Multi-scale interrogation of magnetic field-dependent corrosion mechanism in Q355B steel by experimental-computational coupled framework

As an important material widely applied in engineering structures, Q355B steel is often subjected to the synergistic magnetic field-dependent (MF) and corrosive environment. The influence mechanism of MF on the corrosion behavior of Q355B steel presents unresolved complexities. The quantitative relationship between MF strength, direction and corrosion morphology, corrosion rate remains inadequately resolved. This study employed an experimental-computational coupled framework to systematically investigate the corrosion behavior of Q355B steel under varying MF strengths and elucidate the underlying mechanisms. An adjustable quantitative magnetic field strength device (AQMFSD) was developed to investigate the macroscopic corrosion morphology of Q355B steel in various MF-corrosion coupling environments through electrochemical corrosion test. The mechanism of the MF-dependent on corrosion was examined by COMSOL multi-physics field simulation software. The Q355B steel corrosion mechanism in MF was analyzed from micro-scale and macro-scale. The results showed that the magnetic fluid dynamics effect exists in the MF-corrosion coupling environment. The Lorentz force promotes the accelerated flow of the electrolyte solution, which produces the convection phenomenon. The corrosion rate changes nonlinearly with the MF strength: low MF strength promotes the corrosion process of Q355B steel, while medium MF strength and high MF strength inhibit corrosion. Moreover, the vertical MF leads to the uneven distribution of the potential on the surface of the steel, which is more likely to cause uneven corrosion than the parallel MF. The research results provide an important reference for the corrosion failure mechanism of Q355B steel in complex MF-corrosion coupling environment.