Initial Corrosion Behavior of 550NH Weathering Steel in Three Typical Atmospheric Environments

Abstract

According to the climatic characteristics of different regions in the Guangxi Zhuang autonomous region, the initial corrosion behavior of weathering resistant steel was studied in urban, industrial and coastal three typical atmospheric environments. The corrosion resistance of 550NH weathering steel with a strength level of 550 MPa was assessed through atmospheric exposure corrosion tests and electrochemical measurements. Results showed that the corrosion rate of 550NH weathering steel successively increased in urban, industrial and coastal environments. After six months of corrosion in three locations, the main corrosion products of 550NH weathering steel were identified as Fe3O4, α-FeOOH and γ-FeOOH. The corrosion product layer, being dense and devoid of penetrating cracks, was primarily attributed to the reparative effects of Cu and Cr elements on cracks and voids in 550NH weathering steel. With the extension of corrosion time, the electrochemical impedance spectra of 550NH in simulated marine and simulated industrial environments gradually transitioned from a single capacitive arc to a configuration of two capacitive arcs.

Keywords

• 550nh weathering steel; atmospheric environment; initial corrosion behavior; electrochemical impedance