Corrosion resistance of Si- and Al-rich steels in flowing lead–bismuth

Corrosion resistance of Si- and Al-rich steels in lead–bismuth flow was studied experimentally. The specimens of SUH3 (10Cr–1Mo–2Si), NTK04L (18Cr–3Al) and Recloy10 (18Cr–1Al–1Si) were exposed to flowing lead–bismuth for 500–2000 h. After the exposure, metallurgical analysis of their surfaces and weight loss measurement of the specimens were carried out. The surface of the Si-rich steels, SUH3, was smooth with no liquid metal corrosion. Double-oxide layers were observed on the surface of SUH3 steel, where an inner layer might serve as a barrier for the liquid metal corrosion attack, while the outer layer could detach from the surface. An initial metallic luster of the surfaces remained on NTK04L and Recloy 10 steels after the exposure. An Al-rich single layer was formed and stuck on the steel surfaces. This layer protected the steel matrix from the corrosion. The weight losses of these Al-rich steels, NTK04L and Recloy10, in the exposure for the time up to 2000 h were negligibly small.