This phenomenon is presumably caused by the decreased amount of Cr in the α phase, resulting from the increased α-phase ratio, as well as by Cr depletion around Cr nitrides.

Research on the Failure Mechanism of Pitting Corrosion of the 304 Stainless Steel in Chloride Ions Environment

2012 ◽  
Vol 502 ◽  
pp. 12-16
Author(s):  
Yi Pan ◽  
Rong Fa Chen ◽  
Du Xiong Wang ◽  
Guo Sheng Cai ◽  
Xian Liang Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Rate ◽  
Failure Mechanism ◽  
Pitting Corrosion ◽  
Chloride Ion ◽  
Chloride Ions ◽  
304 Stainless Steel ◽  
Cr Content ◽  
Experiment Method ◽  
Ion Impact

The Mechanism of 304 Stainless Steel Pitting Corrosion Was Researched in Chloride Ions Environment. the Metallographic Microstructure of Areas near the Pitting Corrosion and Far Away from the Pitting Corrosion Were Observed by the Metallographic Experiment；Cr Content of the Sample Was Determined by EDXRF, to Prove Chloride Ion Impact on the Element Cr of 304 Stainless Steel. Finally, Corrosion Rate of Specimens Was Determined by Piecewise Experiment Method to Prove Otherness for Corrosion Rate in Different Period of 304 Stainless Steel in Chloride Ions Environment.

Study on Corrosion Behavior of the 304 Stainless Steel in the Heavy Oil with High Salt, High Sulfur and High Acid Value

2012 ◽  
Vol 252 ◽  
pp. 271-275 ◽  
Author(s):  
Xiao Hong Wang ◽  
Yu Wei ◽  
Chun Yun Shao ◽  
Yi Jun Shi ◽  
Wei Xue ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Product ◽  
Heavy Oil ◽  
Acid Value ◽  
High Salt ◽  
Water Soluble ◽  
Local Corrosion ◽  
304 Stainless Steel ◽  
Uniform Corrosion ◽  
High Acid

The uniform corrosion and localized corrosion of 304 stainless steel in heavy oil with high salt, high sulfur and high acid value were researched by weight loss method and electrochemical method. The corrosion morphology of samples with and without corrosion product films and the compositions of the corrosion product films were observed using SEM and EDS. The results show that the 304 stainless steel is inapplicable to the refinery equipment of this heavy oil because of the severe local corrosion even if the uniform corrosion rate is as low as 0.0107mm/a. The salt corrosion and sulfur corrosion occur on the local surface of 304 stainless steel because of the chloride ion formed by hydrolysis of salt in the small emulsifying water. The water soluble iron naphthenate produced by chemical reaction between naphthenic and ferrous sulfides impel the local corrosion of the 304 stainless steel.

Pitting corrosion and effect of Euphorbia echinus extract on the corrosion behavior of AISI 321 stainless steel in chlorinated acid

2019 ◽  
Vol 37 (3) ◽  
pp. 259-271 ◽  
Author(s):  
Y. Koumya ◽  
R. Idouhli ◽  
M. Khadiri ◽  
A. Abouelfida ◽  
A. Aityoub ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
Chloride Concentration ◽  
Analysis Data ◽  
Chloride Ions ◽  
General Corrosion ◽  
Visible Absorption ◽  
Pitting Potential ◽  
Aisi 321

AbstractStainless steel (SS) is a very corrosion-resistant alloy used in different industrial plants because of its chemical and mechanical properties. However, the high chloride concentration in sulfuric acid (H2SO4) may promote both general corrosion and pitting corrosion. The pitting corrosion susceptibility in SS in chlorinated H2SO4 and the effect of Euphorbia echinus extract (EEE) on both general corrosion and pitting corrosion have been studied using potentiodynamic polarization, electrochemical impedance spectroscopy, chronoamperometry, cyclic voltammetry, and scanning electron microscopy (SEM). The pitting potential has been found to shift slightly in the presence of chloride ions (Cl−) in H2SO4. Also, pitting corrosion initiation has been demonstrated in the recorded chronoamperograms as a linear straight line having a positive slope. EEE has reduced the general corrosion and the inhibitor adsorption was found to follow the Langmuir isotherm. SEM micrographs showed that the tested inhibitor has efficiently acted on pitting corrosion for different concentrations of Cl−. Also, the kinetic findings were in good agreement with the surface analysis data. Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectrophotometric measurements provided more insights on the interaction between the chemical functional groups of the inhibitor and the SS surface.

Atmospheric pitting corrosion of 304L stainless steel: the role of highly concentrated chloride solutions

2015 ◽  
Vol 180 ◽  
pp. 251-265 ◽  
Author(s):  
Steven R. Street ◽  
Na Mi ◽  
Angus J. M. C. Cook ◽  
Haval B. Mohammed-Ali ◽  
Liya Guo ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Large Data ◽  
304 Stainless Steel ◽  
Data Sets ◽  
304L Stainless Steel ◽  
Active Dissolution ◽  
Pitting Potential ◽  
Enhanced Dissolution ◽  
Heterogeneous Alloy

The morphology of atmospheric pitting corrosion in 304L stainless steel plate was analysed using MgCl2 droplets in relation to changes in relative humidity (RH) and chloride deposition density (CDD). It was found that highly reproducible morphologies occur that are distinct at different RH. Pitting at higher concentrations, i.e. lower RH, resulted in satellite pits forming around the perimeter of wide shallow dish regions. At higher RH, these satellite pits did not form and instead spiral attack into the shallow region was observed. Increasing CDD at saturation resulted in a very broad-mouthed pitting attack within the shallow dish region. Large data sets were used to find trends in pit size and morphology in what is essentially a heterogeneous alloy. Electrochemical experiments on 304 stainless steel wires in highly saturated solutions showed that the passive current density increased significantly above 3 M MgCl2 and the breakdown pitting potential dropped as the concentration increased. It is proposed that the shallow dish regions grow via enhanced dissolution of the passive film, whereas satellite pits and a spiral attack take place with active dissolution of bare metal surfaces.

scholarly journals Electrochemical behavior of two austenitic stainless steel biomaterials

2010 ◽  
Vol 63 (1) ◽  
pp. 159-166 ◽  
Author(s):  
Enrico J. Giordano ◽  
Neusa Alonso-Falleiros ◽  
Itamar Ferreira ◽  
Oscar Balancin
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Passive Film ◽  
Scratch Test ◽  
Localized Corrosion ◽  
Cyclic Polarization ◽  
High Tendency ◽  
Pitting Potential ◽  
Stable Growth ◽  
Corrosion Pits

Potentiodynamic and potentiostatic polarization measurements were conducted in 0.9% NaCl solution to investigate the localized corrosion susceptibility of two austenitic stainless steel biomaterials: a low nitrogen, according to ASTM F 138 - the metallic material most widely utilized today in orthopedic applications; and a nitrogen- and niobium-bearing stainless steel, according to ISO 5832-9, which has shown a promising potential as a substitute of the F 138 steel for more severe loading applications and longer times inside the human body. The polarization tests revealed that the ISO 5832-9 steel is more corrosion resistant than the F 138. The critical pitting potential of the ISO 5832-9 steel could not be observed in the cyclic polarization curve up to the value of potential corresponding to its transpassivity. The potentiostatic scratch test confirmed the superiority of the ISO 5832-9 steel, which heal the mechanically damaged passive film at applied potential as high as 800 mV (SCE). Scanning electron microscopy (SEM) examination confirmed the presence of corrosion pits - lacelike pits - in a stable growth stage on the surface of F 138 steel and the absence of such pits in the specimens of the ISO 5832-9 steel. The higher corrosion resistance of the latter is attributed to the increased stability of the passive film and the high tendency to repassivate, which, in turn, is favored by the presence of nitrogen in interstitial solid solution in the austenite of this type of steel.

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