Investigation of the Localized Corrosion and Passive Behavior of Type 304 Stainless Steels with 0.2–1.8 wt % B

The pitting corrosion resistance and passive behavior of type 304 borated stainless steels (Febalance–18Cr–12Ni–1.5Mn–(0.19, 0.78, and 1.76 wt %)B) manufactured through conventional ingot metallurgy were investigated. The alloys were composed of an austenitic matrix and Cr2B phase, and the volume fraction of Cr2B increased from 1.68 to 22.66 vol % as the B content increased from 0.19 to 1.76 wt %. Potentiodynamic polarization tests measured in aqueous NaCl solutions revealed that the pitting corrosion resistance was reduced as the B content increased and the pits were initiated at the matrix adjacent to the Cr2B phase. It was found that the reduced resistance to pitting corrosion by B addition was due to the formation of more defective and thinner passive film and increased pit initiation sites in the matrix.

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The Effect of Alloying Cu on Pitting Corrosion Resistance of Copper-Bearing Ferritic Stainless Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.569.197 ◽

2008 ◽

Vol 569 ◽

pp. 197-200 ◽

Cited By ~ 1

Author(s):

Wei Zhang ◽

De Ning Zou ◽

Hong Hong Yao ◽

Jun Yang

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Pitting Corrosion ◽

Stainless Steels ◽

Antibacterial Properties ◽

Ferrite Matrix ◽

Localized Corrosion ◽

General Corrosion ◽

Pitting Corrosion Resistance ◽

Effect Of Alloying

Copper is a well-known alloying element which is used to improve the resistance to general corrosion of stainless steels. Our previous experiments show that the increase of copper content can acquire the excellent antibacterial properties and can also increase the tendency to cold formability of the ferritic stainless steels. However, the effect of alloying Cu on the resistance to localized corrosion has not been clarified sufficiently. In order to understand the effect of copper on pitting corrosion resistance of the ferritic antibacterial stainless steel, the electrochemical experiments were carried out and the anodic polarization curves were performed in 3.5% NaCl solution for two kinds of steels. The results reveal that the ε-Cu phase in ferrite matrix diminishes pitting corrosion resistance of the antibacterial stainless steel in the chlorides medium. It is connected with the poor passive behavior of the ε-Cu phase inclusions.

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Influences of Aging Precipitation on Corrosion Resistance of 18Cr-18Mn-2Mo-0.77N HNS

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1013 ◽

2009 ◽

Vol 79-82 ◽

pp. 1013-1016 ◽

Cited By ~ 1

Author(s):

Zu Rui Zhang ◽

Hua Bing Li ◽

Zhou Hua Jiang ◽

Zhen Li ◽

Bao Yu Xu

Keyword(s):

Corrosion Resistance ◽

Pitting Corrosion ◽

Volume Fraction ◽

Aging Treatment ◽

High Nitrogen ◽

Aging Precipitation ◽

Pitting Corrosion Resistance ◽

Nitrogen Steel ◽

The Matrix ◽

Nose Temperature

Influences of aging precipitation of Cr2N and Chi (χ) phases on the resistance to pitting corrosion and intergranular corrosion of 18Cr-18Mn-2Mo-0.77N high nitrogen steel (HNS) as a type of fundamental and structural materials were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) pattern and electrochemical methods. Intergranular, cellular Cr2N and χ phases precipitate gradually along grain boundaries and inward grains. The volume fraction of precipitation presents a C-curve with a nose temperature of 850°C during 2h aging treatment. The solution-treated (ST) HNS exhibits the highest pitting corrosion potential because of high nitrogen content in steel, and especially no precipitation. The pitting corrosion resistance of aged HNS decreases because of the formation of aging precipitation which results in the depletion of Cr and Mo in the matrix. The pitting corrosion potentials firstly decrease then increase as the same tendency as the amount of precipitation expect 850°C and 900°C. Double loop electrochemical potentiokinetic reaction (DL-EPR) results show that the change tendency of IGC susceptibility is well consistent with the amount of precipitation of aged HNS for 2h at various temperatures. With prolonging the aging time at 850°C, aged HNS presents more obviously intergranular sensitization due to the formation of aging precipitation which results in the depletion of Cr and Mo.

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Effect of Microalloy Elements on Corrosion Resistance of High-Chromium-Containing Ferritic Stainless Steels in Chloride Solutions

CORROSION ◽

10.5006/1.3290381 ◽

2001 ◽

Vol 57 (6) ◽

pp. 547-556 ◽

Cited By ~ 9

Author(s):

H. Kim ◽

Y-D. Lee

Keyword(s):

Corrosion Resistance ◽

Pitting Corrosion ◽

Stainless Steels ◽

Mechanical Damage ◽

Chemical Compositions ◽

Inclusion Type ◽

Electrochemical Tests ◽

Pitting Corrosion Resistance ◽

The Matrix ◽

The Difference

Abstract The effects of inclusions on corrosion resistance of high-Cr-containing ferritic steels were studied using electrochemical tests (anodic polarization and electrochemical noise [EN]) and a ferric chloride (FeCl3) test in chloride solution. For this purpose, the inclusion type and size in the matrix was controlled by the selective addition of alloying elements, their contents, and pickling treatment. Large inclusions such as titanium nitride (TiN), though chemically stable, caused surface cracks at the inclusion/matrix interface during mechanical treatments and decreased pitting corrosion resistance. Soluble inclusions located at the interface were preferentially attacked to form crevices even if the inclusions were as small as a submicron. Meanwhile, submicron inclusions such as Nb, C, or N did not affect pitting corrosion resistance. Unlike the chemical compositions and shape of inclusion, the surface area covered by inclusions did not affect pitting corrosion resistance. Hence, the main factor affecting corrosion resistance was the presence of a crevice, whether it was formed by dissolution or mechanical damage, and not the number of inclusions. EN testing revealed that the experimental alloys deoxidized by Si were more resistant to initial pitting corrosion resistance than those deoxidized by Al, though many steel manufacturers deoxidize stainless steels by Al. The discrepancy was attributed to the difference of the chemical stability and the feasability of crack formation depending on inclusion.

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