Abstract
The influence of surface roughness on the pitting corrosion behaviour of 2205 duplex stainless steel (DSS) in a chloride-containing environment was investigated using electrochemical noise (EN) techniques and morphology observation. A rougher surface condition increased the frequency of pit initiation because of the increase in more occluded pit sites. Rough surface finish also accelerated pit growth by increasing the actual dissolution rate in the pit. Metastable pits on rougher surfaces had longer lifetimes and grew to larger sizes, as their inner chemical environment was more easily maintained. However back-scatter images showed that pitting initiates on DSS 2205 regardless of the roughness condition.
Highlights
Duplex stainless steel (DSS) is the dual-phase structure stainless steel that contains almost equal contents of ferrite and austenite and has been widely applied in the marine and petroleum industries [1,2]
A smoother surface finish reduces the incidence of metastable pitting and increases the pitting potential of austenite stainless steel in chloride solution, but it is doubted whether the conclusion can be fully extended to DSS
The metastable/stable pit initiation and growth on DSS are obviously affected by surface condition and were similar to those on austenite
Summary
Duplex stainless steel (DSS) is the dual-phase structure stainless steel that contains almost equal contents of ferrite and austenite and has been widely applied in the marine and petroleum industries [1,2]. The influence of surface roughness on metastable pitting, critical pitting temperature (CPT), and pitting potential of austenite stainless steel has been studied [5,6]. The specific effect of surface roughness on pitting initiation and growth stage on stainless steel is seldom reported. In contrast to conventional electrochemical techniques, EN measurement does not require excitation signals Because of these advantages, EN signals are widely accepted in the monitoring of localized corrosion of metallic materials [10,11,12]. Observed that a strong cathodic process can change the amplitude of EN signals arising from pitting corrosion in stainless steel. The object to study the influence ofElectrochemical surface roughness onmeasurement the initiation and early stage of the growth processwas of pitting corrosion in DSS.
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