Abstract
The effect of additional elements in low-alloy steel on the protective rust layer has been discussed from the view point of atmospheric corrosion.
The rust layer of corrosion resistant low-alloy steel is made up of two layers, the outer one which is α or γ FeOOH and the inner one which is amorphous or very fine spinel type oxide (Fe3O4).
The inner layer is supposed to play an important role in the corrosion resistance of low-alloy steels in atmosphere.
The method of detecting the above-mentioned dense amorphous oxide layer is presented, and the mechanism of its formation is also discussed.
