Enhancement of Corrosion Properties of Fe-18Cr-9Mn-5.5Ni-0.3(C + N) Austenitic Stainless Steels by Carbon Alloying

In this study, the resistance to pitting corrosion of Fe-18Cr-9Mn-5.5Ni-0.3(C + N) austenitic stainless steel γ-SSs (in wt%) with different C/(C + N) ratios (0.02, 0.29, and 0.60) was evaluated. It was found to be difficult to form a γ-matrix without precipitation, because the Cr23C6 precipitation rate in the γ-SSs with the C/(C + N) value of 0.60 was too fast. Thus, it was recommended to maintain the C/(C + N) ratio below 0.6 in Fe-18Cr-9Mn-5.5Ni-0.3(C + N) γ-SSs. As a result of the potentiodynamic polarization tests, the γ-SS with a C/(C + N) ratio of 0.29 showed the highest resistance to pitting corrosion, and the resistance level of this alloy was superior to that of the AISI 304 γ-SS. Analysis of the passive film and matrix dissolution rates revealed that a higher C/(C + N) ratio of γ-SS increased the protective ability of the passive film and decreased the growth rate of the pits. Therefore, it could be concluded that partial substitution of C for N was advantageous for improving the pitting corrosion resistance of Fe-18Cr-9Mn-5.5Ni-0.3(C + N) γ-SSs, as long as C and N existed in a solid solution state.

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Molybdenum Effects on Pitting Corrosion Resistance of FeCrMnMoNC Austenitic Stainless Steels

Metals ◽

10.3390/met8080653 ◽

2018 ◽

Vol 8 (8) ◽

pp. 653 ◽

Cited By ~ 17

Author(s):

Heon-Young Ha ◽

Tae-Ho Lee ◽

Jee-Hwan Bae ◽

Dong Chun

Keyword(s):

Corrosion Resistance ◽

Passive Film ◽

Point Defects ◽

Pitting Corrosion ◽

Stainless Steels ◽

Austenitic Stainless Steels ◽

Passive State ◽

Film Resistance ◽

Pitting Corrosion Resistance ◽

Mo Content

For Fe-based 18Cr10Mn0.4N0.5C(0–2.17)Mo (in wt %) austenitic stainless steels, effects of Mo on pitting corrosion resistance and the improvement mechanism were investigated. Alloying Mo increased pitting and repassivation potentials and enhanced the passive film resistance by decreasing number of point defects in the film. In addition, Mo reduced critical dissolution rate of the alloys in acidified chloride solutions, and the alloy with higher Mo content could remain in the passive state in stronger acid. Thus, it was concluded that the alloying Mo enhanced pitting corrosion resistance of the alloys through increasing protectiveness of passive film and lowering pit growth rate.

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Effect of Rare Earth on the Inclusions and Pitting Resistance of Austenitic Stainless Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.718-720.29 ◽

2013 ◽

Vol 718-720 ◽

pp. 29-32 ◽

Cited By ~ 1

Author(s):

Xiao Liu ◽

Yu Bo

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Rare Earth ◽

Austenitic Stainless Steel ◽

Pitting Corrosion ◽

Stainless Steels ◽

Anodic Polarization ◽

Austenitic Stainless Steels ◽

Metallographic Examination ◽

Pitting Corrosion Resistance

The anodic polarization curves of 21Cr-11Ni austenitic stainless steels with various RE contents in 3.5% NaCl neutral solutions have been measured by electrochemical methods. The effect of RE on pitting corrosion resistance of 21Cr-11Ni stainless steels has been studied by the metallographic examination. The results show that sulfide and other irregular inclusions are modified to round or oval-shaped RE2O2S and RES after adding RE to 21Cr-11Ni stainless steesl. RE makes sulfide, and other irregular inclusions change to dispersed round or oval-shaped RE inclusions, effectively inhibits the occurrence of pitting corrosion, thereby enhancing the corrosion resistance of 21Cr-11Ni austenitic stainless steels.

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