Lateral variation of the native passive film on super duplex stainless steel resolved by synchrotron hard X-ray photoelectron emission microscopy.

• Microscopic chemical analysis of anative passive film on 25Cr-7Ni super duplex stainless steel was analyzed by synchrotron HAXPEEM. • Results reveal lateral variations in thickness and Cr content of the passive film between individual grains of ferrite and austenite phases. • The Cr content is higher on ferrite than austenite, whereas the thickness is rather uniform. • Grain orientation has a small but detectable influence, ferrite (111) grains have a lower Cr content than other ferrite grains. A native passive film on 25Cr-7Ni super duplex stainless steel was analyzed using synchrotron hard X-ray photoemission electron microscopy, focusing on variations between individual grains of ferrite and austenite phases. The film consists of an oxide inner layer and an oxyhydroxide outer layer, in total 2.3 nm thick. The Cr content is higher in the outer than the inner layer, ca. 80 % on average. The Cr content is higher on ferrite than austenite, whereas the thickness is rather uniform. The grain orientation has a small but detectable influence, ferrite (111) grains have a lower Cr content than other ferrite grains. [ABSTRACT FROM AUTHOR]