Electron Microprobe Study of the Effect of Sulphide Inclusions on the Nucleation of Corrosion Pits in Stainless Steels

Szklarska‐Śmiałowska, Z.; Szummer, A.; Janik‐Czachor, M.

doi:10.1179/000705970798324540

Cited by 58 publications

(18 citation statements)

References 6 publications

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“…In addition, the shape of sulfide inclusions is also an important factor influencing the EAC because the inclusion shape closely affects the shape of pits or fissures, in turn the environment inside them. It has been proven that aggressive environment may be more easily maintained in deep narrow pits than shallow hemispherical ones [41]. In this context, the stringer-like or rod-like inclusions are more effective to initiate the EAC than the round ones.…”

Section: Discussionmentioning

confidence: 99%

Inclusion‐involved fatigue cracking in high temperature water

Katada

2005

Materials & Corrosion

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The nonmetallic inclusions in low-alloy pressure vessel steel A533B were carefully examined and the low cycle fatigue (LCF) behavior of the steel was investigated in 288 8C air and water. Much attention was paid to the roles of inclusions on fatigue crack initiation and propagation in high temperature water. Three types of inclusions were observed in the steel, consisting of isolated or clustered sulfide inclusions, duplex oxide-sulfide inclusions and isolated oxide inclusions. In high temperature air, fatigue cracks initiated predominantly from subsurface inclusions. In high temperature water, however, fatigue cracks initiated primarily at corrosion pits on the specimen surfaces resulted mainly from the dissolution of large or clustered sulfide inclusions. The subsurface and bulk inclusions also contributed to the fatigue cracking in high temperature water. Possible influence of the above three types of inclusions on environmentally assisted cracking (EAC) was evaluated. The fatigue fractographic features suggested a synergism between sulfide inclusions and hydrogen-induced cracking dominate the present EAC in high temperature water.

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Section: Discussionmentioning

confidence: 99%

Inclusion‐involved fatigue cracking in high temperature water

Katada

2005

Materials & Corrosion

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“…14 The inclusions in these experimental heats were dominated by large (> 8 µ m) chromium and manganese oxides and somewhat smaller, fine niobium nitrides and carbides. Several experimental alloys (Table 4) contained aluminum at low levels to control residual oxygen and produce low inclusion-area (clean) steels, which were less subject to pitting.…”

Section: Inclusion Distribution and Alloying (Aluminum)mentioning

confidence: 99%

Effect of Alloying Elements and Residuals on Corrosion Resistance of Type 444 Stainless Steel

Dowling¹,

Kim²,

Ahn³

et al. 1999

CORROSION

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The principal criteria for the corrosion resistance of intermediate-grade ferritic stainless steels (SS) were examined in a neutral chloride (Cl -) solution. The effect of increasing quantities of chromium and molybdenum was estimated for several heats in terms of the breakdown potential (E b ). The effect of inclusions (particularly the oxide-sulfide type) in type 444 SS ([UNS S44400] 19% Cr-2% Mo-Nb or 19% Cr-2% Mo alloy), combined with the alloying element trend, permitted derivation of an expression that integrated both phenomena. The expression represents the mutually opposing effects of the chromium/molybdenum passive film reinforcement as represented by the pitting resistance equivalent number (PREN), as well as incorporating the deleterious contribution of the inclusion density (⌿, /mm 2 ). Aluminum reduced the total inclusion content, which was associated with an increase in E b . Since no aluminum was detected in the passive film of high aluminum steels, it appeared likely that the prime effect of this element on corrosion resistance was via inclusion suppression. Corrosion studies of welded type 444 SS demonstrated that dual stabilization with low individual concentrations of titanium and niobium provided optimum corrosion resistance. This apparent synergism of niobium and titanium was independent of the surface of the welded materials, which were examined in the as-received, pickled, or polished states. The effect of the surface state in all cases was shown to exercise a critical effect on passive behavior.

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“…17 In contrast, Szklarska-Smialowska reported that oxide inclusions were not pit initiation sites. 16 In this research, the effects of microalloy elements (Si, Ti, Nb, Al, and Ca) and surface treatments (e.g., pickling and polishing) on corrosion resistance of ferritic stainless steels, in terms of their effects of on inclusions, were studied using electrochemical tests (the anodic polarization test and the electrochemical noise [EN] test) and the ferric chloride (FeCl 3 ) test (ASTM G 48D) (2) . In addition, electron microscopies were taken to identify the inclusions that affect pitting corrosion.…”

Section: Uns Numbers Are Listed In Metals and Alloys In The Unifiedmentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12] However, the effects of other types of inclusions such as oxides, carbide, and nitrides on pitting corrosion have been studied only by a few workers. [13][14][15][16] Barbosa reported that the pitting corrosion in Type 316 (UNS S31600) (1) was initiated at Al 2 O 3 particle sites after sulfide inclusions were removed by a pickling treatment with a dilute nitric acid (HNO 3 ) solution. 14 Srivastava proposed that Ti inclusions behaved cathodically with respect to the adjacent matrix.…”

Section: Uns Numbers Are Listed In Metals and Alloys In The Unifiedmentioning

confidence: 99%

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

Kim

Lee

2001

Corrosion

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The effects of inclusions on corrosion resistance of high-Crcontaining ferritic steels were studied using electrochemical tests (anodic polarization and electrochemical noise [EN]) and a ferric chloride (FeCl 3 ) 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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Electron Microprobe Study of the Effect of Sulphide Inclusions on the Nucleation of Corrosion Pits in Stainless Steels

Cited by 58 publications

References 6 publications

Inclusion‐involved fatigue cracking in high temperature water

Inclusion‐involved fatigue cracking in high temperature water

Effect of Alloying Elements and Residuals on Corrosion Resistance of Type 444 Stainless Steel

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

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