Austenitic and Ferritic Stainless Steels

Pitting corrosion of food grade ferritic stainless steel AISI‐430 was studied in 20% aqueous acetic acid solution containing 0.5 M NaCl. Potentiodynamic polarization measurements at a slow scan rate reveal formation of metastable pits and repassivation. Surface analysis reveals remnants of the passive oxide layer adhered along the circumference of the pits, evidences of loss of microcrystallites, no significant loss in crystallinity during corrosion process and formation of mixed oxides of iron and chromium. The pitting of ferritic steel is an autocatalytic process, and the proposed mechanism suggests that both chloride and acetate ions play important role.

Section: Surface Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrochemical, surface analytical, and spectroscopic study of passive film and pits formation on food grade ferritic stainless steel AISI‐430 in aqueous acetic acid containing chloride ions

Mahato

Cho

Singh

2018

Influence of the welding current intensity and nitrogen content on the corrosion resistance of austenitic stainless steels

Jegdić

Bobić

Radojković

et al. 2018

The resistance to pitting and intergranular corrosion of the welded joint of X5CrNi18‐10 austenitic stainless steel is analyzed in this paper. The resistance of the welded joint to intergranular corrosion does not depend on the nitrogen content in the shielding gas. It depends on the heat input into the welded joint, that is, on the welding current intensity. The resistance to pitting corrosion depends on the content of nitrogen in the shielding gas and on the welding current intensity. With the increase in the nitrogen content in the shielding gas, the resistance of the heat affected zone (HAZ) to pitting corrosion increases. The welding current intensity (heat input into the welded joint) shows two opposite effects. On the one hand, the increase of the heat input into the welded joint causes a more intensive precipitation of chromium carbides along the grain boundaries, which then leads to depletion in chromium of the grain boundary areas. The sensitization degree of the HAZ is thus increased and the formation of pits easier. On the other hand, with the increase in the welding current intensity, diffusion of nitrogen from the weld metal into the HAZ is facilitated, which contributes to the increased HAZ resistance to pitting corrosion. Possible mechanisms for increasing the HAZ resistance to pitting corrosion in the presence of nitrogen are also considered.

Corrosion behaviour of AA2024 aluminium alloy in different tempers in NaCl solution and with the CeCl₃ corrosion inhibitor

Jegdić

Bobić

Linić

2019

The paper analyses the corrosion behaviour of naturally and artificially aged AA2024 alloy in NaCl solution and in the presence of an environment‐friendly corrosion inhibitor, CeCl3. On the basis of the values of polarisation resistance and corrosion current density, the corrosion resistance of the protective inhibitor film is established as well as the general corrosion resistance of this aluminium alloy. Resistance to pit formation is determined based on the difference in pitting and corrosion potentials while resistance to pit growth is determined based on the amount of charge consumed during pit growth. A scanning electron microscope is used to examine the morphology of the pits formed during the pitting corrosion testing, as well as to determine the cerium content on intermetallic particles and the matrix AA2024 alloy. The corrosion behaviour of AA2024 alloy is investigated after different test periods in NaCl solution and in the same solution with the CeCl3 inhibitor. The corrosion resistance of both tempers of AA2024 alloy is more than one order of magnitude higher in the presence of CeCl3. An explanation of the observed differences in the corrosion behaviour of the naturally and artificially aged AA2024 alloy is proposed. Different corrosion behaviour of the alloy after different test periods is also explained.