Ageing of the spontaneous passive state of 2304 duplex stainless steel in high-alkaline conditions with the presence of chloride

Abstract

A long-term electrochemical monitoring of the natural ageing of spontaneously passivated duplex 2304 stainless steel (SS) in the presence of increasing concentrations of chloride was carried out in the present work. The influence of the steel surface roughness on the SS pitting susceptibility was also assessed by comparing parent (P-SS) and cold-drawn (CD-SS) types. A different electrochemical response against the presence of chloride in the passive film/electrolyte interface was registered for both types of stainless steels: while a progressive destabilization of the passive layer for P-SS with pitting formation was observed at high concentrations of chloride (2 M), a more resistant behaviour against the chloride action was observed for the CD-SS, which presented a significant lower surface roughness.

Feasibility of utilizing 2304 duplex stainless steel rebar in seawater concrete: Passivation and corrosion behavior of steel rebar in simulated concrete environments

“…[30] In addition, steel rebar does not reach such a high potential level for normal application in concrete. [12,28,31] The rapid rise in current density after 0.6 V was not triggered by pitting corrosion because the current increase occurred even in the absence of chloride. In addition, gas generation occurred in this potential range of polarization.…”

“…The transpassive dissolution process with a high current density (approximately 10 µA/cm 2 ) does not require excessive attention because it is associated with the transport of oxidation products in passive film, and is not directly related to the dissolution of base metal . In addition, steel rebar does not reach such a high potential level for normal application in concrete …”

“…To quantify EIS results, the equivalent electrical circuit method has been widely used to analyze electrochemical behavior. [44,45] In previous studies, equivalent circuit models with one time [12,[46][47][48] and two-time duplex stainless steel in simulated deteriorating concrete pore solutions with different pH and chloride ion concentrations constants [12,14,29,31] were chosen to explain the impedance data for stainless steel in alkaline solutions. In this study, to directly compare the stability of the passive film during deterioration of the concrete, the equivalent electrical circuit with one time constant ( Figure 8) was used to fit all the experimental data.…”

“…In recent years, with the application of stainless steel rebar in concrete buildings, the corrosion behavior of various types of stainless steel (traditional austenitic stainless steel, duplex stainless steel, and even ferritic stainless steel) in simulated concrete environments has been studied extensively. However, most of these studies focused on the passivation and corrosion behavior of stainless steel in simulated concrete environments.…”

“…[21,22] Even if the steel rebar can form a perfect passive film during the concrete curing stage, whether the passive film can maintain stability during the long-term service stage is another factor that deserves attention. [16] In recent years, with the application of stainless steel rebar in concrete buildings, the corrosion behavior of various types of stainless steel (traditional austenitic stainless steel, [12,[23][24][25][26][27][28][29] duplex stainless steel, [10,12,14,24,[26][27][28][30][31][32] and even ferritic stainless steel [33] ) in simulated concrete environments has been studied extensively. However, most of these studies focused on the passivation and corrosion behavior of stainless steel in simulated concrete environments.…”