Pitting Corrosion Resistance of Mn‐Alloyed Austenitic Stainless Steels

Abstract

The aim of the study was to examine the role of composition, inclusions, and precipitates on the pitting corrosion resistance of Mn-alloyed austenitic stainless steels. The pitting corrosion measurements were conducted in three electrolytes: sea water (3.56 wt% NaCl), sulfuric acid (0.5M H 2 SO 4 ), and sulfuric acid þ salt (0.5 M H 2 SO 4 þ 0.4 M NaCl) solutions. In the tests, it was observed that manganese sulfides act as corrosion pit initiators. As the Cr content was decreased and Ni partially replaced by Mn, the pitting corrosion resistance was reduced in seawater and H 2 SO 4 þ NaCl solutions. On the other hand, the amount of inclusions was not found to have a clear correlation to the potential at which the corrosion pits initiate. In the sulfuric acid solution, no pitting was observed and all the materials exhibited similar behavior in the passive range. However, in the transpassive range the dissolution rate of AISI 304 steel was greatest, whereas more Mn and less Ni and Cr containing steels exhibited a secondary passivation behavior.

Corrosion Investigation of Duplex Stainless Steels in Chlorinated Solutions

“…The alloy composition, sample microstructure, composition of the testing media and temperature are known to influence the pitting corrosion of stainless steels . Among these factors, the presence of impurity inclusions such as MnS, are known to trigger pitting corrosion due to the effect of specific dissolution products of the sulfides . Moreover, studies in chloride‐containing solutions show that the first step prior to pitting propagation is the dissolution of sulphide inclusions …”

Effect of Pulsed Current Gas Tungsten Arc Process on the Dissimilar Weldments between Nickel-based Superalloy/Austenitic Stainless Steel

“…6) and was found to be comparatively insignificant compared to conventional GTAW process which results in higher degree of segregation and hence reduced corrosion resistance. 8,53,54) Moreover, the passivation behaviour in the anodic branch of polarization curve for Grade 321 BM could be attributed to the presence of higher content of Cr (compared to Superalloy C-276 and filler wire). [55][56][57] Although, Grade 321 being a cost-effective (lesser alloyed) material compared to Superalloy C-276, its anodic branch had shown considerable passivation behaviour.…”