Effect of trace boron on corrosion resistance of rust layer of high-strength low-alloy steel in 3.5 wt.% NaCl solution

The influence mechanism of trace boron on the corrosion resistance of high-strength low-alloy (HSLA) steel in a simulated marine environment was studied by combining first-principles calculation with experiment. The effect of boron on the corrosion properties and corrosion morphology of the rust layer formed on the surface of HSLA steel was studied by means of corrosion weightlessness method, polarization curve, scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique. The mass loss measurements and polarization curves revealed that the corrosion resistance of HSLA steel is improved by adding trace boron. XRD and SEM results show that the rust layer is produced by α-FeOOH (the main protective phase), Fe3O4 and γ-FeOOH, and boron contributes to stability of α-FeOOH. Based on the first-principles calculation, the solid solution of B atom in the corrosion product is beneficial to the fixation of Cl atom and to the reduction of the corrosion of Cl atom to the steel matrix.