A proposal to evaluate the amount of corroded iron converted into adherent rust in steels exposed to corrosion

To calculate the amount of iron corroded from the steels that form part of the adherent rust, α, we propose a procedure that considers mass measurements and the use of spectroscopic techniques to estimate the relative iron phase abundances. We derived an equation to calculate α and evaluate it for carbon steels (CS) and weathering steels (WS) exposed to accelerated outdoor corrosion tests. The values of α are estimated at 0.93 and 0.76 for CS and WS after 2 years of exposure, respectively. The relative iron phase abundances pointed out to a non-protective and active type of rust.

Research highlights
► A formula for α, the amount of dissolved iron forming the adherent rust, was derived.
► After 2 years of exposure α was 0.93 and 0.76 for CS and WS, respectively.
► The relative iron phase abundances show a non-protective and active type of rusts.