This paper aims to investigate the corrosion mechanism of X90 pipeline steel under marine alternating dry/wet (ADW) environment and provide a scientific reference for the practical application of X90 grade high-strength low-alloy pipeline steel under marine environment.
The finite element analysis was used to determine the stress distribution of C-ring samples. The corrosion resistance of the X90 steel was characterized using the potentiodynamic polarization curve and electrochemical impedance spectroscopy measurements. The surface macroscopic and microscopic morphology of the rust layer were characterized by optical microscope and scanning electron microscope, respectively. The phase composition of the rust layer was characterized using X-ray diffraction. Energy spectrometer was used to detect the element distribution of the C-ring cross-section.
The corrosion behavior of X90 steel is affected by the blocking cell effect. The corrosion mechanism of X90 steel is the anodic dissolution dominated and hydrogen evolution assisted. The corrosion behavior of X90 pipeline steel is aggravated with the elongation of ADW cyclic time.
This study investigated the corrosion mechanism of X90 pipeline steel under marine ADW environment. There is no known scholar who conducted a research on the X90 grade pipeline steel corrosion issue in ADW conditions caused by spray splash zone. What’s more, the spray splash zone is precisely the area where the corrosion rate of metal materials is the fastest in marine environment. This paper can enrich the theoretical research on the corrosion of X90 pipeline steel in marine environment, and provide the theoretical basis for large-scale engineering application of X90 pipeline steel in the future.
