Effect of Cl- Concentration on Pitting Corrosion Property of Maraging Hardened Stainless Steel Based on Pourbaix Diagram

2018 ◽  
Vol 940 ◽  
pp. 59-64 ◽  
Author(s):  
Xin Zhang ◽  
De Ning Zou ◽  
Yu Qing Zhou ◽  
Xuan Na ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Corrosion Property ◽  
Ion Concentration ◽  
Pitting Potential ◽  
Pitting Corrosion Resistance ◽  
The Matrix ◽  
Simulation Results

The corrosion behavior of maraging hardened stainless steel (MHSS) in different Cl-medium was investigated by thermodynamics simulation and electrochemical experiments. The simulation results show that the thermodynamic stability zone decreases with the increase of the concentration of Cl-. Some of chromium transformed into Cr(OH)2+and adsorbed on the surface of stainless steel, and others generated Cr2O3protecting the matrix. Mo reacted with O2to form MoO42-adsorbed on the surface of the material, which inhibited the destruction of Cl-. The electrochemical experiments indicate that the concentration of Cl-is in the range of 2%-7%. The pitting potential and self-corrosion potential of MHSS decreased linearly with the increase of ion concentration, and the pitting corrosion resistance of MHSS decreased. When the self-corrosion current increases from 1.9888 μA to 2.6524 μA, the corrosion tendency of the material enhances.

Influences of Nitrogen Content and Aging Precipitates on Pitting Corrosion Resistance Properties of High Nitrogen Austenitic Stainless Steel

2013 ◽  
Vol 448-453 ◽  
pp. 102-106
Author(s):  
Zu Rui Zhang ◽  
Zhen Ye Zhao ◽  
Chun Zhi Li ◽  
Zhou Hua Jiang ◽  
Hua Bing Li
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Nitrogen Content ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
High Nitrogen ◽  
Pitting Corrosion Resistance ◽  
The Matrix ◽  
Nose Temperature

This study is concerning the influences of nitrogen content and aging precipitates on pitting corrosion resistance properties of high nitrogen austenitic stainless steel (HNS) through potentiodynamic polarization method. The microstructure of aged HNS is analized by scanning electron microscopy (SEM). The main results obtained are as follow: the formation of intergranular, cellular Cr2N and intermetallic χ precipitates makes the depletion of Cr and Mo in the matrix and deteriorates the resistance to pitting corrosion in aged specimens. Cr2N starts to precipitate in the form of lamellar structure to cellular precipitates, the pitting corrosion drops to about 0 VSCE. HNSs perform the same tendency that the pitting corrosion potential firstly decreases then increases and reduce to the minimum value at nose temperature. All the pitting corrosion potential of HNS-B aged for 2h at different temperature presents more than that of HNS-A. The pitting corrosion resistance is mainly controlled by nitrogen content before great precipitates of cellular Cr2N and intermetallic χ phase rich in Cr and Mo. It is also mainly controlled by the content and the type of precipitates after great precipitates of cellular Cr2N.

Influence of Sigma Phase Precipitation on Pitting Corrosion of 2507 Super-Duplex Stainless Steel

2010 ◽  
Vol 658 ◽  
pp. 380-383 ◽  
Author(s):  
Ying Han ◽  
De Ning Zou ◽  
Wei Zhang ◽  
Jun Hui Yu ◽  
Yuan Yuan Qiao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Ambient Temperature ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Super Duplex Stainless Steel ◽  
Phase Precipitation ◽  
Pitting Potential ◽  
Σ Phase ◽  
Pitting Corrosion Resistance

Specimens of 2507 super-duplex stainless steel aging at 850°C for 5 min, 15 min and 60 min were investigated to evaluate the pitting corrosion resistance in 3.5% NaCl solution at 30°C and 50°C. The results are correlated with the microstructures obtained with different aging time. The precipitation of σ phase remarkably decreases the pitting corrosion resistance of the steel and the specimen aged for 60 min presents the lowest pitting potential at both 30°C and 50°C. With increasing the ambient temperature from 30°C to 50°C, the pitting potential exhibits a reduction tendency, while this tendency is less obviously in enhancing the ambient temperature than in extending the isothermal aging duration from 5 to 60 min. SEM analysis shows that the surrounding regions of σ phase are the preferable sites for the formation of corrosion pits which grew up subsequently. This may be attributed to the lower content of corrosion resistance elements in these regions formatted with σ phase precipitation.

scholarly journals Pitting Corrosion Resistance on Annealing Treated Super Duplex Stainless Steel S32750

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 294
Author(s):  
Shuang Liu ◽  
Chaohua Yue ◽  
Xi Chen ◽  
Qiuhua Zhu ◽  
Yiyou Tu
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Annealing Temperature ◽  
Super Duplex Stainless Steel ◽  
Boundary Area ◽  
Pitting Potential ◽  
Pitting Corrosion Resistance ◽  
Equivalent Number

The pitting corrosion resistance of S32750 super duplex stainless steel, annealing treated at temperatures of 950–1200 °C for 20–60 min, was investigated using potentiodynamic polarization tests. The results show that the volume fractions of ferrite in the S32750 duplex stainless steel increased from 48.9% to 68.4% as annealing temperatures increased from 950 to 1200 °C. The pitting potential of the sample increased first and then decreased from an annealing temperature of 950 to 1050 °C, and the highest pitting potential was observed after annealing at 1050 °C for 35 min. The pitting corrosion resistance of S32750 stainless steel is due to the combination of pitting resistance equivalent number (PREN) value, phase fraction and grain boundary area fraction, and the imbalance of corrosion potential.

Corrosion Behavior of Ceramic Dispersion Strengthened High-Cr Stainless Steel

2008 ◽  
Vol 135 ◽  
pp. 127-130
Author(s):  
Gyoung Ja Lee ◽  
Sang Hoon Lee ◽  
Sung Mo Hong ◽  
Byung Sun Han ◽  
Jin Ju Park ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Potentiodynamic Polarization ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
High Energy ◽  
Polarization Curves ◽  
Pitting Potential ◽  
Potentiodynamic Polarization Curves ◽  
High Energy Ball Mill ◽  
Energy Ball

In the present work, corrosion characteristics of ceramic dispersion strengthened (CDS) high-Cr stainless steel (SS) has been investigated. For the preparation of CDS SS with uniformly distributed reinforcements, TiC particles were mechanically activated with Cu powder by using high-energy ball mill machine, and then Cu-coated TiC particles were mixed with molten SS. Potentiodynamic polarization curves were experimentally measured on unmodified SS and CDS SS in 0.05 M NaCl solution. The values of corrosion potential Ecorr, corrosion current io, pitting potential Epit and polarization resistance Rp were quantitatively determined from the measured potentiodynamic polarization curves. From the result, it is concluded that CDS SS exhibits higher corrosion resistivity than unmodified SS.

An Electrochemical Study Of Pitting Corrosion in Stainless Steels (Part 1—Pit Growth)

CORROSION ◽  
1959 ◽  
Vol 15 (1) ◽  
pp. 48-54 ◽  
Author(s):  
N. D. GREENE ◽  
M. G. FONTANA
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Stainless Steels ◽  
Chloride Ion ◽  
Corrosion Current ◽  
Ion Concentration ◽  
Solution Composition ◽  
Current Interruption ◽  
Percent Nickel ◽  
First Time

Abstract By means of a unique artificial pit specimen, pit growth on 18 percent chromium-8 percent nickel stainless steel has been measured and characterized. The effects of solution composition, agitation, atmosphere, corrosion current interruption, chloride ion concentration, and inhibitor additions have been investigated. Pit interaction during pit growth has also been determined. The autocatalytic nature of pitting has been verified, and evidence of ion screening at pit sites has been experimentally observed for the first time. 3.2.2

scholarly journals Intergranular and Pitting Corrosion in Sensitized and Unsensitized 20Cr-25Ni-Nb Austenitic Stainless Steel

CORROSION ◽  
10.5006/3725 ◽  
2021 ◽  
Author(s):  
Ronald Clark ◽  
Choen Chan ◽  
W. Walters ◽  
Dirk Engelberg ◽  
Geraint Williams
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Pitting Corrosion ◽  
Intergranular Corrosion ◽  
Niobium Carbide ◽  
Ion Concentration ◽  
Kelvin Probe ◽  
The Matrix

Advanced gas-cooled reactor (AGR) oxide fuels used in the UK are clad in bespoke grade 20%Cr-25%Ni-Nb austenitic stainless steel. Electrochemistry was first applied to correlate the breakdown potential with chloride ion concentration, temperature and pH for this alloy. At near-neutral pH the unsensitized material exhibited a linear E<sub>b</sub> = A + B log10[Cl<sup>-</sup>] relationship, where A = 0.7 V (vs. SCE), and B = 0.098 V/decade. Scanning Kelvin probe force microscopy revealed grain boundary regions in the heat-treated material up to 65 mV less noble to the matrix, whereas un-dissolved niobium carbide (NbC) precipitates were up to 55 mV more noble to the matrix. In-situ time-lapse microscopy and post-corrosion observations confirmed that sensitized grain boundaries were susceptible to pitting corrosion, further developing along intergranular corrosion pathways. It has however been shown that micro galvanic coupling between the Nb precipitates and matrix and / or sensitized grain boundary regions is not a factor in corrosion initiation as all experiments were performed under external potential control. Post corrosion observations showed the presence of pits at NbC precipitates promoting grain boundary corrosion. It is postulated that corrosion initiates at NbC precipitates as a pit, and when in close vicinity to Cr-depleted grain boundaries, then propagates along grain boundaries as intergranular corrosion.

Pitting corrosion of super martensitic stainless steel 00Cr13Ni5Mo2

2014 ◽  
Vol 61 (6) ◽  
pp. 387-394 ◽  
Author(s):  
J.L. Li ◽  
C.T. Qu ◽  
S.D. Zhu ◽  
L. Liu ◽  
Z.Q. Gao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Martensitic Stainless Steel ◽  
Pitting Potential ◽  
Content Type ◽  
Pitting Corrosion Resistance ◽  
Super Martensitic Stainless Steel ◽  
The Difference ◽  
Made In

Purpose – The purpose of this study was to investigate the pitting resistance and assess the critical pitting temperature (CPT) of a super martensitic stainless steel, 00Cr13Ni5Mo2, made in China, considering especially the difference in the pitting corrosion resistance between the domestic super martensitic stainless steel and an imported one. Design/methodology/approach – Potentiodynamic sweep tests were applied to investigate the effects of four NaCl concentrations (weight per cent) of 1, 3.5, 9 and 17, and four testing temperatures of 30, 50, 75 and 90°C on the pitting resistance of the domestic super martensitic stainless steel in the presence of CO2. Potentiostatic sweep tests were utilized to determine the CPT. Furthermore, chemical immersion exposures, implemented according to the appropriate standard were used to evaluate the difference in the pitting corrosion resistance between the domestic super martensitic stainless steel and an imported one. In addition, the morphology of pits was analyzed using a scanning electron microscope. Finding – The pitting potential of the domestic super martensitic stainless steel decreased with an increase in NaCl concentration and temperature in the presence of CO2. The CPT of the domestic super martensitic stainless steel measured by potentiostatic polarization was 41.16°C. Two types of typical corrosion pits, closed pits formed at 35°C and open pits formed at 50°C, were observed. Furthermore, compared to the super martensitic stainless steel made in Japan, the domestic one was better in terms of pitting potential, corrosion rate and the density of the pits, but worse in terms of the depth of the pits, which may result in a risk of corrosion perforation of tubing and casings. Originality/value – The paper highlights that chloride ions, temperature and the presence of CO2 play an important role on the pitting resistance of super martensitic stainless steel.

Effect of Chloric Ions and Temperature on the Pitting Corrosion Behavior of Supermartensitic Stainless Steel in CO2-Saturated Chloride Solution

2012 ◽  
Vol 538-541 ◽  
pp. 2342-2345
Author(s):  
Jun Li ◽  
Dong Ye ◽  
Yong Mei Chen ◽  
Jie Su ◽  
Kun Yu Zhao
Keyword(s):  
Stainless Steel ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Chloride Solution ◽  
Polarization Measurement ◽  
Ion Concentration ◽  
Pitting Potential ◽  
Supermartensitic Stainless Steel ◽  
Different Temperatures ◽  
Logarithmic Relation

Abstract. The pitting corrosion behavior of two kinds (W and Cu-free; W and Cu-bearing) of supermartensitic stainless steels (SMSS) were studied in CO2-saturated chloride solution with three chloric ion concentration: 21200, 50000, 100000ppm, and four different temperatures:19, 40, 60, 80°C by potentiodynamic polarization measurement. The results indicate that the pitting potential decreased with temperature increasing, and in a logarithmic relation with the chlorine concentration in both alloys. The pitting potential of supermartensitic stainless steel is increased by together adding tungsten and copper.

Electrochemical studies on pitting corrosion of tin in sodium borate solutions containing nitrate ions

2019 ◽  
Vol 66 (3) ◽  
pp. 300-306
Author(s):  
Nobl Foad El Boraei ◽  
Sayed S. Abd El Rehim ◽  
Hamdy H. Hassan
Keyword(s):  
Pitting Corrosion ◽  
Electrochemical Behavior ◽  
Nitrate Solution ◽  
Ion Concentration ◽  
Sodium Borate ◽  
Pitting Potential ◽  
Content Type ◽  
Pitting Corrosion Resistance ◽  
Passive Transition ◽  
Passive Oxide Film

Purpose The purpose of this paper is to study the electrochemical behavior of Sn electrode in Na2B2O7 solutions in the absence and presence of NaNO3 as a pitting corrosion agent. Design/methodology/approach The electrochemical behavior of Sn electrode was studied by using cyclic voltammetry and potentiodynamic polarization measurements and complemented with scanning electron microscopy examinations. Findings This paper shows that in the absence of NO3 − ions, the anodic polarization of Sn electrode exhibits active/passive transition. Addition of various concentrations of NO3 − anions to the borate solution enhances active anodic dissolution and tends to break down the passive oxide film at a certain pitting potential. The pitting potential, and hence the pitting corrosion resistance, decreases with increasing NO3-ion concentration and temperature but increases with scan rate and repetitive cycling. Addition of CrO42−, WO42− or MoO42− oxyanions to the borate nitrate solution inhibits the pitting corrosion of Sn. Originality/value This is the first study that shows the effect of NO3 − ion as a pitting corrosion agent.

Influence of MoSi2 Addition in Co Based Alloy Cladding Coating on Microstructure Evolution and Pitting Corrosion Behaviour

2013 ◽  
Vol 456 ◽  
pp. 392-398
Author(s):  
Ze Fen Liang ◽  
Min Zheng
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Stainless Steel Substrate ◽  
Corrosion Behaviour ◽  
Steel Substrate ◽  
304 Stainless Steel ◽  
Pitting Potential ◽  
Pitting Corrosion Resistance ◽  
Coating Microstructure

In the present paper the influence of the addition of MoSi2particles on the microstructure and pitting corrosion behaviour of laser cladding Co based alloy coatings deposited on 304 stainless steel substrate has been reported. The coating microstructure was investigated by SEM, OM, XRD and EPMA etc.. And the pitting corrosion resistance of coating was evaluated in the 3.5% NaCl solution. The results showed that: (1) The microstructure is fined by increasing MoSi2percentage. And the coating microstructure evolved from dendrites and interdendritic eutectics to various faceted dendrites with the bamboo leaf, flower, or butterfly morphology, when the MoSi2content is from 0~20% to 30~40%; (2) the (Epit-Eprot) of Co based alloy/MoSi2composite coating was lower than that of Co based alloy, and which presented higher self-repairing capability. The pitting potential Epitof Co +(0~20wt.%) MoSi2cladding coatings is higher than that of stainless steel, the pitting corrosion resistance is enhanced; When more MoSi2(30wt.%) was added, the pitting corrosion resistance decreases due to microstructure inhomogeneity and exiting of inclusion.

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