Effect of relative humidity on corrosion of Q235 carbon steel under thin electrolyte layer in simulated marine atmosphere

Abstract

Purpose The purpose of this paper is to obtain the environmental factor, which has the greatest effect on the corrosion rate of Q235 carbon steel under thin electrolyte layer, and to analyze the effect of this factor on the corrosion morphology, corrosion products and polarization process of Q235 carbon steel. Design/methodology/approach An electrochemical device, which can be used under thin electrolyte layer is designed to measure the corrosion current in different environments. Response surface methodology (RSM) is introduced to analyze the effect of environmental factors on corrosion rate. Scanning electron microscope (SEM) and X-ray diffraction (XRD) technique are used to analyze the results. The Tafel slopes of anode and cathode in different humidity and solution are calculated by least square method. Findings The three environmental factors are ranked according to importance, namely, humidity, temperature and chloride ion deposition rate. In a high humidity environment, the relative content of α-FeOOH in the corrosion product is high and the relative content of β-FeOOH is low. The higher the humidity, the lower the degree of anodic blockage, whereas the degree of cathodic blockage is independent of humidity. The above experiments confirm the effectiveness and efficiency of the device, indicating it can be used for the screening of corrosive environmental factors. Originality/value In this paper, an electrochemical device under thin film is designed, which can simulate atmospheric corrosion well. Subsequent SEM and XRD confirmed the reliability of the data measured by this device. The introduction of a scientific RSM can overcome the limitations of orthogonal experiments and more specifically and intuitively analyze the effects of environmental factors on corrosion rates.

Corrosion behaviour of carbon steel in Beibu Gulf tidal zone

“…Under the exposure to the marine environment, complex electrochemical reactions on the steel happen. When CS is exposed to moist air or seawater, an oxidation–reduction reaction occurs with iron and oxygen as the anode and the cathode, respectively [22,32]. The corrosion process of steel is as follows: …”

“…However, most of the studies on the corrosion mechanism of steel have focused on explaining results with the accelerated tests [20][21][22][23] and have been less previous evidence from the field tests, especially in the tidal zone. Thus it is indispensable to explore the corrosion behaviour of CS with field tests in the tidal zone.…”

Corrosion performance and morphological analysis of activated zinc phosphate coating formed on steel surface

“…This shift depends largely on the phosphate layer weight and its porosity (Tamilselvi et al , 2015; Zhang et al , 2015). As the corrosion process is an electrochemical cell, the lower corrosion current density means the lower corrosion rate and higher corrosion resistance (Song et al , 2020). The corrosion current density was 1.17 µA/cm 2 of activated layer with 1 g/L of copper acetate, whereas it was 2.88 and 2.95 µA/cm 2 of activated layer with 5 and 10 g/L of copper acetate solution, respectively.…”

Effect of ultraviolet light on the corrosion behavior of weathering steel in simulated marine atmospheric environment

“…The weathering steel is a key supporting role in the construction of artificial islands, railways, sea-crossing bridges and so on (Yang et al , 2021; Urban et al , 2017), and the demand for weathering steel in marine and industrial environments is increasing (Hu et al , 2022; Xia et al , 2022). However, weathering steel is prone to corrosion in the marine atmospheric environment with high humidity, high salinity and strong ultraviolet (UV) light (Morcillo et al , 2014; Song et al , 2020; Ahmad et al , 2000). Therefore, it is important to study the corrosion behavior of weathering steel in simulated marine atmospheric environment.…”