High temperature oxidation of duplex stainless steels

Abstract

Hot rolling and solution annealing of duplex stainless steels involve high temperature reheating steps in oxidizing atmospheres. The thin scale that forms on the surface is not easily removed because it contains oxide nodules that are deeply embedded in the underlying alloy. These nodules appear when the protective Cr₂O₃ layer becomes locally inefficient. At the same place, oxidation of iron and manganese is possible and less chromium is needed to develop the scale. Depletion of chromium in the steel beneath the nodule is then less important and pickling the plates becomes more difficult.